---
id:
aliases:
  - nec-430
tags:
  - authorship/other
  - destiny/uncertain
  - exclude-from-word-count
  - status/draft
  - topic/construction/electrical
  - type/media/reference
title: Article 430 Motors, Motor Circuits, and Controllers
---
# Article 430 Motors, Motor Circuits, and Controllers

## Part I. General

### 430.1 Scope.

This article covers motors,
motor branch-circuit and feeder conductors and their protection,
motor overload protection, motor control circuits,
motor controllers, and motor control centers.

### 430.2 Definitions.

The definitions in this section shall apply only within this article.

#### Controller.

Any switch or device that is normally used to start and stop a motor by making and breaking the motor circuit current.

#### Electronically Protected (as applied to motors).

A motor that is provided with electronic control that is an integral part of the motor and protects the motor against dangerous overheating due to failure of the electronic control, overload and failure to start.

#### Part-Winding Motors.

A part-winding start induction or synchronous motor is one that is arranged for starting by first energizing part of its primary (armature) winding and, subsequently, energizing the remainder of this winding in one or more steps. A standard part-winding start induction motor is arranged so that one-half of its primary winding can be energized initially, and, subsequently, the remaining half can be energized, both halves then carrying equal current.

> [!info] Informational Note:
> A hermetic refrigerant motor-compressor is not considered a standard part-winding start induction motor.

#### System Isolation Equipment.

A redundantly monitored, remotely operated contactor-isolating system, packaged to provide the disconnection/isolation function, capable of verifiable operation from multiple remote locations by means of lockout switches, each having the capability of being padlocked in the “off” (open) position.

#### Valve Actuator Motor (VAM) Assemblies.

A manufactured assembly, used to operate a valve, consisting of an actuator motor and other components such as controllers, torque switches, limit switches, and overload protection.

> [!info] Informational Note:
> VAMs typically have short-time duty and high-torque characteristics.

### 430.4 Part-Winding Motors.

Where separate overload devices are used with a standard part-winding start induction motor, each half of the motor winding shall be individually protected in accordance with 430.32 and 430.37 with a trip current one-half that specified.

Each motor-winding connection shall have branch-circuit short-circuit and ground-fault protection rated at not more than one-half that specified by 430.52.

> [!important] Exception:
> A short-circuit and ground-fault protective device shall be permitted for both windings if the device will allow the motor to start. Where time-delay (dual-element) fuses are used, they shall be permitted to have a rating not exceeding 150 percent of the motor full-load current.

### 430.5 Other Articles.

Motors and controllers shall also comply with the applicable provisions of Table 430.5.

#### Table 430.5 Other Articles

| Equipment/Occupancy                                                                                                                                                                    | Article                                  | Section           |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------- | ----------------- |
| Air-conditioning and refrigerating equipment                                                                                                                                           | 440                                      |                   |
| Capacitors 460.8,                                                                                                                                                                      |                                          | 460.9             |
| Commercial garages; aircraft hangars; motor fuel dispensing facilities; bulk storage plants; spray application, dipping, and coating processes; and inhalation anesthetizing locations | 511, 513, 514, 515, 516, and 517 Part IV |                   |
| Cranes and hoists                                                                                                                                                                      | 610                                      |                   |
| Electrically driven or controlled irrigation machines                                                                                                                                  | 675                                      |                   |
| Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts                                                                                           | 620                                      |                   |
| Fire pumps                                                                                                                                                                             | 695                                      |                   |
| Hazardous (classified) locations                                                                                                                                                       | 500–503, 505, and 506                    |                   |
| Industrial machinery                                                                                                                                                                   | 670                                      |                   |
| Motion picture projectors                                                                                                                                                              |                                          | 540.11 and 540.20 |
| Motion picture and television studios and similar locations                                                                                                                            | 530                                      |                   |
| Resistors and reactors                                                                                                                                                                 | 470                                      |                   |
| Theaters, audience areas of motion picture and television studios, and similar locations                                                                                               |                                          | 520.48            |
| Transformers and transformer vaults                                                                                                                                                    | 450                                      |                   |

### 430.6 Ampacity and Motor Rating Determination.

The size of conductors supplying equipment covered by Article 430 shall be selected from the ampacity tables in accordance with 310.15 or shall be calculated in accordance with 310.14(B). Where flexible cord is used, the size of the conductor shall be selected in accordance with 400.5. The required ampacity and motor ratings shall be determined as specified in 430.6(A), (B), (C), and (D).

#### 430.6(A) General Motor Applications.

For general motor applications, current ratings shall be determined based on 430.6(A) (1) and (A)(2).

##### 430.6(A)(1) Table Values.

Other than for motors built for low speeds (less than 1200 RPM) or high torques, and for multispeed motors, the values given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 shall be used to determine the ampacity of conductors or ampere ratings of switches, branch-circuit short-circuit and ground-fault protection, instead of the actual current rating marked on the motor nameplate.

Where a motor is marked in amperes, but not horsepower, the horsepower rating shall be assumed to be that corresponding to the value given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250, interpolated if necessary. Motors built for low speeds
(less than 1200 RPM) or high torques may have higher full-load currents, and multispeed motors will have full-load current varying with speed, in which case the nameplate current ratings shall be used.

> [!important] Exception No. 1:
> Multispeed motors shall be in accordance with 430.22(B) and 430.52.

> [!important] Exception No. 2:
> For equipment that employs a shaded-pole or permanent-split capacitor-type fan or blower motor that is marked with the motor type, the full load current for such motor marked on the nameplate of the equipment in which the fan or blower motor is employed shall be used instead of the horsepower rating to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and the separate overload protection. This marking on the equipment nameplate shall not be less than the current marked on the fan or blower motor nameplate.

> [!important] Exception No. 3:
> For a listed motor-operated appliance that is marked with both motor horsepower and full-load current, the motor fullload current marked on the nameplate of the appliance shall be used instead of the horsepower rating on the appliance nameplate to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and any separate overload protection.

##### 430.6(A)(2) Nameplate Values.

Separate motor overload protection shall be based on the motor nameplate current rating.

#### 430.6(B) Torque Motors.

For torque motors, the rated current shall be locked-rotor current, and this nameplate current shall be used to determine the ampacity of the branch-circuit conductors covered in 430.22 and 430.24, the ampere rating of the motor overload protection, and the ampere rating of motor branch-circuit short-circuit and ground-fault protection in accordance with 430.52(B).

> [!info] Informational Note:
> For motor controllers and disconnecting means, see 430.83(D) and 430.110.

#### 430.6(C) Alternating-Current Adjustable Voltage Motors.

For motors used in alternating-current, adjustable voltage, variable torque drive systems, the ampacity of conductors, or ampere ratings of switches, branch-circuit short-circuit and ground-fault protection, and so forth, shall be based on the maximum operating current marked on the motor or control nameplate, or both. If the maximum operating current does not appear on the nameplate, the ampacity determination shall be based on 150 percent of the values given in Table 430.249 and Table 430.250.

#### 430.6(D) Valve Actuator Motor Assemblies.

For valve actuator motor assemblies (VAMs), the rated current shall be the nameplate full-load current, and this current shall be used to determine the maximum rating or setting of the motor branch-circuit short-circuit and ground-fault protective device and the ampacity of the conductors.

### 430.7 Marking on Motors and Multimotor Equipment.

#### 430.7(A) Usual Motor Applications.

A motor shall be marked with the following information:

* (1) Manufacturer’s name.

* (2) Rated volts and full-load current. For a multispeed motor, full-load current for each speed, except shaded-pole and permanentsplit capacitor motors where amperes are required only for maximum speed.

* (3) Rated frequency and number of phases if an ac motor.

* (4) Rated full-load speed.

* (5) Rated temperature rise or the insulation system class and rated ambient temperature.

* (6) Time rating. The time rating shall be 5, 15, 30, or 60 minutes, or continuous.

* (7) Rated horsepower if 1⁄8 hp or more. For a multispeed motor 1⁄8 hp or more, rated horsepower for each speed, except shadedpole and permanent-split capacitor motors 1⁄8 hp or more where rated horsepower is required only for maximum speed. Motors of arc welders are not required to be marked with the horsepower rating.

* (8) Code letter or locked-rotor amperes if an alternating-current motor rated 1⁄2 hp or more. On polyphase wound-rotor motors, the code letter shall be omitted.

> [!info] Informational Note:
> See 430.7(B).

* (9) Design letter for design B, C, or D motors.

> [!info] Informational Note:
> Motor design letter definitions are found in ANSI/NEMA MG 1-1993, Motors and Generators, Part 1,

Definitions, and in IEEE 100-1996, Standard Dictionary of Electrical and Electronic Terms.

* (10) Secondary volts and full-load current if a wound-rotor induction motor.

* (11) Field current and voltage for dc excited synchronous motors.

* (12) Winding — straight shunt, stabilized shunt, compound, or series, if a dc motor. Fractional horsepower dc motors 175 mm (7 in.) or less in diameter shall not be required to be marked.

* (13) A motor provided with a thermal protector complying with 430.32(A)(2) or (B)(2) shall be marked “thermally protected.”

Thermally protected motors rated 100 watts or less and complying with 430.32(B)(2) shall be permitted to use the abbreviated marking “T.P.”

* (14) A motor complying with 430.32(B)(4) shall be marked “impedance protected.” Impedance-protected motors rated 100 watts or less and complying with 430.32(B)(4) shall be permitted to use the abbreviated marking “Z.P.”

* (15) Motors equipped with electrically powered condensation prevention heaters shall be marked with the rated heater voltage, number of phases, and the rated power in watts.

* (16) Motors that are electronically protected from overloads in accordance with 430.32(A)(2) and (B)(2) shall be marked “electronically protected” or “E.P.”

#### 430.7(B) Locked-Rotor Indicating Code Letters.

Code letters marked on motor nameplates to show motor input with locked rotor shall be in accordance with Table 430.7(B).

The code letter indicating motor input with locked rotor shall be in an individual block on the nameplate, properly designated.

##### Table 430.7(B) Locked-Rotor Indicating Code Letters

| Code Letter | Kilovolt-Amperes per Horsepower with Locked Rotor |
| ----------- | ------------------------------------------------- |
| A           | 0–3.14                                            |
| B           | 3.15–3.54                                         |
| C           | 3.55–3.99                                         |
| D           | 4.0–4.49                                          |
| E           | 4.5–4.99                                          |
| F           | 5.0–5.59                                          |
| G           | 5.6–6.29                                          |
| H           | 6.3–7.09                                          |
| J           | 7.1–7.99                                          |
| K           | 8.0–8.99                                          |
| L           | 9.0–9.99                                          |
| M           | 10.0–11.19                                        |
| N           | 11.2–12.49                                        |
| P           | 12.5–13.99                                        |
| R           | 14.0–15.99                                        |
| S           | 16.0–17.99                                        |
| T           | 18.0–19.99                                        |
| U           | 20.0–22.39                                        |
| V           | 22.4 and up                                       |

##### 430.7(B)(1) Multispeed Motors.

Multispeed motors shall be marked with the code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) for the highest speed at which the motor can be started.

> [!important] Exception:
> Constant horsepower multispeed motors shall be marked with the code letter giving the highest locked-rotor kilovolt-ampere (kVA) per horsepower (hp).

##### 430.7(B)(2) Single-Speed Motors.

Single-speed motors starting on wye connection and running on delta connections shall be marked with a code letter corresponding to the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) for the wye connection.

##### 430.7(B)(3) Dual-Voltage Motors.

Dual-voltage motors that have a different locked-rotor kilovolt-ampere (kVA) per horsepower (hp) on the two voltages shall be marked with the code letter for the voltage giving the highest locked-rotor kilovolt-ampere (kVA) per horsepower (hp).

##### 430.7(B)(4) 50/60 Hz Motors.

Motors with 50- and 60-Hz ratings shall be marked with a code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) on 60 Hz.

##### 430.7(B)(5) Part-Winding Motors.

Part-winding start motors shall be marked with a code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) that is based on the locked-rotor current for the full winding of the motor.

#### 430.7(C) Torque Motors.

Torque motors are rated for operation at standstill and shall be marked in accordance with 430.7(A), except that locked-rotor torque shall replace horsepower.

#### 430.7(D) Multimotor and Combination-Load Equipment.

##### 430.7(D)(1) Factory-Wired.

Multimotor and combination-load equipment shall be provided with a visible nameplate marked with the manufacturer’s name, the rating in volts, frequency, number of phases, minimum supply circuit conductor ampacity, and the maximum ampere rating of the circuit short-circuit and ground-fault protective device. The conductor ampacity shall be calculated in accordance with 430.24 and counting all of the motors and other loads that will be operated at the same time. The short-circuit and ground-fault protective device rating shall not exceed the value calculated in accordance with 430.53. Multimotor equipment for use on two or more circuits shall be marked with the preceding information for each circuit.

##### 430.7(D)(2) Not Factory-Wired.

Where the equipment is not factory-wired and the individual nameplates of motors and other loads are visible after assembly of the equipment, the individual nameplates shall be permitted to serve as the required marking.

### 430.8 Marking on Controllers.

A controller shall be marked with the manufacturer’s name or identification, the voltage, the current or horsepower rating, the short-circuit current rating, and other necessary data to properly indicate the applications for which it is suitable.

> [!important] Exception No. 1:
> The short-circuit current rating is not required for controllers applied in accordance with 430.81(A) or (B).

> [!important] Exception No. 2:
> The short-circuit rating is not required to be marked on the controller when the short-circuit current rating of the controller is marked elsewhere on the assembly.

> [!important] Exception No. 3:
> The short-circuit rating is not required to be marked on the controller when the assembly into which it is installed has a marked short-circuit current rating.

> [!important] Exception No. 4:
> Short-circuit ratings are not required for controllers rated less than 2 hp at 300 V or less and listed exclusively for general-purpose branch circuits.

A controller that includes motor overload protection suitable for group motor application shall be marked with the motor overload protection and the maximum branch-circuit short-circuit and ground-fault protection for such applications.

Combination controllers that employ adjustable instantaneous trip circuit breakers shall be clearly marked to indicate the ampere settings of the adjustable trip element.

Where a controller is built in as an integral part of a motor or of a motor-generator set, individual marking of the controller shall not be required if the necessary data are on the nameplate. For controllers that are an integral part of equipment approved as a unit, the above marking shall be permitted on the equipment nameplate.

> [!info] Informational Note:
> See 110.10 for information on circuit impedance and other characteristics.

### 430.9 Terminals.

#### 430.9(A) Markings.

Terminals of motors and controllers shall be suitably marked or colored where necessary to indicate the proper connections.

#### 430.9(B) Conductors.

Motor controllers and terminals of control circuit devices shall be connected with copper conductors unless identified for use with a different conductor.

#### 430.9(C) Torque Requirements.

Control circuit devices with screw-type pressure terminals used with 14 AWG or smaller copper conductors shall be torqued to a minimum of 0.8 N·m (7 lb- in.) unless identified for a different torque value.

### 430.10 Wiring Space in Enclosures.

#### 430.10(A) General.

Enclosures for motor controllers and disconnecting means shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to the other apparatus unless designs are employed that provide adequate space for this purpose.

> [!info] Informational Note:
> See 312.8 for switch and overcurrent-device enclosures.

#### 430.10(B) Wire-Bending Space in Enclosures.

Minimum wire-bending space within the enclosures for motor controllers shall be in accordance with Table 430.10(B) where measured in a straight line from the end of the lug or wire connector (in the direction the wire leaves the terminal) to the wall or barrier. Where alternate wire termination means are substituted for that supplied by the manufacturer of the controller, they shall be of a type identified by the manufacturer for use with the controller and shall not reduce the minimum wire-bending space.

##### Table 430.10(B) Minimum Wire-Bending Space at the Terminals of Enclosed Motor Controllers

Size of Wire (AWG or kcmil) Wires per Terminal
1 2
* mm in. mm in.

Size of Wire (AWG or kcmil) Wires per Terminal
1 2 mm in. mm in.
10 and smaller Not specified — —
8–6 38 11⁄2 — —
4–3 50 2 — —
2 65 21⁄2 — —
1 75 3 — —
1/0 125 5 125 5
2/0 150 6 150 6
3/0–4/0 175 7 175 7
250 200 8 200 8
300 250 10 250 10
350–500 300 12 300 12
600–700 350 14 400 16
750–900 450 18 475 19

Where provision for three or more wires per terminal exists, the minimum wire-bending space shall be in accordance with the requirements of Article 312.

### 430.11 Protection Against Liquids.

Suitable guards or enclosures shall be provided to protect exposed current-carrying parts of motors and the insulation of motor leads where instal led directly under equipment, or in other locations where dripping or spraying oil, water, or other liquid is capable of occurring, unless the motor is designed for the existing conditions.

### 430.12 Motor Terminal Housings.

#### 430.12(A) Material.

Where motors are provided with terminal housings, the housings shall be of metal and of substantial construction.

> [!important] Exception:
> In other than hazardous (classified) locations, substantial, nonmetallic, noncombustible housings shall be permitted, provided an internal grounding means between the motor frame and the equipment grounding connection is incorporated within the housing.

#### 430.12(B) Dimensions and Space — Wire-to-Wire Connections.

Where these terminal housings enclose wire-to-wire connections, they shall have minimum dimensions and usable volumes in accordance with Table 430.12(B).

##### Table 430.12(B) Terminal Housings — Wire-to-Wire Connections

Motors 275 mm (11 in.) in Diameter or Less

| Horsepower                  | Cover Opening Minimum Dimension | Usable Volume Minimum                     |
| --------------------------- | ------------------------------- | ----------------------------------------- |
| 1 and smaller<sup>a</sup>   | 41 mm (1 5⁄8 in.)               | 170 cm<sup>3</sup> (10.5 in.<sup>3</sup>) |
| 1 1⁄2, 2, and 3<sup>b</sup> | 45 mm (1 3⁄4 in.)               | 275 cm<sup>3</sup> (16.8 in.<sup>3</sup>) |
| 5 and 7 1⁄2                 | 50 mm (2 in.)                   | 365 cm<sup>3</sup> (22.4 in.<sup>3</sup>) |
| 10 and 15                   | 65 mm (2 1⁄2 in.)               | 595 cm<sup>3</sup> (36.4 in.<sup>3</sup>) |

Motors Over 275 mm (11 in.) in Diameter — Alternating-Current Motors

| Maximum Full Load Current for 3-Phase Motors with Maximum of 12 Leads (Amperes) | Terminal Box Cover Opening Minimum Dimension | Usable Volume Minimum                       | Typical Maximum Horsepower 3-Phase, 230 Volt | Typical Maximum Horsepower 3-Phase, 460 Volt |
| ------------------------------------------------------------------------------- | -------------------------------------------- |:------------------------------------------- |:-------------------------------------------- | -------------------------------------------- |
| 45                                                                              | 65 mm (2.5 in.)                              | 595 cm<sup>3</sup> (36.4 in.<sup>3</sup>)   | 15                                           | 30                                           |
| 70                                                                              | 84 mm (3.3 in.)                              | 1265 cm<sup>3</sup> (77 in.<sup>3</sup>)    | 25                                           | 50                                           |
| 110                                                                             | 100 mm (4.0 in.)                             | 2295 cm<sup>3</sup> (140 in.<sup>3</sup>)   | 40                                           | 75                                           |
| 160                                                                             | 125 mm (5.0 in.)                             | 4135 cm<sup>3</sup> (252 in.<sup>3</sup>)   | 60                                           | 125                                          |
| 250                                                                             | 150 mm (6.0 in.)                             | 7380 cm<sup>3</sup> (450 in.<sup>3</sup>)   | 100                                          | 200                                          |
| 400                                                                             | 175 mm (7.0 in.)                             | 13775 cm<sup>3</sup> (840 in.<sup>3</sup>)  | 150                                          | 300                                          |
| 600                                                                             | 200 mm (8.0 in.)                             | 25255 cm<sup>3</sup> (1540 in.<sup>3</sup>) | 250                                          | 500                                          |

Direct-Current Motors

| Maximum Full-Load Current for Motors with Maximum of 6 Leads (Amperes) | Terminal Box Minimum Dimensions |                       Usable Volume Minimum |
| ---------------------------------------------------------------------- | ------------------------------- | -------------------------------------------:|
| 68                                                                     | 65 mm (2.5 in.)                 |     425 cm<sup>3</sup> (26 in.<sup>3</sup>) |
| 105                                                                    | 84 mm (3.3 in.)                 |     900 cm<sup>3</sup> (55 in.<sup>3</sup>) |
| 165                                                                    | 100 mm (4.0 in.)                |   1640 cm<sup>3</sup> (100 in.<sup>3</sup>) |
| 240                                                                    | 125 mm (5.0 in.)                |   2950 cm<sup>3</sup> (180 in.<sup>3</sup>) |
| 375                                                                    | 150 mm (6.0 in.)                |   5410 cm<sup>3</sup> (330 in.<sup>3</sup>) |
| 600                                                                    | 175 mm (7.0 in.)                |   9840 cm<sup>3</sup> (600 in.<sup>3</sup>) |
| 900                                                                    | 200 mm (8.0 in.)                | 18040 cm<sup>3</sup> (1100 in.<sup>3</sup>) |

Note: Auxiliary leads for such items as brakes, thermostats, space heaters, and exciting fields shall be permitted to be neglected if their current-carrying area does not exceed 25 percent of the current-carrying area of the machine power leads.

<sup>a</sup>For motors rated 1 hp and smaller, and with the terminal housing partially or wholly integral with the frame or end shield, the volume of the terminal housing shall not be less than 18.0 cm (1.1 in. ) per wire-to-wire connection. The minimum cover opening dimension is not specified.

<sup>b</sup>For motors rated 1 1⁄2, 2, and 3 hp, and with the terminal housing partially or wholly integral with the frame or end shield, the volume of the terminal housing shall not be less than 23.0 cm (1.4 in. ) per wire-to-wire connection. The minimum cover opening dimension is not specified.

#### 430.12(C) Dimensions and Space — Fixed Terminal Connections.

Where these terminal housings enclose rigidly mounted motor terminals, the terminal housing shall be of sufficient size to provide minimum terminal spacings and usable volumes in accordance with Table 430.12(C)(1) and Table 430.12(C)(2).

##### Table 430.12(C)(1) Terminal Spacings — Fixed Terminals

| Nominal Volts   | Minimum Spacing Between Line Terminals | Minimum Spacing Between Line Terminals and Other Uninsulated Metal Parts |
| --------------- | -------------------------------------- | ------------------------------------------------------------------------ |
| 250 or less     | 6 mm (1⁄4 in.)                         | 6 mm (1⁄4 in.)                                                           |
| Over 250 – 1000 | 10 mm (3⁄8 in.)                        | 10 mm (3⁄8 in.)                                                          |

#### Table 430.12(C)(2) Usable Volumes — Fixed Terminals

| Power-Supply Conductor Size (AWG) | Minimum Usable Volume per Power-Supply Conductor |
| --------------------------------- | ------------------------------------------------ |
| 14                                | 16 cm<sup>3</sup> (1 in.<sup>3</sup>             |
| 12 and 10                         | 20 cm<sup>3</sup> (1 1⁄4 in.<sup>3</sup>         |
| 8 and 6                           | 37 cm<sup>3</sup> (2 1⁄4 in.<sup>3</sup>         |

#### 430.12(D) Large Wire or Factory Connections.

For motors with larger ratings, greater number of leads, or larger wire sizes, or where motors are installed as a part of factory-wired equipment, without additional connection being required at the motor terminal housing during equipment installation, the terminal housing shall be of ample size to make connections, but the foregoing provisions for the volumes of terminal housings shall not be considered applicable.

#### 430.12(E) Equipment Grounding Connections.

A means for attachment of an equipment grounding conductor termination in accordance with 250.8 shall be provided at motor terminal housings for wire-to-wire connections or fixed terminal connections. The means for such connections shall be permitted to be located either inside or outside the motor terminal housing.

> [!important] Exception:
> Where a motor is installed as a part of factory-wired equipment that is required to be grounded and without additional connection being required at the motor terminal housing during equipment installation, a separate means for motor grounding at the motor terminal housing shall not be required.

### 430.13 Bushing.

Where wires pass through an opening in an enclosure, conduit box, or barrier, a bushing shall be used to protect the conductors from the edges of openings having sharp edges. The bushing shall have smooth, well-rounded surfaces where it may be in contact with the conductors. If used where oils, greases, or other contaminants may be present, the bushing shall be made of material not deleteriously affected.

> [!info] Informational Note:
> For conductors exposed to deteriorating agents, see 310.10(F).

### 430.14 Location of Motors.

#### 430.14(A) Ventilation and Maintenance.

Motors shall be located so that adequate ventilation is provided and so that maintenance, such as lubrication of bearings and replacing of brushes, can be readily accomplished.

> [!important] Exception:
> Ventilation shall not be required for submersible types of motors.

#### 430.14(B) Open Motors.

Open motors that have commutators or collector rings shall be located or protected so that sparks cannot reach adjacent combustible material.

> [!important] Exception:
> Installation of these motors on wooden floors or supports shall be permitted.

### 430.16 Exposure to Dust Accumulations.

In locations where dust or flying material collects on or in motors in such quantities as to seriously interfere with the ventilation or cooling of motors and thereby cause dangerous temperatures, suitable types of enclosed motors that do not overheat under the prevailing conditions shall be used.

> [!info] Informational Note:
> Especially severe conditions may require the use of enclosed pipe-ventilated motors, or enclosure in separate dusttight rooms, properly ventilated from a source of clean air.

### 430.17 Highest Rated or Smallest Rated Motor.

In determining compliance with 430.24, 430.53(B), and 430.53(C), the highest rated or smallest rated motor shall be based on the rated full-load current as selected from Table 430.247, Table 430.248, Table 430.249, and Table 430.250.

### 430.18 Nominal Voltage of Rectifier Systems.

The nominal value of the ac voltage being rectified
shall be used to determine the voltage of a rectifier derived system.

> [!important] Exception:
> The nominal dc voltage of the rectifier shall be used
> if it exceeds the peak value of the ac voltage being rectified.

## Part II. Motor Circuit Conductors

### 430.21 General.

Part II specifies ampacities of conductors
that are capable of carrying the motor current
without overheating under the conditions specified.

Part II shall not apply to motor circuits rated over 1000 volts, nominal.

Informational Note:
For over 1000 volts, nominal, see Part XI.

Articles 250, 300, and 310 shall not apply
to conductors that form an integral part of equipment,
such as motors, motor controllers, motor control centers,
or other factory-assembled control equipment.

Informational Note:
See 110.14(C) and 430.9(B) for equipment device terminal requirements.

### 430.22 Single Motor.

Conductors that supply a single motor
used in a continuous duty application
shall have an ampacity of not less than 125 percent
of the motor full-load current rating,
as determined by 430.6(A)(1),
or not less than specified in 430.22(A) through (G).

#### 430.22(A) Direct-Current Motor-Rectifier Supplied.

For dc motors operating from a rectified power supply, the conductor ampacity on the input of the rectifier shall not be less than
125 percent of the rated input current to the rectifier. For dc motors operating from a rectified single-phase power supply, the conductors between the field wiring output terminals of the rectifier and the motor shall have an ampacity of not less than the following percentages of the motor full-load current rating:

* (1) Where a rectifier bridge of the single-phase, half-wave type is used, 190 percent.

* (2) Where a rectifier bridge of the single-phase, full-wave type is used, 150 percent.

#### 430.22(B) Multispeed Motor.

For a multispeed motor, the selection of branch-circuit conductors on the line side of the controller shall be based on the highest of the full-load current ratings shown on the motor nameplate. The ampacity of the branch-circuit conductors between the controller and the motor shall not be less than 125 percent of the current rating of the winding(s) that the conductors energize.

#### 430.22(C) Wye-Start, Delta-Run Motor.

For a wye-start, delta-run connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125 percent of the motor full-load current as determined by 430.6(A)(1). The ampacity of the conductors between the controller and the motor shall not be less than 72 percent of the motor full-load current rating as determined by 430.6(A) (1).

> [!info] Informational Note:
> The individual motor circuit conductors of a wye-start, delta-run connected motor carry 58 percent of the rated load current. The multiplier of 72 percent is obtained by multiplying 58 percent by 1.25.

#### 430.22(D) Part-Winding Motor.

For a part-winding connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125 percent of the motor full-load current as determined by 430.6(A)(1). The ampacity of the conductors between the controller and the motor shall not be less than 62.5 percent of the motor full-load current rating as determined by 430.6(A)(1).

> [!info] Informational Note:
> The multiplier of 62.5 percent is obtained by multiplying 50 percent by 1.25.

#### 430.22(E) Other Than Continuous Duty.

Conductors for a motor used in a short-time, intermittent, periodic, or varying duty application shall have an ampacity of not less than the percentage of the motor nameplate current rating shown in Table 430.22(E), unless the authority having jurisdiction grants special permission for conductors of lower ampacity.

##### Table 430.22(E) Duty-Cycle Service

Classification of Service

Nameplate Current Rating

Percentages
5Minute

Rated

Motor
15MinuteRated

Motor
30- &
60-

Minute

Rated

Motor

Continuous

Rated

Motor

| Short-time duty operating valves, raising or lowering rolls, etc. | 110 | 120 | 150 | — |
| Intermittent duty freight and passenger elevators, tool heads, pumps, drawbridges, turntables, etc. (for arc welders, see 630.11) | 85 | 85 | 90 | 140 |
| Periodic duty rolls, ore- and coal-handling machines, etc. | 85 | 90 | 95 | 140 |
| Varying duty | 110 | 120 | 150 | 200 |

Note: Any motor application shall be considered as continuous duty unless the nature of the apparatus it drives is such that the motor will not operate continuously with load under any condition of use.

#### 430.22(F) Separate Terminal Enclosure.

The conductors between a stationary motor rated 1 hp or less and the separate terminal enclosure permitted in 430.245(B) shall be permitted to be smaller than 14 AWG but not smaller than 18 AWG, provided they have an ampacity as specified in 430.22.

#### 430.22(G) Conductors for Small Motors.

Conductors for small motors shall not be smaller than 14 AWG unless otherwise permitted in 430.22(G)(1) or (G)(2).

##### 430.22(G)(1) 18 AWG Copper.

18 AWG individual copper conductors installed in a cabinet or enclosure, copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted, under either of the following sets of conditions:

* (1) The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of greater than 3.5 amperes, and less than or equal to 5 amperes, and all the following conditions are met:
    * a. The circuit is protected in accordance with 430.52.
    * b. The circuit is provided with maximum Class 10 or Class 10A overload protection in accordance with 430.32.
    * c. Overcurrent protection is provided in accordance with 240.4(D)(1)(2).

* (2) The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of 3.5 amperes or less, and all the following conditions are met:
    * a. The circuit is protected in accordance with 430.52.
    * b. The circuit is provided with maximum Class 20 overload protection in accordance with 430.32.
    * c. Overcurrent protection is provided in accordance with 240.4(D)(1)(2).

##### 430.22(G)(2) 16 AWG Copper.

16 AWG individual copper conductors installed in a cabinet or enclosure, copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted under either of the following sets of conditions:

* (1) The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of greater than 5.5 amperes, and less than or equal to 8 amperes, and all the following conditions are met:
    * a. The circuit is protected in accordance with 430.52.
    * b. The circuit is provided with maximum Class 10 or Class 10A overload protection in accordance with 430.32.
    * c. Overcurrent protection is provided in accordance with 240.4(D)(2)(2).

* (2) The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of 5.5 amperes or less, and all the following conditions are met:
    * a. The circuit is protected in accordance with 430.52.
    * b. The circuit is provided with maximum Class 20 overload protection in accordance with 430.32.
    * c. Overcurrent protection is provided in accordance with 240.4(D)(2)(2).

### 430.23 Wound-Rotor Secondary.

#### 430.23(A) Continuous Duty.

For continuous duty, the conductors connecting the secondary of a wound-rotor ac motor to its controller shall have an ampacity not less than 125 percent of the full-load secondary current of the motor.

#### 430.23(B) Other Than Continuous Duty.

For other than continuous duty, these conductors shall have an ampacity, in percent of full-load secondary current, not less than that specified in Table 430.22(E).

#### 430.23(C) Resistor Separate from Controller.

Where the secondary resistor is separate from the controller, the ampacity of the conductors between controller and resistor shall not be less than that shown in Table 430.23(C).

##### Table 430.23(C) Secondary Conductor

| Resistor Duty Classification | Ampacity of Conductor in Percent of Full-Load Secondary Current |
|:---------------------------- | ---------------------------------------------------------------:|
| Light starting duty          |                                                              35 |
| Heavy starting duty          |                                                              45 |
| Extra-heavy starting duty    |                                                              55 |
| Light intermittent duty      |                                                              65 |
| Medium intermittent duty     |                                                              75 |
| Heavy intermittent duty      |                                                              85 |
| Continuous duty              |                                                             110 |

### 430.24 Several Motors or a Motor(s) and Other Load(s).

Conductors supplying several motors, or a motor(s) and other load(s), shall have an ampacity not less than the sum of each of the following:

* (1) 125 percent of the full-load current rating of the highest rated motor, as determined by 430.6(A)

* (2) Sum of the full-load current ratings of all the other motors in the group, as determined by 430.6(A)

* (3) 100 percent of the noncontinuous non-motor load

* (4) 125 percent of the continuous non-motor load.

> [!info] Informational Note:
> See Informative Annex D, Example No. D8.

> [!important] Exception No. 1:
> Where one or more of the motors of the group are used for short-time, intermittent, periodic, or varying duty, the ampere rating of such motors to be used in the summation shall be determined in accordance with 430.22(E). For the highest rated motor, the greater of either the ampere rating from 430.22(E) or the largest continuous duty motor full-load current multiplied by 1.25 shall be used in the summation.

> [!important] Exception No. 2:
> The ampacity of conductors supplying motor-operated fixed electric space-heating equipment shall comply with 424.4(B).

> [!important] Exception No. 3:
> Where the circuitry is interlocked so as to prevent simultaneous operation of selected motors or other loads, the conductor ampacity shall be permitted to be based on the summation of the currents of the motors and other loads to be operated simultaneously that results in the highest total current.

### 430.25 Multimotor and Combination-Load Equipment.

The ampacity of the conductors supplying multimotor and combination-load equipment shall not be less than the minimum circuit ampacity marked on the equipment in accordance with 430.7(D). Where the equipment is not factory-wired and the individual nameplates are visible in accordance with 430.7(D)(2), the conductor ampacity shall be determined in accordance with 430.24.

### 430.26 Feeder Demand Factor.

Where reduced heating of the conductors results from motors operating on duty-cycle, intermittently, or from all motors not operating at one time, the authority having jurisdiction may grant permission for feeder conductors to have an ampacity less than specified in
430.24, provided the conductors have sufficient ampacity for the maximum load determined in accordance with the sizes and number of motors supplied and the character of their loads and duties.

> [!info] Informational Note:
> Demand factors determined in the design of new facilities can often be validated against actual historical experience from similar installations.

### 430.27 Capacitors with Motors.

Where capacitors are installed in motor circuits, conductors shall comply with 460.8 and 460.9.

### 430.28 Feeder Taps.

Feeder tap conductors shall have an ampacity not less than that required by Part II, shall terminate in a branch-circuit protective device, and, in addition, shall meet one of the following requirements:

* (1) Be enclosed either by an enclosed controller or by a raceway, be not more than 3.0 m (10 ft) in length, and, for field installation, be protected by an overcurrent device on the line side of the tap conductor, the rating or setting of which shall not exceed
1000 percent of the tap conductor ampacity

* (2) Have an ampacity of at least one-third that of the feeder conductors, be suitably protected from physical damage or enclosed in a raceway, and be not more than 7.5 m (25 ft) in length

* (3) Have an ampacity not less than the feeder conductors

> [!important] Exception:
> Feeder taps over 7.5 m (25 ft) long. In high-bay manufacturing buildings \[over 11 m (35 ft) high at walls\], where conditions of maintenance and supervision ensure that only qualified persons service the systems, conductors tapped to a feeder shall be permitted to be not over 7.5 m (25 ft) long horizontally and not over 30.0 m (100 ft) in total length where all of the following conditions are met:

* (1) The ampacity of the tap conductors is not less than one-third that of the feeder conductors.

* (2) The tap conductors terminate with a single circuit breaker or a single set of fuses complying with (1) Part IV, where the load-side conductors are a branch circuit, or (2) Part V, where the load-side conductors are a feeder.

* (3) The tap conductors are suitably protected from physical damage and are installed in raceways.

* (4) The tap conductors are continuous from end-to-end and contain no splices.

* (5) The tap conductors shall be 6 AWG copper or 4 AWG aluminum or larger.

* (6) The tap conductors shall not penetrate walls, floors, or ceilings.

* (7) The tap shall not be made less than 9.0 m (30 ft) from the floor.

### 430.29 Constant Voltage Direct-Current Motors — Power Resistors.

Conductors connecting the motor controller to separately mounted power accelerating and dynamic braking resistors in the armature circuit shall have an ampacity not less than the value calculated from Table 430.29 using motor full-load current. If an armature shunt resistor is used, the power accelerating resistor conductor ampacity shall be calculated using the total of motor full-load current and armature shunt resistor current.

Armature shunt resistor conductors shall have an ampacity of not less than that calculated from Table 430.29 using rated shunt resistor current as full-load current.

#### Table 430.29 Conductor Rating Factors for Power Resistors

Time in Seconds

Ampacity of Conductor in Percent of Full-Load Current

On Off
On 5, Off 75 | 35
On 10, Off 70 | 45
On 15, Off 75 | 55
On 15, Off 45 | 65
On 15, Off 30 | 75
On 15, Off 15 | 85

Continuous Duty 110

## Part III. Motor and Branch-Circuit Overload Protection

### 430.31 General.

Part III specifies overload devices intended to protect motors, motor-control apparatus, and motor branch-circuit conductors against excessive heating due to motor overloads and failure to start.

> [!info] Informational Note No. 1:
> See Informative Annex D, Example No. D8.

> [!info] Informational Note No. 2:
> See the definition of Overload in Article 100.

These provisions shall not require overload protection where a power loss would cause a hazard, such as in the case of fire pumps.

> [!info] Informational Note:
> For protection of fire pump supply conductors, see 695.7.

Part III shall not apply to motor circuits rated over 1000 volts, nominal.

> [!info] Informational Note:
> For over 1000 volts, nominal, see Part XI.

### 430.32 Continuous-Duty Motors.

#### 430.32(A) More Than 1 Horsepower.

Each motor used in a continuous duty application and rated more than 1 hp shall be protected against overload by one of the means in 430.32(A)(1) through (A)(4).

##### 430.32(A)(1) Separate Overload Device.

A separate overload device that is responsive to motor current. This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate full-load current rating:

Motors with a marked service factor 1.15 or greater 125%

Motors with a marked temperature rise 40°C or less 125%

All other motors 115%

Modification of this value shall be permitted as provided in 430.32(C). For a multispeed motor, each winding connection shall be considered separately.

Where a separate motor overload device is connected so that it does not carry the total current designated on the motor nameplate, such as for wye-delta starting, the proper percentage of nameplate current applying to the selection or setting of the overload device shall be clearly designated on the equipment, or the manufacturer’s selection table shall take this into account.

> [!info] Informational Note:
> Where power factor correction capacitors are installed on the load side of the motor overload device, see 460.9.

##### 430.32(A)(2) Thermal Protector or Electronically Protected.

A thermal protector integral with the motor shall be approved for use with the motor it protects on the basis that it will prevent dangerous overheating of the motor due to overload and failure to start. An electronically protected motor shall be approved for use on the basis that it will prevent dangerous overheating due to the failure of the electronic control, overload, or failure to start the motor. The ultimate trip current of a thermally or electronically protected motor shall not exceed the following percentage of motor full-load current given in Table 430.248, Table 430.249, and Table 430.250:

|                                                                |      |
| -------------------------------------------------------------- | ---- |
| Motor full-load current 9 amperes or less                      | 170% |
| Motor full-load current from 9.1 to, and including, 20 amperes | 156% |
| Motor full-load current greater than 20 amperes                | 140% |

If the motor current-interrupting device is separate from the motor and its control circuit is operated by a protective device integral with the motor, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor.

##### 430.32(A)(3) Integral with Motor.

A protective device integral with a motor that will protect the motor against damage due to failure to start shall be permitted if the motor is part of an approved assembly that does not normally subject the motor to overloads.

##### 430.32(A)(4) Larger Than 1500 Horsepower.

For motors larger than 1500 hp, a protective device having embedded temperature detectors that cause current to the motor to be interrupted when the motor attains a temperature rise greater than marked on the nameplate in an ambient temperature of 40°C.

#### 430.32(B) One Horsepower or Less, Automatically Started.

Any motor of 1 hp or less that is started automatically shall be protected against overload by one of the following means.

##### 430.32(B)(1) Separate Overload Device.

By a separate overload device following the requirements of 430.32(A)(1).

For a multispeed motor, each winding connection shall be considered separately. Modification of this value shall be permitted as provided in 430.32(C).

##### 430.32(B)(2) Thermal Protector or Electronically Protected.

A thermal protector integral with the motor shall be approved for use with the motor that it protects on the basis that it will prevent dangerous overheating of the motor due to overload and failure to start. An electronically protected motor shall be approved for use on the basis that it will prevent dangerous overheating due to the failure of the electronic control, overload, or failure to start the motor.

Where the motor current-interrupting device is separate from the motor and its control circuit is operated by a protective device integral with the motor, it shall be arranged so that the opening of the control circuit results in interruption of current to the motor.

##### 430.32(B)(3) Integral with Motor.

A protective device integral with a motor that protects the motor against damage due to failure to start shall be permitted (1) if the motor is part of an approved assembly that does not subject the motor to overloads, or (2) if the assembly is also equipped with other safety controls (such as the safety combustion controls on a domestic oil burner) that protect the motor against damage due to failure to start.

Where the assembly has safety controls that protect the motor, it shall be so indicated on the nameplate of the assembly where it will be visible after installation.

##### 430.32(B)(4) Impedance-Protected.

If the impedance of the motor windings is sufficient to prevent overheating due to failure to start, the motor shall be permitted to be protected as specified in 430.32(D)(2)(a) for manually started motors if the motor is part of an approved assembly in which the motor will limit itself so that it will not be dangerously overheated.

> [!info] Informational Note:
> Many ac motors of less than 1⁄20 hp, such as clock motors, series motors, and so forth, and also some larger motors such as torque motors, come within this classification. It does not include split-phase motors having automatic switches that disconnect the starting windings.

#### 430.32(C) Selection of Overload Device.

Where the sensing element or setting or sizing of the overload device selected in accordance with 430.32(A)(1) and 430.32(B)(1) is not sufficient to start the motor or to carry the load, higher size sensing elements or incremental settings or sizing shall be permitted to be used, provided the trip current of the overload device does not exceed the following percentage of motor nameplate full-load current rating:

|                                                    |      |
| -------------------------------------------------- | ---- |
| Motors with marked service factor 1.15 or greater  | 140% |
| Motors with a marked temperature rise 40°C or less | 140% |
| All other motors                                   | 130% |

If not shunted during the starting period of the motor as provided in 430.35, the overload device shall have sufficient time delay to permit the motor to start and accelerate its load.

> [!info] Informational Note:
> A Class 20 overload relay will provide a longer motor acceleration time than a Class 10 or Class 10A overload relay.

A Class 30 overload relay will provide a longer motor acceleration time than a Class 20 overload relay. Use of a higher class overload relay may preclude the need for selection of a higher trip current.

#### 430.32(D) One Horsepower or Less, Nonautomatically Started.

##### 430.32(D)(1) Permanently Installed.

Overload protection shall be in accordance with 430.32(B).

##### 430.32(D)(2) Not Permanently Installed.

* (a) Within Sight from Controller. Overload protection shall be permitted to be furnished by the branch-circuit short-circuit and ground-fault protective device; such device, however, shall not be larger than that specified in Part IV of Article 430.

> [!important] Exception:
> Any such motor shall be permitted on a nominal 120-volt branch circuit protected at not over 20 amperes.

* (b) Not Within Sight from Controller. Overload protection shall be in accordance with 430.32(B).

#### 430.32(E) Wound-Rotor Secondaries.

The secondary circuits of wound-rotor ac motors, including conductors, controllers, resistors, and so forth, shall be permitted to be protected against overload by the motor-overload device.

### 430.33 Intermittent and Similar Duty.

A motor used for a condition of service that is inherently short-time, intermittent, periodic, or varying duty, as illustrated by Table
430.22(E), shall be permitted to be protected against overload by the branch-circuit short-circuit and ground-fault protective device, provided the protective device rating or setting does not exceed that specified in Table 430.52.

Any motor application shall be considered to be for continuous duty unless the nature of the apparatus it drives is such that the motor cannot operate continuously with load under any condition of use.

### 430.35 Shunting During Starting Period.

#### 430.35(A) Nonautomatically Started.

For a nonautomatically started motor, the overload protection shall be permitted to be shunted or cut out of the circuit during the starting period of the motor if the device by which the overload protection is shunted or cut out cannot be left in the starting position and if fuses or inverse time circuit breakers rated or set at not over 400 percent of the full-load current of the motor are located in the circuit so as to be operative during the starting period of the motor.

#### 430.35(B) Automatically Started.

The motor overload protection shall not be shunted or cut out during the starting period if the motor is automatically started.

> [!important] Exception:
> The motor overload protection shall be permitted to be shunted or cut out during the starting period on an automatically started motor where the following apply:

* (1) The motor starting period exceeds the time delay of available motor overload protective devices, and

* (2) Listed means are provided to perform the following:
    * a. Sense motor rotation and automatically prevent the shunting or cutout in the event that the motor fails to start, and
    * b. Limit the time of overload protection shunting or cutout to less than the locked rotor time rating of the protected motor, and
    * c. Provide for shutdown and manual restart if motor running condition is not reached.

### 430.36 Fuses — In Which Conductor.

Where fuses are used for motor overload protection, a fuse shall be inserted in each ungrounded conductor and also in the grounded conductor if the supply system is 3-wire, 3-phase ac with one conductor grounded.

### 430.37 Devices Other Than Fuses — In Which Conductor.

Where devices other than fuses are used for motor overload protection, Table 430.37 shall govern the minimum allowable number and location of overload units such as trip coils or relays.

#### Table 430.37 Overload Units

Kind of

Motor Supply System

Number and Location of Overload Units, Such as Trip

Coils or Relays
1-phase ac or dc
2-wire, 1-phase ac or dc ungrounded 1 in either conductor
1-phase ac or dc
2-wire, 1-phase ac or dc, one conductor grounded
1 in ungrounded conductor
1-phase ac or dc
3-wire, 1-phase ac or dc, grounded neutral conductor
1 in either ungrounded conductor
1-phase ac Any 3-phase 1 in ungrounded conductor
2-phase ac 3-wire, 2-phase ac, ungrounded 2, one in each phase
2-phase ac 3-wire, 2-phase ac, one conductor grounded
2 in ungrounded conductors
2-phase ac 4-wire, 2-phase ac, grounded or ungrounded
2, one for each phase in ungrounded conductors
2-phase ac Grounded neutral or 5-wire, 2-phase ac, ungrounded
2, one for each phase in any ungrounded phase wire
3-phase ac Any 3-phase 3, one in each phase*
*Exception: An overload unit in each phase shall not be required where overload protection is provided by other approved means.

### 430.38 Number of Conductors Opened by Overload Device.

Motor overload devices, other than fuses or thermal protectors, shall simultaneously open a sufficient number of ungrounded conductors to interrupt current flow to the motor.

### 430.39 Motor Controller as Overload Protection.

A motor controller shall also be permitted to serve as an overload device if the number of overload units complies with Table 430.37 and if these units are operative in both the starting and running position in the case of a dc motor, and in the running position in the case of an ac motor.

### 430.40 Overload Relays.

Overload relays and other devices for motor overload protection that are not capable of opening short circuits or ground faults shall be protected by fuses or circuit breakers with ratings or settings in accordance with 430.52 or by a motor short-circuit protector in accordance with 430.52.

> [!important] Exception:
> Where approved for group installation and marked to indicate the maximum size of fuse or inverse time circuit breaker by which they must be protected, the overload devices shall be protected in accordance with this marking.

### 430.42 Motors on General-Purpose Branch Circuits.

Overload protection for motors used on general-purpose branch circuits as permitted in Article 210 shall be provided as specified in
430.42(A), (B), (C), or (D).

#### 430.42(A) Not over 1 Horsepower.

One or more motors without individual overload protection shall be permitted to be connected to a general-purpose branch circuit only where the installation complies with the limiting conditions specified in 430.32(B) and 430.32(D) and 430.53(A)(1) and (A)(2).

#### 430.42(B) Over 1 Horsepower.

Motors of ratings larger than specified in 430.53(A) shall be permitted to be connected to general-purpose branch circuits only where each motor is protected by overload protection selected to protect the motor as specified in 430.32. Both the controller and the motor overload device shall be approved for group installation with the short-circuit and ground-fault protective device selected in accordance with 430.53.

#### 430.42(C) Cord-and Plug-Connected.

Where a motor is connected to a branch circuit by means of an attachment plug and a receptacle or a cord connector, and individual overload protection is omitted as provided in 430.42(A), the rating of the attachment plug and receptacle or cord connector shall not exceed 15 amperes at 125 volts or 250 volts. Where individual overload protection is required as provided in 430.42(B) for a motor or motor-operated appliance that is attached to the branch circuit through an attachment plug and a receptacle or a cord connector, the overload device shall be an integral part of the motor or of the appliance. The rating of the attachment plug and receptacle or the cord connector shall determine the rating of the circuit to which the motor may be connected, as provided in 210.21(B).

#### 430.42(D) Time Delay.

The branch-circuit short-circuit and ground-fault protective device protecting a circuit to which a motor or motor-operated appliance is connected shall have sufficient time delay to permit the motor to start and accelerate its load.

### 430.43 Automatic Restarting.

A motor overload device that can restart a motor automatically after overload tripping shall not be installed unless approved for use with the motor it protects. A motor overload device that can restart a motor automatically after overload tripping shall not be installed if automatic restarting of the motor can result in injury to persons.

### 430.44 Orderly Shutdown.

If immediate automatic shutdown of a motor by a motor overload protective device(s) would introduce additional or increased hazard(s) to a person(s) and continued motor operation is necessary for safe shutdown of equipment or process, a motor overload sensing device(s) complying with Part III of this article shall be permitted to be connected to a supervised alarm instead of causing immediate interruption of the motor circuit, so that corrective action or an orderly shutdown can be initiated.

## Part IV. Motor Branch-Circuit Short-Circuit and Ground-Fault Protection

### 430.51 General.

Part IV specifies devices intended to protect the motor branch-circuit conductors, the motor control apparatus, and the motors against overcurrent due to short circuits or ground faults. These rules add to or amend Article 240. The devices specified in Part IV do not include the types of devices required by 210.8, 230.95, and 590.6.

> [!info] Informational Note:
> See Informative Annex D, Example D8.

Part IV shall not apply to motor circuits rated over 1000 volts, nominal.

> [!info] Informational Note:
> For over 1000 volts, nominal, see Part XI.

### 430.52 Rating or Setting for Individual Motor Circuit.

#### 430.52(A) General.

The motor branch-circuit short-circuit and ground-fault protective device shall comply with 430.52(B) and either 430.52(C) or (D), as applicable.

#### 430.52(B) All Motors.

The motor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor.

#### 430.52(C) Rating or Setting.

##### 430.52(C)(1) In Accordance with Table 430.52.

A protective device that has a rating or setting not exceeding the value calculated according to the values given in Table 430.52 shall be used.

##### Table 430.52 Maximum Rating or Setting of Motor Branch-Circuit Short-Circuit and Ground-Fault

Protective Devices

Type of Motor

Percentage of Full-Load Current

Nontime

Delay

Fuse

Dual Element
(Time-Delay)

Fuse

Instantaneous

Trip

Breaker

Inverse

Time

Breaker

Single-phase motors 300 175 800 250

AC polyphase motors other than wound-rotor 300 175 800 250

Squirrel cage — other than Design B energy-efficient 300 175 800 250

Design B energy-efficient 300 175 1100 250

Synchronous 300 175 800 250

Wound-rotor 150 150 800 150

DC (constant voltage) 150 150 250 150

Note: For certain exceptions to the values specified, see 430.54.

The values in the Nontime Delay Fuse column apply to time-delay Class CC fuses.

The values given in the last column also cover the ratings of nonadjustable inverse time types of circuit breakers that may be modified as in 430.52(C)(1), Exceptions No. 1 and No. 2.

Synchronous motors of the low-torque, low-speed type (usually 450 rpm or lower), such as are used to drive reciprocating compressors, pumps, and so forth, that start unloaded, do not require a fuse rating or circuit-breaker setting in excess of 200 percent of full-load current.

> [!important] Exception No. 1:
> Where the values for branch-circuit short-circuit and ground-fault protective devices determined by Table 430.52 do not correspond to the standard sizes or ratings of fuses, nonadjustable circuit breakers, thermal protective devices, or possible settings of adjustable circuit breakers, a higher size, rating, or possible setting that does not exceed the next higher standard ampere rating shall be permitted.

> [!important] Exception No. 2:
> Where the rating specified in Table 430.52, or the rating modified by Exception No. 1, is not sufficient for the starting current of the motor:

* (1) The rating of a nontime-delay fuse not exceeding 600 amperes or a time-delay Class CC fuse shall be permitted to be increased but shall in no case exceed 400 percent of the full-load current.

* (2) The rating of a time-delay (dual-element) fuse shall be permitted to be increased but shall in no case exceed 225 percent of the full-load current.

* (3) The rating of an inverse time circuit breaker shall be permitted to be increased but shall in no case exceed 400 percent for fullload currents of 100 amperes or less or 300 percent for full-load currents greater than 100 amperes.
1 1 2
3
1
2
3

* (4) The rating of a fuse of 601–6000 ampere classification shall be permitted to be increased but shall in no case exceed
300 percent of the full-load current.

> [!info] Informational Note:
> See Informative Annex D, Example D8, and Figure 430.1.

##### 430.52(C)(2) Overload Relay Table.

Where maximum branch-circuit short-circuit and ground-fault protective device ratings are shown in the manufacturer’s overload relay table for use with a motor controller or are otherwise marked on the equipment, they shall not be exceeded even if higher values are allowed as shown above.

##### 430.52(C)(3) Instantaneous Trip Circuit Breaker.

An instantaneous trip circuit breaker shall be used only if adjustable and if part of a listed combination motor controller having coordinated motor overload and short-circuit and ground-fault protection in each conductor, and the setting is adjusted to no more than the value specified in Table 430.52.

> [!info] Informational Note No. 1:
> Instantaneous trip circuit breakers are also known as motor-circuit protectors (MCPs).

> [!info] Informational Note No. 2:
> For the purpose of this article, instantaneous trip circuit breakers may include a damping means to accommodate a transient motor inrush current without nuisance tripping of the circuit breaker.

> [!important] Exception No. 1:
> Where the setting specified in Table 430.52 is not sufficient for the starting current of the motor, the setting of an instantaneous trip circuit breaker shall be permitted to be increased but shall in no case exceed 1300 percent of the motor full-load current for other than Design B energy-efficient motors and no more than 1700 percent of motor full-load current for Design B energyefficient motors. Trip settings above 800 percent for other than Design B energy-efficient motors and above 1100 percent for Design B energy-efficient motors shall be permitted where the need has been demonstrated by engineering evaluation. In such cases, it shall not be necessary to first apply an instantaneous-trip circuit breaker at 800 percent or 1100 percent.

> [!info] Informational Note:
> For additional information on the requirements for a motor to be classified “energy efficient,” see NEMA MG 1-2016,

Motors and Generators, Part 12.59.

> [!important] Exception No. 2:
> Where the motor full-load current is 8 amperes or less, the setting of the instantaneous-trip circuit breaker with a continuous current rating of 15 amperes or less in a listed combination motor controller that provides coordinated motor branch-circuit overload and short-circuit and ground-fault protection shall be permitted to be increased to the value marked on the controller.

##### 430.52(C)(4) Multispeed Motor.

For a multispeed motor, a single short-circuit and ground-fault protective device shall be permitted for two or more windings of the motor, provided the rating of the protective device does not exceed the above applicable percentage of the nameplate rating of the smallest winding protected.

> [!important] Exception:
> For a multispeed motor, a single short-circuit and ground-fault protective device shall be permitted to be used and sized according to the full-load current of the highest current winding, where all of the following conditions are met:

* (1) Each winding is equipped with individual overload protection sized according to its full-load current.

* (2) The branch-circuit conductors supplying each winding are sized according to the full-load current of the highest full-load current winding.

* (3) The controller for each winding has a horsepower rating not less than that required for the winding having the highest horsepower rating.

##### 430.52(C)(5) Power Electronic Devices.

Semiconductor fuses intended for the protection of electronic devices shall be permitted in lieu of devices listed in Table 430.52 for power electronic devices, associated electromechanical devices (such as bypass contactors and isolation contactors), and conductors in a solid-state motor controller system, provided that the marking for replacement fuses is provided adjacent to the fuses.

##### 430.52(C)(6) Self-Protected Combination Controller.

A listed self-protected combination controller shall be permitted in lieu of the devices specified in Table 430.52. Adjustable instantaneous-trip settings shall not exceed 1300 percent of full-load motor current for other than Design B energy-efficient motors and not more than 1700 percent of full-load motor current for Design B energy-efficient motors.

> [!info] Informational Note:
> Proper application of self-protected combination controllers on 3-phase systems, other than solidly grounded wye, particularly on corner grounded delta systems, considers the self-protected combination controllers' individual pole-interrupting capability.

##### 430.52(C)(7) Motor Short-Circuit Protector.

A motor short-circuit protector shall be permitted in lieu of devices listed in Table 430.52 if the motor short-circuit protector is part of a listed combination motor controller having coordinated motor overload protection and short-circuit and ground-fault protection in each conductor and it will open the circuit at currents exceeding 1300 percent of motor full-load current for other than Design B energyefficient motors and 1700 percent of motor full-load motor current for Design B energy-efficient motors.

> [!info] Informational Note:
> A motor short-circuit protector, as used in this section, is a fused device and is not an instantaneous trip circuit breaker.

#### 430.52(D) Torque Motors.

Torque motor branch circuits shall be protected at the motor nameplate current rating in accordance with 240.4(B).

### 430.53 Several Motors or Loads on One Branch Circuit.

Two or more motors or one or more motors and other loads shall be permitted to be connected to the same branch circuit under conditions specified in 430.53(D) and in 430.53(A), (B), or (C). The branch-circuit protective device shall be fuses or inverse time circuit breakers.

#### 430.53(A) Not Over 1 Horsepower.

Several motors, each not exceeding 1 hp in rating, shall be permitted on a nominal 120-volt branch circuit protected at not over 20 amperes or a branch circuit of 1000 volts, nominal, or less, protected at not over 15 amperes, if all of the following conditions are met:

* (1) The full-load rating of each motor does not exceed 6 amperes.

* (2) The rating of the branch-circuit short-circuit and ground-fault protective device marked on any of the controllers is not exceeded.

* (3) Individual overload protection conforms to 430.32.

#### 430.53(B) If Smallest Rated Motor Protected.

If the branch-circuit short-circuit and ground-fault protective device is selected not to exceed that allowed by 430.52 for the smallest rated motor, two or more motors or one or more motors and other load(s), with each motor having individual overload protection, shall be permitted to be connected to a branch circuit where it can be determined that the branch-circuit short-circuit and ground-fault protective device will not open under the most severe normal conditions of service that might be encountered.

#### 430.53(C) Other Group Installations.

Two or more motors of any rating or one or more motors and other load(s), with each motor having individual overload protection, shall be permitted to be connected to one branch circuit where the motor controller(s) and overload device(s) are (1) installed as a listed factory assembly and the motor branch-circuit short-circuit and ground-fault protective device either is provided as part of the assembly or is specified by a marking on the assembly, or (2) the motor branch-circuit short-circuit and ground-fault protective device, the motor controller(s), and overload device(s) are field-installed as separate assemblies listed for such use and provided with manufacturers’ instructions for use with each other, and (3) all of the following conditions are complied with:

* (1) Each motor overload device is either (a) listed for group installation with a specified maximum rating of fuse, inverse time circuit breaker, or both, or (b) selected such that the ampere rating of the motor-branch short-circuit and ground-fault protective device does not exceed that permitted by 430.52 for that individual motor overload device and corresponding motor load.

* (2) Each motor controller is either (a) listed for group installation with a specified maximum rating of fuse, circuit breaker, or both, or

* (b) selected such that the ampere rating of the motor-branch short-circuit and ground-fault protective device does not exceed that permitted by 430.52 for that individual controller and corresponding motor load.

* (3) Each circuit breaker is listed and is of the inverse time type.

* (4) The branch circuit shall be protected by fuses or inverse time circuit breakers having a rating not exceeding that specified in
430.52 for the highest rated motor connected to the branch circuit plus an amount equal to the sum of the full-load current ratings of all other motors and the ratings of other loads connected to the circuit. Where this calculation results in a rating less than the ampacity of the branch-circuit conductors, it shall be permitted to increase the maximum rating of the fuses or circuit breaker to a value not exceeding that permitted by 240.4(B).

* (5) The branch-circuit fuses or inverse time circuit breakers are not larger than allowed by 430.40 for the overload relay protecting the smallest rated motor of the group.

* (6) Overcurrent protection for loads other than motor loads shall be in accordance with Parts I through VII of Article 240.

> [!info] Informational Note:
> See 110.10 for circuit impedance and other characteristics.

#### 430.53(D) Single Motor Taps.

For group installations described above, the conductors of any tap supplying a single motor shall not be required to have an individual branch-circuit short-circuit and ground-fault protective device, provided they comply with one of the following:

* (1) No conductor to the motor shall have an ampacity less than that of the branch-circuit conductors.

* (2) No conductor to the motor shall have an ampacity less than one-third that of the branch-circuit conductors, with a minimum in accordance with 430.22. The conductors from the point of the tap to the motor overload device shall be not more than 7.5 m
(25 ft) long and be protected from physical damage by being enclosed in an approved raceway or by use of other approved means.

* (3) Conductors from the point of the tap from the branch circuit to a listed manual motor controller additionally marked “Suitable for

Tap Conductor Protection in Group Installations,” or to a branch-circuit protective device, shall be permitted to have an ampacity not less than one-tenth the rating or setting of the branch-circuit short-circuit and ground-fault protective device. The conductors from the controller to the motor shall have an ampacity in accordance with 430.22. The conductors from the point of the tap to the controller(s) shall (1) be suitably protected from physical damage and enclosed either by an enclosed controller or by a raceway and be not more than 3 m (10 ft) long or (2) have an ampacity not less than that of the branch-circuit conductors.

* (4) Conductors from the point of the tap from the branch circuit to a listed manual motor controller additionally marked “Suitable for

Tap Conductor Protection in Group Installations,” or to a branch-circuit protective device, shall be permitted to have an ampacity not less than one-third that of the branch-circuit conductors. The conductors from the controller to the motor shall have an ampacity in accordance with 430.22. The conductors from the point of the tap to the controller(s) shall (1) be suitably protected from physical damage and enclosed either by an enclosed controller or by a raceway and be not more than 7.5 m (25 ft) long or

* (2) have an ampacity not less than that of the branch-circuit conductors.

### 430.54 Multimotor and Combination-Load Equipment.

The rating of the branch-circuit short-circuit and ground-fault protective device for multimotor and combination-load equipment shall not exceed the rating marked on the equipment in accordance with 430.7(D).

### 430.55 Combined Overcurrent Protection.

Motor branch-circuit short-circuit and ground-fault protection and motor overload protection shall be permitted to be combined in a single protective device where the rating or setting of the device provides the overload protection specified in 430.32.

### 430.56 Branch-Circuit Protective Devices — In Which Conductor.

Branch-circuit protective devices shall comply with 240.15.

### 430.57 Size of Fuseholder.

Where fuses are used for motor branch-circuit short-circuit and ground-fault protection, the fuseholders shall not be of a smaller size than required to accommodate the fuses specified by Table 430.52.

> [!important] Exception:
> Where fuses having time delay appropriate for the starting characteristics of the motor are used, it shall be permitted to use fuseholders sized to fit the fuses that are used.

### 430.58 Rating of Circuit Breaker.

A circuit breaker for motor branch-circuit short-circuit and ground-fault protection shall have a current rating in accordance with 430.52 and 430.110.

## Part V. Motor Feeder Short-Circuit and Ground-Fault Protection

### 430.61 General.

Part V specifies protective devices intended to protect feeder conductors supplying motors against overcurrents due to short circuits or grounds.

> [!info] Informational Note:
> See Informative Annex D, Example D8.

### 430.62 Rating or Setting — Motor Load.

#### 430.62(A) Specific Load.

A feeder supplying a specific fixed motor load(s) and consisting of conductor sizes based on 430.24 shall be provided with a protective device having a rating or setting not greater than the largest rating or setting of the branch-circuit short-circuit and ground-fault protective device for any motor supplied by the feeder \[based on the maximum permitted value for the specific type of a protective device in accordance with 430.52, or 440.22(A) for hermetic refrigerant motor-compressors\], plus the sum of the full-load currents of the other motors of the group.

Where the same rating or setting of the branch-circuit short-circuit and ground-fault protective device is used on two or more of the branch circuits supplied by the feeder, one of the protective devices shall be considered the largest for the above calculations.

> [!important] Exception No. 1:
> Where one or more instantaneous trip circuit breakers or motor short-circuit protectors are used for motor branch-circuit short-circuit and ground-fault protection as permitted in 430.52(C), the procedure provided above for determining the maximum rating of the feeder protective device shall apply with the following provision: For the purpose of the calculation, each instantaneous trip circuit breaker or motor short-circuit protector shall be assumed to have a rating not exceeding the maximum percentage of motor fullload current permitted by Table 430.52 for the type of feeder protective device employed.

> [!important] Exception No. 2:
> Where the feeder overcurrent protective device also provides overcurrent protection for a motor control center, the provisions of 430.94 shall apply.

> [!info] Informational Note:
> See Informative Annex D, Example D8.

#### 430.62(B) Other Installations.

Where feeder conductors have an ampacity greater than required by 430.24, the rating or setting of the feeder overcurrent protective device shall be permitted to be based on the ampacity of the feeder conductors.

### 430.63 Rating or Setting — Motor Load and Other Load(s).

Where a feeder supplies a motor load and other load(s), the feeder protective device shall have a rating not less than that required for the sum of the other load(s) plus the following:

* (1) For a single motor, the rating permitted by 430.52

* (2) For a single hermetic refrigerant motor-compressor, the rating permitted by 440.22

* (3) For two or more motors, the rating permitted by 430.62

> [!important] Exception:
> Where the feeder overcurrent device provides the overcurrent protection for a motor control center, the provisions of 430.94 shall apply.

## Part VI. Motor Control Circuits

### 430.71 General.

Part VI contains modifications of the general requirements and applies to the particular conditions of motor control circuits.

### 430.72 Overcurrent Protection.

#### 430.72(A) General.

A motor control circuit tapped from the load side of a motor branch-circuit short-circuit and ground-fault protective device(s) and functioning to control the motor(s) connected to that branch circuit shall be protected against overcurrent in accordance with 430.72.

Such a tapped control circuit shall not be considered to be a branch circuit and shall be permitted to be protected by either a supplementary or branch-circuit overcurrent protective device(s). A motor control circuit other than such a tapped control circuit shall be protected against overcurrent in accordance with 725.43 or the notes to Table 11(A) and Table 11(B) in Chapter 9, as applicable.

#### 430.72(B) Conductor Protection.

The overcurrent protection for conductors shall be provided as specified in 430.72(B)(1) or (B)(2).

> [!important] Exception No. 1:
> Where the opening of the control circuit would create a hazard as, for example, the control circuit of a fire pump motor, and the like, conductors of control circuits shall require only short-circuit and ground-fault protection and shall be permitted to be protected by the motor branch-circuit short-circuit and ground-fault protective device(s).

> [!important] Exception No. 2:
> Conductors supplied by the secondary side of a single-phase transformer having only a two-wire (single-voltage) secondary shall be permitted to be protected by overcurrent protection provided on the primary (supply) side of the transformer, provided this protection does not exceed the value determined by multiplying the appropriate maximum rating of the overcurrent device for the secondary conductor from Table 430.72(B) by the secondary-to-primary voltage ratio. Transformer secondary conductors (other than two-wire) shall not be considered to be protected by the primary overcurrent protection.

##### 430.72(B)(1) Separate Overcurrent Protection.

Where the motor branch-circuit short-circuit and ground-fault protective device does not provide protection in accordance with
430.72(B)(2), separate overcurrent protection shall be provided. The overcurrent protection shall not exceed the values specified in Column A of Table 430.72(B).

##### 430.72(B)(2) Branch-Circuit Overcurrent Protective Device.

Conductors shall be permitted to be protected by the motor branch-circuit short-circuit and ground-fault protective device and shall require only short-circuit and ground-fault protection. Where the conductors do not extend beyond the motor control equipment enclosure, the rating of the protective device(s) shall not exceed the value specified in Column B of Table 430.72(B). Where the conductors extend beyond the motor control equipment enclosure, the rating of the protective device(s) shall not exceed the value specified in Column C of Table 430.72(B).

##### Table 430.72(B) Maximum Rating of Overcurrent Protective Device in Amperes

Column A

Separate Protection

Protection Provided by Motor Branch-Circuit

Protective Device(s)

Provided

Column B

Conductors Within

Enclosure

Column C

Conductors Extend

Beyond

Enclosure

Control Circuit

Conductor Size
(AWG) Copper

Aluminum or

Copper-Clad

Aluminum Copper

Aluminum or

Copper-Clad

Aluminum Copper

Aluminum or

Copper-Clad

Aluminum

Column A

Separate Protection

Provided

Protection Provided by Motor Branch-Circuit

Protective Device(s)

Column B

Conductors Within

Enclosure

Column C

Conductors Extend

Beyond

Enclosure

Control Circuit

Conductor Size
(AWG) Copper

Aluminum or

Copper-Clad

Aluminum Copper

Aluminum or

Copper-Clad

Aluminum Copper

Aluminum or

Copper-Clad

Aluminum
18 7 — 25 — 7 —
16 10 — 40 — 10 —
14 (Note 1) — 100 — 45 —
12 (Note 1) (Note 1) 120 100 60 45
10 (Note 1) (Note 1) 160 140 90 75

Larger than 10 (Note 1) (Note 1) (Note 2) (Note 2) (Note 3) (Note 3)

Notes:
1. Value specified in 310.15 as applicable.
2. 400 percent of value specified in Table 310.17 for 60°C conductors.
3. 300 percent of value specified in Table 310.16 for 60°C conductors.

#### 430.72(C) Control Circuit Transformer.

Where a motor control circuit transformer is provided, the transformer shall be protected in accordance with 430.72(C)(1), (C)(2), (C)(3),
(C)(4), or (C)(5).

> [!important] Exception:
> Overcurrent protection shall be omitted where the opening of the control circuit would create a hazard as, for example, the control circuit of a fire pump motor and the like.

##### 430.72(C)(1) Compliance with Article 725.

Where the transformer supplies a Class 1 power-limited circuit, Class 2, or Class 3 remote-control circuit complying with the requirements of Article 725, protection shall comply with Article 725.

##### 430.72(C)(2) Compliance with Article 450.

Protection shall be permitted to be provided in accordance with 450.3.

##### 430.72(C)(3) Less Than 50 Volt-Amperes.

Control circuit transformers rated less than 50 volt-amperes (VA) and that are an integral part of the motor controller and located within the motor controller enclosure shall be permitted to be protected by primary overcurrent devices, impedance limiting means, or other inherent protective means.

##### 430.72(C)(4) Primary Less Than 2 Amperes.

Where the control circuit transformer rated primary current is less than 2 amperes, an overcurrent device rated or set at not more than
500 percent of the rated primary current shall be permitted in the primary circuit.

##### 430.72(C)(5) Other Means.

Protection shall be permitted to be provided by other approved means.

### 430.73 Protection of Conductors from Physical Damage.

Where damage to a motor control circuit would constitute a hazard, all conductors of such a remote motor control circuit that are outside the control device itself shall be installed in a raceway or be otherwise protected from physical damage.

### 430.74 Electrical Arrangement of Control Circuits.

Where one conductor of the motor control circuit is grounded, the motor control circuit shall be arranged so that a ground fault in the control circuit remote from the motor controller will (1) not start the motor and (2) not bypass manually operated shutdown devices or automatic safety shutdown devices.

### 430.75 Disconnection.

#### 430.75(A) General.

Motor control circuits shall be arranged so that they will be disconnected from all sources of supply when the disconnecting means is in the open position. The disconnecting means shall be permitted to consist of two or more separate devices, one of which disconnects the motor and the controller from the source(s) of power supply for the motor, and the other(s), the motor control circuit(s) from its power supply. Where separate devices are used, they shall be located immediately adjacent to each other.

> [!important] Exception No. 1:
> Where more than 12 motor control circuit conductors are required to be disconnected, the disconnecting means shall be permitted to be located other than immediately adjacent to each other where all of the following conditions are complied with:

* (1) Access to energized parts is limited to qualified persons in accordance with Part XII of this article.

* (2) A warning sign is permanently located on the outside of each equipment enclosure door or cover permitting access to the live parts in the motor control circuit(s), warning that motor control circuit disconnecting means are remotely located and specifying the location and identification of each disconnect. Where energized parts are not in an equipment enclosure as permitted by
430.232 and 430.233, an additional warning sign(s) shall be located where visible to persons who may be working in the area of the energized parts.

> [!important] Exception No. 2:
> The motor control circuit disconnecting means shall be permitted to be remote from the motor controller power supply disconnecting means where the opening of one or more motor control circuit disconnecting means is capable of resulting in potentially unsafe conditions for personnel or property and the conditions of items (1) and (2) of Exception No. 1 are complied with.

#### 430.75(B) Control Transformer in Controller Enclosure.

Where a transformer or other device is used to obtain a reduced voltage for the motor control circuit and is located in the controller enclosure, such transformer or other device shall be connected to the load side of the disconnecting means for the motor control circuit.

## Part VII. Motor Controllers

### 430.81 General.

Part VII is intended to require suitable controllers for all motors.

#### 430.81(A) Stationary Motor of 1⁄8 Horsepower or Less.

For a stationary motor rated at 1⁄8 hp or less that is normally left running and is constructed so that it cannot be damaged by overload or failure to start, such as clock motors and the like, the branch-circuit disconnecting means shall be permitted to serve as the controller.

#### 430.81(B) Portable Motor of 1⁄3 Horsepower or Less.

For a portable motor rated at 1⁄3 hp or less, the controller shall be permitted to be an attachment plug and receptacle or cord connector.

### 430.82 Controller Design.

#### 430.82(A) Starting and Stopping.

Each controller shall be capable of starting and stopping the motor it controls and shall be capable of interrupting the locked-rotor current of the motor.

#### 430.82(B) Autotransformer.

An autotransformer starter shall provide an “off” position, a running position, and at least one starting position. It shall be designed so that it cannot rest in the starting position or in any position that will render the overload device in the circuit inoperative.

#### 430.82(C) Rheostats.

Rheostats shall be in compliance with the following:

* (1) Motor-starting rheostats shall be designed so that the contact arm cannot be left on intermediate segments. The point or plate on which the arm rests when in the starting position shall have no electrical connection with the resistor.

* (2) Motor-starting rheostats for dc motors operated from a constant voltage supply shall be equipped with automatic devices that will interrupt the supply before the speed of the motor has fallen to less than one-third its normal rate.

### 430.83 Ratings.

The controller shall have a rating as specified in 430.83(A), unless otherwise permitted in 430.83(B) or (C), or as specified in (D), under the conditions specified.

#### 430.83(A) General.

##### 430.83(A)(1) Horsepower Ratings.

Controllers, other than inverse time circuit breakers and molded case switches, shall have horsepower ratings at the application voltage not lower than the horsepower rating of the motor.

##### 430.83(A)(2) Circuit Breaker.

A branch-circuit inverse time circuit breaker rated in amperes shall be permitted as a controller for all motors. Where this circuit breaker is also used for overload protection, it shall conform to the appropriate provisions of this article governing overload protection.

##### 430.83(A)(3) Molded Case Switch.

A molded case switch rated in amperes shall be permitted as a controller for all motors.

#### 430.83(B) Small Motors.

Devices as specified in 430.81(A) and (B) shall be permitted as a controller.

#### 430.83(C) Stationary Motors of 2 Horsepower or Less.

For stationary motors rated at 2 hp or less and 300 volts or less, the controller shall be permitted to be either of the following:

* (1) A general-use switch having an ampere rating not less than twice the full-load current rating of the motor

* (2) On ac circuits, a general-use snap switch suitable only for use on ac (not general-use ac–dc snap switches) where the motor full-load current rating is not more than 80 percent of the ampere rating of the switch

#### 430.83(D) Torque Motors.

For torque motors, the controller shall have a continuous-duty, full-load current rating not less than the nameplate current rating of the motor. For a motor controller rated in horsepower but not marked with the foregoing current rating, the equivalent current rating shall be determined from the horsepower rating by using Table 430.247, Table 430.248, Table 430.249, or Table 430.250.

#### 430.83(E) Voltage Rating.

A controller with a straight voltage rating, for example, 240 volts or 480 volts, shall be permitted to be applied in a circuit in which the nominal voltage between any two conductors does not exceed the controller’s voltage rating. A controller with a slash rating, for example, 120/240 volts or 480Y/277 volts, shall only be applied in a solidly grounded circuit in which the nominal voltage to ground from any conductor does not exceed the lower of the two values of the controller’s voltage rating and the nominal voltage between any two conductors does not exceed the higher value of the controller’s voltage rating.

### 430.84 Need Not Open All Conductors.

The controller shall not be required to open all conductors to the motor.

> [!important] Exception:
> Where the controller serves also as a disconnecting means, it shall open all ungrounded conductors to the motor as provided in 430.111.

### 430.85 In Grounded Conductors.

One pole of the controller shall be permitted to be placed in a permanently grounded conductor, provided the controller is designed so that the pole in the grounded conductor cannot be opened without simultaneously opening all conductors of the circuit.

### 430.87 Number of Motors Served by Each Controller.

Each motor shall be provided with an individual controller.

> [!important] Exception No. 1: ^87-ex1
> For motors rated 1000 volts or less, a single controller rated at not less than the equivalent horsepower, as determined in accordance with 430.110(C)(1), of all the motors in the group shall be permitted to serve the group under any of the following conditions:

* (1) Where a number of motors drive several parts of a single machine or piece of apparatus, such as metal and woodworking machines, cranes, hoists, and similar apparatus

* (2) Where a group of motors is under the protection of one overcurrent device as permitted in 430.53(A)

* (3) Where a group of motors is located in a single room within sight from the controller location

> [!important] Exception No. 2: ^87-ex1
> A branch-circuit disconnecting means serving as the controller as allowed in 430.81(A) shall be permitted to serve more than one motor.

### 430.88 Adjustable-Speed Motors.

Adjustable-speed motors that are controlled by means of field regulation shall be equip ped and connected so that they cannot be started under a weakened field.

> [!important] Exception:
> Starting under a weakened field shall be permitted where the motor is designed for such starting.

### 430.89 Speed Limitation.

Machines of the following types shall be provided with speed-limiting devices or other speed-limiting means:

* (1) Separately excited dc motors

* (2) Series motors

* (3) Motor-generators and converters that can be driven at excessive speed from the dc end, as by a reversal of current or decrease in load

> [!important] Exception:
> Separate speed-limiting devices or means shall not be required under either of the following conditions:

* (1) Where the inherent characteristics of the machines, the system, or the load and the mechanical connection thereto are such as to safely limit the speed

* (2) Where the machine is always under the manual control of a qualified operator

### 430.90 Combination Fuseholder and Switch as Controller.

The rating of a combination fuseholder and switch used as a motor controller shall be such that the fuseholder will accommodate the size of the fuse specified in Part III of this article for motor overload protection.

> [!important] Exception:
> Where fuses having time delay appropriate for the starting characteristics of the motor are used, fuseholders of smaller size than specified in Part III of this article shall be permitted.

## Part VIII. Motor Control Centers

### 430.92 General.

Part VIII covers motor control centers instal led for the control of motors, lighting, and power circuits.

### 430.94 Overcurrent Protection.

Motor control centers shall be provided with overcurrent protection in accordance with Parts I, II, and VIII of Article 240. The ampere rating or setting of the overcurrent protective device shall not exceed the rating of the common power bus. This protection shall be provided by (1) an overcurrent protective device located ahead of the motor control center or (2) a main overcurrent protective device located within the motor control center.

### 430.95 Service Equipment.

Where used as service equipment, each motor control center shall be provided with a single main disconnecting means to disconnect all ungrounded service conductors.

> [!important] Exception:
> A second service disconnect shall be permitted to supply additional equipment.

Where a grounded conductor is provided, the motor control center shall be provided with a main bonding jumper, sized in accordance with 250.28(D), within one of the sections for connecting the grounded conductor, on its supply side, to the motor control center equipment ground bus.

> [!important] Exception:
> High-impedance grounded neutral systems shall be permitted to be connected as provided in 250.36.

### 430.96 Grounding.

Multisection motor control centers shall be connected together with an equipment grounding conductor or an equivalent equipment grounding bus sized in accordance with Table 250.122. Equipment grounding conductors shall be connected to this equipment grounding bus or to a grounding termination point provided in a single-section motor control center.

### 430.97 Busbars and Conductors.

#### 430.97(A) Support and Arrangement.

Busbars shall be protected from physical damage and be held firmly in place. Other than for required interconnections and control wiring, only those conductors that are intended for termination in a vertical section shall be located in that section.

> [!important] Exception:
> Conductors shall be permitted to travel horizontally through vertical sections where such conductors are isolated from the busbars by a barrier.

#### 430.97(B) Phase Arrangement.

The phase arrangement on 3-phase horizontal common power and vertical buses shall be A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the motor control center. The B phase shall be that phase having the higher voltage to ground on 3-phase, 4-wire, delta-connected systems. Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.

> [!important] Exception:
> Rear-mounted units connected to a vertical bus that is common to front-mounted units shall be permitted to have a C, B, A phase arrangement where properly identified.

#### 430.97(C) Minimum Wire-Bending Space.

The minimum wire-bending space at the motor control center terminals and minimum gutter space shall be as required in Article 312.

#### 430.97(D) Spacings.

Spacings between motor control center bus terminals and other bare metal parts shall not be less than specified in Table 430.97(D).

##### Table 430.97(D) Minimum Spacing Between Bare Metal Parts

Nominal

Voltage

Opposite Polarity Where Mounted on the Same Surface

Opposite Polarity Where

Held Free in Air

Live Parts to

Ground mm in. mm in. mm in.

Not over 125 volts, nominal
19.1 3⁄4 12.7 1⁄2 12.7 1⁄2

Not over 250 volts, nominal
31.8 11⁄4 19.1 3⁄4 12.7 1⁄2

Not over 600 volts, nominal
50.8 2 25.4 1 25.4 1

#### 430.97(E) Barriers.

Barriers shall be placed in all service-entrance motor control centers to isolate service busbars and terminals from the remainder of the motor control center.

### 430.98 Marking.

#### 430.98(A) Motor Control Centers.

Motor control centers shall be marked according to 110.21, and the marking shall be plainly visible after installation. Marking shall also include common power bus current rating and motor control center short-circuit current rating.

#### 430.98(B) Motor Control Units.

Motor control units in a motor control center shall comply with 430.8.

### 430.99 Available Fault Current.

The available fault current at the motor control center and the date the available fault current calculation was performed shall be documented and made available to those authorized to inspect, install, or maintain the installation.

## Part IX. Disconnecting Means

### 430.101 General.

Part IX is intended to require disconnecting means capable of disconnecting motors and controllers from the circuit.

### 430.102 Location.

#### 430.102(A) Controller.

An individual disconnecting means shall be provided for each controller and shall disconnect the controller. The disconnecting means shall be located in sight from the controller location.

> [!important] Exception No. 1:
> For motor circuits over 1000 volts, nominal, a controller disconnecting means lockable in accordance with 110.25 shall be permitted to be out of sight of the controller, provided that the controller is marked with a warning label giving the location of the disconnecting means.

> [!important] Exception No. 2:
> A single disconnecting means shall be permitted for a group of coordinated controllers that drive several parts of a single machine or piece of apparatus. The disconnecting means shall be located in sight from the controllers, and both the disconnecting means and the controllers shall be located in sight from the machine or apparatus.

> [!important] Exception No. 3:
> The disconnecting means shall not be required to be in sight from valve actuator motor (VAM) assemblies containing the controller where such a location introduces additional or increased hazards to persons or property and conditions (1) and (2) are met.

* (1) The valve actuator motor assembly is marked with a warning label giving the location of the disconnecting means.

* (2) The disconnecting means is lockable in accordance with 110.25.

#### 430.102(B) Motor.

A disconnecting means shall be provided for a motor in accordance with 430.102(B)(1) or (B)(2).

##### 430.102(B)(1) Separate Motor Disconnect.

A disconnecting means for the motor shall be located in sight from the motor location and the driven machinery location.

##### 430.102(B)(2) Controller Disconnect.

The controller disconnecting means required in accordance with 430.102(A) shall be permitted to serve as the disconnecting means for the motor if it is in sight from the motor location and the driven machinery location.

Exception to (1) and (2): The disconnecting means for the motor shall not be required under either condition (1) or condition (2), which follow, provided that the controller disconnecting means required in 430.102(A) is lockable in accordance with 110.25.

* (1) Where such a location of the disconnecting means for the motor is impracticable or introduces additional or increased hazards to persons or property

> [!info] Informational Note:
> Some examples of increased or additional hazards include, but are not limited to, motors rated in excess of
100 hp, multimotor equipment, submersible motors, motors associated with adjustable speed drives, and motors located in hazardous (classified) locations.

* (2) In industrial installations, with written safety procedures, where conditions of maintenance and supervision ensure that only qualified persons service the equipment

> [!info] Informational Note:
> For information on lockout/tagout procedures, see NFPA 70E-2015, Standard for Electrical Safety in the Workplace.

### 430.103 Operation.

The disconnecting means shall open all ungrounded supply conductors and shall be designed so that no pole can be operated independently. The disconnecting means shall be permitted in the same enclosure with the controller. The disconnecting means shall be designed so that it cannot be closed automatically.

> [!info] Informational Note:
> See 430.113 for equipment receiving energy from more than one source.

### 430.104 To Be Indicating.

The disconnecting means shall plainly indicate whether it is in the open (off) or closed (on) position.

### 430.105 Grounded Conductors.

One pole of the disconnecting means shall be permitted to disconnect a permanently grounded conductor, provided the disconnecting means is designed so that the pole in the grounded conductor cannot be opened without simultaneously disconnecting all conductors of the circuit.

### 430.107 Readily Accessible.

At least one of the disconnecting means shall be readily accessible.

### 430.108 Every Disconnecting Means.

Every disconnecting means in the motor circuit between the point of attachment to the feeder or branch circuit and the point of connection to the motor shall comply with the requirements of 430.109 and 430.110.

### 430.109 Type.

The disconnecting means shall be a type specified in 430.109(A), unless otherwise permitted in 430.109(B) through (G), under the conditions specified.

#### 430.109(A) General.

##### 430.109(A)(1) Motor Circuit Switch.

A listed motor-circuit switch rated in horsepower.

##### 430.109(A)(2) Molded Case Circuit Breaker.

A listed molded case circuit breaker.

##### 430.109(A)(3) Molded Case Switch.

A listed molded case switch.

##### 430.109(A)(4) Instantaneous Trip Circuit Breaker.

An instantaneous trip circuit breaker that is part of a listed combination motor controller.

##### 430.109(A)(5) Self-Protected Combination Controller.

Listed self-protected combination controller.

##### 430.109(A)(6) Manual Motor Controller.

Listed manual motor controllers additionally marked “Suitable as Motor Disconnect” shall be permitted as a disconnecting means where installed between the final motor branch-circuit short-circuit protective device and the motor. Listed manual motor controllers additionally marked “Suitable as Motor Disconnect” shall be permitted as disconnecting means on the line side of the fuses permitted in
430.52(C)(5). In this case, the fuses permitted in 430.52(C)(5) shall be considered supplementary fuses, and suitable branch-circuit short-circuit and ground-fault protective devices shall be installed on the line side of the manual motor controller additionally marked
“Suitable as Motor Disconnect.”

##### 430.109(A)(7) System Isolation Equipment.

System isolation equipment shall be listed for disconnection purposes. System isolation equipment shall be installed on the load side of the overcurrent protection and its disconnecting means. The disconnecting means shall be one of the types permitted by 430.109(A)(1) through (A)(3).

#### 430.109(B) Stationary Motors of 1⁄8 Horsepower or Less.

For stationary motors of 1⁄8 hp or less, the branch-circuit overcurrent device shall be permitted to serve as the disconnecting means.

#### 430.109(C) Stationary Motors of 2 Horsepower or Less.

For stationary motors rated at 2 hp or less and 300 volts or less, the disconnecting means shall be permitted to be one of the devices specified in (1), (2), or (3):

* (1) A general-use switch having an ampere rating not less than twice the full-load current rating of the motor

* (2) On ac circuits, a general-use snap switch suitable only for use on ac (not general-use ac–dc snap switches) where the motor full-load current rating is not more than 80 percent of the ampere rating of the switch

* (3) A listed manual motor controller having a horsepower rating not less than the rating of the motor and marked “Suitable as Motor

Disconnect”

#### 430.109(D) Autotransformer-Type Controlled Motors.

For motors of over 2 hp to and including 100 hp, the separate disconnecting means required for a motor with an autotransformer-type controller shall be permitted to be a general-use switch where all of the following provisions are met:

* (1) The motor drives a generator that is provided with overload protection.

* (2) The controller is capable of interrupting the locked-rotor current of the motors, is provided with a no voltage release, and is provided with running overload protection not exceeding 125 percent of the motor full-load current rating.

* (3) Separate fuses or an inverse time circuit breaker rated or set at not more than 150 percent of the motor full-load current is provided in the motor branch circuit.

#### 430.109(E) Isolating Switches.

For stationary motors rated at more than 40 hp dc or 100 hp ac, the disconnecting means shall be permitted to be a general-use or isolating switch where plainly marked “Do not operate under load.”

#### 430.109(F) Cord-and-Plug-Connected Motors.

For a cord-and-plug-connected motor, a horsepower-rated attachment plug and receptacle, flanged surface inlet and cord connector, or attachment plug and cord connector having ratings no less than the motor ratings shall be permitted to serve as the disconnecting means. Horsepower-rated attachment plugs, flanged surface inlets, receptacles, or cord connectors shall not be required for cord-andplug-connected appliances in accordance with 422.33, room air conditioners in accordance with 440.63, or portable motors rated 1⁄3 hp or less.

#### 430.109(G) Torque Motors.

For torque motors, the disconnecting means shall be permitted to be a general-use switch.

### 430.110 Ampere Rating and Interrupting Capacity.

#### 430.110(A) General.

The disconnecting means for motor circuits rated 1000 volts, nominal, or less shall have an ampere rating not less than 115 percent of the full-load current rating of the motor.

> [!important] Exception:
> A listed unfused motor-circuit switch having a horsepower rating not less than the motor horsepower shall be permitted to have an ampere rating less than 115 percent of the full-load current rating of the motor.

#### 430.110(B) For Torque Motors.

Disconnecting means for a torque motor shall have an ampere rating of at least 115 percent of the motor nameplate current.

#### 430.110(C) For Combination Loads.

Where two or more motors are used together or where one or more motors are used in combination with other loads, such as resistance heaters, and where the combined load may be simultaneous on a single disconnecting means, the ampere and horsepower ratings of the combined load shall be determined as follows.

##### 430.110(C)(1) Horsepower Rating.

The rating of the disconnecting means shall be determined from the sum of all currents, including resistance loads, at the full-load condition and also at the locked-rotor condition. The combined full-load current and the combined locked-rotor current so obtained shall be considered as a single motor for the purpose of this requirement as follows.

The full-load current equivalent to the horsepower rating of each motor shall be selected from Table 430.247, Table 430.248, Table 430.249, or Table 430.250. These full-load currents shall be added to the rating in amperes of other loads to obtain an equivalent full-load current for the combined load.

The locked-rotor current equivalent to the horsepower rating of each motor shall be selected from Table 430.251(A) or Table
430.251(B). The locked-rotor currents shall be added to the rating in amperes of other loads to obtain an equivalent locked-rotor current for the combined load. Where two or more motors or other loads cannot be started simultaneously, the largest sum of locked-rotor currents of a motor or group of motors that can be started simultaneously and the full-load currents of other concurrent loads shall be permitted to be used to determine the equivalent locked-rotor current for the simultaneous combined loads. In cases where different current ratings are obtained when applying these tables, the largest value obtained shall be used.

> [!important] Exception:
> Where part of the concurrent load is resistance load, and where the disconnecting means is a switch rated in horsepower and amperes, the switch used shall be permitted to have a horsepower rating that is not less than the combined load of the motor(s), if the ampere rating of the switch is not less than the locked-rotor current of the motor(s) plus the resistance load.

##### 430.110(C)(2) Ampere Rating.

The ampere rating of the disconnecting means shall not be less than 115 percent of the sum of all currents at the full-load condition determined in accordance with 430.110(C)(1).

> [!important] Exception:
> A listed nonfused motor-circuit switch having a horsepower rating equal to or greater than the equivalent horsepower of the combined loads, determined in accordance with 430.110(C)(1), shall be permitted to have an ampere rating less than 115 percent of the sum of all currents at the full-load condition.

##### 430.110(C)(3) Small Motors.

For small motors not covered by Table 430.247, Table 430.248, Table 430.249, or Table 430.250, the locked-rotor current shall be assumed to be six times the full-load current.

### 430.111 Switch or Circuit Breaker as Both Controller and Disconnecting Means.

A switch or circuit breaker shall be permitted to be used as both the controller and disconnecting means if it complies with 430.111(A) and is one of the types specified in 430.111(B).

#### 430.111(A) General.

The switch or circuit breaker complies with the requirements for controllers specified in 430.83, opens all ungrounded conductors to the motor, and is protected by an overcurrent device in each ungrounded conductor (which shall be permitted to be the branch-circuit fuses). The overcurrent device protecting the controller shall be permitted to be part of the controller assembly or shall be permitted to be separate. An autotransformer-type controller shall be provided with a separate disconnecting means.

#### 430.111(B) Type.

The device shall be one of the types specified in 430.111(B)(1), (B)(2), or (B)(3).

##### 430.111(B)(1) Air-Break Switch.

An air-break switch, operable directly by applying the hand to a lever or handle.

##### 430.111(B)(2) Inverse Time Circuit Breaker.

An inverse time circuit breaker operable directly by applying the hand to a lever or handle. The circuit breaker shall be permitted to be both power and manually operable.

##### 430.111(B)(3) Oil Switch.

An oil switch used on a circuit whose rating does not exceed 1000 volts or 100 amperes, or by special permission on a circuit exceeding this capacity where under expert supervision. The oil switch shall be permitted to be both power and manually operable.

### 430.112 Motors Served by Single Disconnecting Means.

Each motor shall be provided with an individual disconnecting means.

> [!important] Exception: ^112-ex
> A single disconnecting means shall be permitted to serve a group of motors under any one of the conditions of (1), (2), and (3). The single disconnecting means shall be rated in accordance with 430.110(C).
> * (1) Where a number of motors drive several parts of a single machine or piece of apparatus, such as metal- and woodworking machines, cranes, and hoists.
> * (2) Where a group of motors is under the protection of one set of branch-circuit protective devices as permitted by 430.53(A).
> * (3) Where a group of motors is in a single room within sight from the location of the disconnecting means.

### 430.113 Energy from More Than One Source.

Motor and motor-operated equipment receiving electric energy from more than one source shall be provided with disconnecting means from each source of electric energy immediately adjacent to the equipment served. Each source shall be permitted to have a separate disconnecting means. Where multiple disconnecting means are provided, a permanent warning sign shall be provided on or adjacent to each disconnecting means.

> [!important] Exception No. 1:
> Where a motor receives electric energy from more than one source, the disconnecting means for the main power supply to the motor shall not be required to be immediately adjacent to the motor, provided that the controller disconnecting means is lockable in accordance with 110.25.

> [!important] Exception No. 2:
> A separate disconnecting means shall not be required for a Class 2 remote-control circuit conforming with Article 725, rated not more than 30 volts, and isolated and ungrounded.

## Part X. Adjustable-Speed Drive Systems

### 430.120 General.

The installation provisions of Part I through Part IX are applicable unless modified or supplemented by Part X.

### 430.122 Conductors — Minimum Size and Ampacity.

#### 430.122(A) Branch/Feeder Circuit Conductors.

Circuit conductors supplying power conversion equipment included as part of an adjustable-speed drive system shall have an ampacity not less than 125 percent of the rated input current to the power conversion equipment.

> [!info] Informational Note No. 1:
> Power conversion equipment can have multiple power ratings and corresponding input currents.

> [!info] Informational Note No. 2:
> Circuit conductors on the output of an adjustable-speed drive system are susceptible to breakdown under certain conditions due to the characteristics of the output waveform of the drive. Factors affecting the conductors include but are not limited to the output voltage, frequency, and current, the length of the conductors, the spacing between the conductors, and the dielectric strength of the conductor insulation. Methods to mitigate breakdown include consideration of one or more of these factors.

#### 430.122(B) Output Conductors.

The conductors between the power conversion equipment and the motor shall have an ampacity equal to or larger than 125 percent of the motor full-load current as determined by 430.6(A) or (B).

> [!important] Exception:
> If the power conversion equipment is listed and marked as “Suitable for Output Motor Conductor Protection,” the conductor between the power conversion equipment and the motor shall have an ampacity equal to or greater than the larger of:

* (1) 125 percent of the motor full load current as determined by 430.6(A) or (B)

* (2) The ampacity of the minimum conductor size marked on the power conversion equipment

> [!info] Informational Note:
> The minimum ampacity required of output conductors is often different than that of the conductors supplying the power conversion equipment. See 430.130 and 430.131 for branch circuit protection requirements.

#### 430.122(C) Bypass Device.

For an adjustable-speed drive system that utilizes a bypass device, the conductor ampacity shall not be less than required by 430.6.

The ampacity of circuit conductors supplying power conversion equipment included as part of an adjustable-speed drive system that utilizes a bypass device shall be the larger of either of the following:

* (1) 125 percent of the rated input current to the power conversion equipment

* (2) 125 percent of the motor full-load current rating as determined by 430.6

#### 430.122(D) Several Motors or a Motor and Other Loads.

Conductors supplying several motors or a motor and other loads, including power conversion equipment, shall have ampacity in accordance with 430.24, using the rated input current of the power conversion equipment for purposes of calculating ampacity.

### 430.124 Overload Protection.

Overload protection of the motor shall be provided.

#### 430.124(A) Included in Power Conversion Equipment.

Where the power conversion equipment is marked to indicate that motor overload protection is included, additional overload protection shall not be required.

#### 430.124(B) Bypass Circuits.

For adjustable-speed drive systems that utilize a bypass device to allow motor operation at rated full-load speed, motor overload protection as described in Article 430, Part III, shall be provided in the bypass circuit.

#### 430.124(C) Multiple Motor Applications.

For multiple motor application, individual motor overload protection shall be provided in accordance with Article 430, Part III.

### 430.126 Motor Overtemperature Protection.

#### 430.126(A) General.

Adjustable-speed drive systems shall protect against motor overtemperature conditions where the motor is not rated to operate at the nameplate rated current over the speed range required by the application. This protection shall be provided in addition to the conductor protection required in 430.32. Protection shall be provided by one of the following means.

* (1) Motor thermal protector in accordance with 430.32

* (2) Adjustable-speed drive system with load and speed-sensitive overload protection and thermal memory retention upon shutdown or power loss

> [!important] Exception to (2):
> Thermal memory retention upon shutdown or power loss is not required for continuous duty loads.

* (3) Overtemperature protection relay utilizing thermal sensors embedded in the motor and meeting the requirements of 430.126(A)(2)

* (4) Thermal sensor embedded in the motor whose communications are received and acted upon by an adjustable-speed drive system

> [!info] Informational Note:
> The relationship between motor current and motor temperature changes when the motor is operated by an adjustable-speed drive. In certain applications, overheating of motors can occur when operated at reduced speed, even at current levels less than a motor’s rated full-load current. The overheating can be the result of reduced motor cooling when its shaft-mounted fan is operating less than rated nameplate RPM. As part of the analysis to determine whether overheating will occur, it is necessary to consider the continuous torque capability curves for the motor given the application requirements. This will assist in determining whether the motor overload protection will be able, on its own, to provide protection against overheating. These overheating protection requirements are only intended to apply to applications where an adjustable-speed drive, as defined in Article 100, is used.

For motors that utilize external forced air or liquid cooling systems, overtemperature can occur if the cooling system is not operating.

Although this issue is not unique to adjustable speed applications, externally cooled motors are most often encountered with such applications. In these instances, overtemperature protection using direct temperature sensing is recommended \[i.e., 430.126(A)(1), (A)
(3), or (A)(4)\], or additional means should be provided to ensure that the cooling system is operating (flow or pressure sensing, interlocking of adjustable-speed drive system and cooling system, etc.).

#### 430.126(B) Multiple Motor Applications.

For multiple motor applications, individual motor overtemperature protection shall be provided as required in 430.126(A).

#### 430.126(C) Automatic Restarting and Orderly Shutdown.

430.43 and 430.44 shall apply to the motor overtemperature protection means.

### 430.128 Disconnecting Means.

The disconnecting means shall be permitted to be in the incoming line to the conversion equipment and shall have a rating not less than 115 percent of the rated input current of the conversion unit.

### 430.130 Branch-Circuit Short-Circuit and Ground-Fault Protection for Single Motor Circuits Containing Power Conversion Equipment.

#### 430.130(A) Circuits Containing Power Conversion Equipment.

Circuits containing power conversion equipment shall be protected by a branch circuit short-circuit and ground-fault protective device in accordance with all of the following:

* (1) The rating and type of protection shall be determined by 430.52(C)(1), (C)(3), (C)(5), or (C)(6), using the full-load current rating of the motor load as determined by 430.6(A) or (B).

Exception to 1: The rating and type of protection shall be permitted to be determined by Table 430.52 using the power conversion equipment’s rated input current where the power conversion equipment is listed and marked “Suitable for Output Motor Conductor Protection.”

> [!info] Informational Note No. 1:
> Motor conductor branch circuit short-circuit and ground-fault protection from the power conversion equipment to the motor is provided by power conversion equipment that is listed and marked “Suitable for Output Motor

Conductor Protection.”

> [!info] Informational Note No. 2:
> A motor branch circuit using power conversion equipment, including equipment listed and marked
“Suitable for Output Motor Conductor Protection,” includes the input circuit to the power conversion equipment.

* (2) Where maximum branch circuit short-circuit and ground-fault protective ratings are stipulated for specific device types in the manufacturer's instructions for the power conversion equipment or are otherwise marked on the equipment, they shall not be exceeded even if higher values are permitted by 430.130(A)(1).

* (3) A self-protected combination controller shall only be permitted where specifically identified in the manufacturer’s instructions for the power conversion equipment or if otherwise marked on the equipment.

> [!info] Informational Note:
> The type of protective device, its rating, and its setting are often marked on or provided with the power conversion equipment.

* (4) Where an instantaneous trip circuit breaker or semiconductor fuses are permitted in accordance with the drive manufacturer’s instructions for use as the branch circuit short-circuit and ground-fault protective device for listed power conversion equipment, they shall be provided as an integral part of a single listed assembly incorporating both the protective device and power conversion equipment.

#### 430.130(B) Bypass Circuit/Device.

Branch-circuit short-circuit and ground-fault protection shall also be provided for a bypass circuit/device(s). Where a single branch-circuit short-circuit and ground-fault protective device is provided for circuits containing both power conversion equipment and a bypass circuit, the branch-circuit protective device type and its rating or setting shall be in accordance with those determined for the power conversion equipment and for the bypass circuit/device(s) equipment.

### 430.131 Several Motors or Loads on One Branch Circuit Including Power Conversion Equipment.

For installations meeting all the requirements of 430.53 that include one or more power converters, the branch-circuit short-circuit and ground-fault protective fuses or inverse time circuit breakers shall be of a type and rating or setting permitted for use with the power conversion equipment using the full-load current rating of the connected motor load in accordance with 430.53. For the purposes of
430.53 and 430.131, power conversion equipment shall be considered to be a motor controller.

## Part XI. Over 1000 Volts, Nominal

### 430.221 General.

Part XI recognizes the additional hazard due to the use of higher voltages. It adds to or amends the other provisions of this article.

### 430.222 Marking on Controllers.

In addition to the marking required by 430.8, a controller shall be marked with the control voltage.

### 430.223 Raceway Connection to Motors.

Flexible metal conduit or liquidtight flexible metal conduit not exceeding 1.8 m (6 ft) in length shall be permitted to be employed for raceway connection to a motor terminal enclosure.

### 430.224 Size of Conductors.

Conductors supplying motors shall have an ampacity not less than the current at which the motor overload protective device(s) is selected to trip.

### 430.225 Motor-Circuit Overcurrent Protection.

#### 430.225(A) General.

Each motor circuit shall include coordinated protection to automatically interrupt overload and fault currents in the motor, the motorcircuit conductors, and the motor control apparatus.

> [!important] Exception:
> Where a motor is critical to an operation and the motor should operate to failure if necessary to prevent a greater hazard to persons, the sensing device(s) shall be permitted to be connected to a supervised annunciator or alarm instead of interrupting the motor circuit.

#### 430.225(B) Overload Protection.

##### 430.225(B)(1) Type of Overload Device.

Each motor shall be protected against dangerous heating due to motor overloads and failure to start by a thermal protector integral with the motor or external current-sensing devices, or both. Protective device settings for each motor circuit shall be determined under engineering supervision.

##### 430.225(B)(2) Wound-Rotor Alternating-Current Motors.

The secondary circuits of wound-rotor ac motors, including conductors, controllers, and resistors rated for the application, shall be considered as protected against overcurrent by the motor overload protection means.

##### 430.225(B)(3) Operation.

Operation of the overload interrupting device shall simultaneously disconnect all ungrounded conductors.

##### 430.225(B)(4) Automatic Reset.

Overload sensing devices shall not automatically reset after trip unless resetting of the overload sensing device does not cause automatic restarting of the motor or there is no hazard to persons created by automatic restarting of the motor and its connected machinery.

#### 430.225(C) Fault-Current Protection.

##### 430.225(C)(1) Type of Protection.

Fault-current protection shall be provided in each motor circuit as specified by either 430.225(C) (1) (a) or (C)(1)(b).

* (a) A circuit breaker of suitable type and rating arranged so that it can be serviced without hazard. The circuit breaker shall simultaneously disconnect all ungrounded conductors. The circuit breaker shall be permitted to sense the fault current by means of integral or external sensing elements.

* (b) Fuses of a suitable type and rating placed in each ungrounded conductor. Fuses shall be used with suitable disconnecting means, or they shall be of a type that can also serve as the disconnecting means. They shall be arranged so that they cannot be serviced while they are energized.

##### 430.225(C)(2) Reclosing.

Fault-current interrupting devices shall not automatically reclose the circuit.

> [!important] Exception:
> Automatic reclosing of a circuit shall be permitted where the circuit is exposed to transient faults and where such automatic reclosing does not create a hazard to persons.

##### 430.225(C)(3) Combination Protection.

Overload protection and fault-current protection shall be permitted to be provided by the same device.

### 430.226 Rating of Motor Control Apparatus.

The ultimate trip current of overcurrent (overload) relays or other motor-protective devices used shall not exceed 115 percent of the controller’s continuous current rating. Where the motor branch-circuit disconnecting means is separate from the controller, the disconnecting means current rating shall not be less than the ultimate trip setting of the overcurrent relays in the circuit.

### 430.227 Disconnecting Means.

The controller disconnecting means shall be lockable in accordance with [[nfpa-70_110_requirements#110.25 Lockable Disconnecting Means.|110.25]].

## Part XII. Protection of Live Parts — All Voltages

### 430.231 General.

Part XII specifies that live parts shall be protected in an approved manner for the hazard involved.

### 430.232 Where Required.

Exposed live parts of motors and controllers operating at 50 volts or more between terminals shall be guarded against accidental contact by enclosure or by location as follows:

* (1) By installation in a room or enclosure that is accessible only to qualified persons

* (2) By installation on a suitable balcony, gallery, or platform, elevated and arranged so as to exclude unqualified persons

* (3) By elevation 2.5 m (8 ft) or more above the floor

> [!important] Exception:
> Live parts of motors operating at more than 50 volts between terminals shall not require additional guarding for stationary motors that have commutators, collectors, and brush rigging located inside of motor-end brackets and not conductively connected to supply circuits operating at more than 150 volts to ground.

### 430.233 Guards for Attendants.

Where live parts of motors or controllers operating at over 50 volts to ground are guarded against accidental contact only by location as specified in 430.232, and where adjustment or other attendance may be necessary during the operation of the apparatus, suitable insulating mats or platforms shall be provided so that the attendant cannot readily touch live parts unless standing on the mats or platforms.

> [!info] Informational Note:
> For working space, see 110.26 and 110.34.

## Part XIII. Grounding — All Voltages

### 430.241 General.

Part XIII specifies the grounding of exposed non–current-carrying metal parts, likely to become energized, of motor and controller frames to prevent a voltage aboveground in the event of accidental contact between energized parts and frames. Insulation, isolation, or guarding are suitable alternatives to grounding of motors under certain conditions.

### 430.242 Stationary Motors.

The frames of stationary motors shall be grounded under any of the following conditions:

* (1) Where supplied by metal-enclosed wiring

* (2) Where in a wet location and not isolated or guarded

* (3) If in a hazardous (classified) location

* (4) If the motor operates with any terminal at over 150 volts to ground

Where the frame of the motor is not grounded, it shall be permanently and effectively insulated from the ground.

### 430.243 Portable Motors.

The frames of portable motors that operate over 150 volts to ground shall be guarded or grounded.

> [!info] Informational Note No. 1:
> See 250.114(4) for grounding of portable appliances in other than residential occupancies.

> [!info] Informational Note No. 2:
> See 250.119(C) for color of equipment grounding conductor.

> [!important] Exception No. 1:
> Listed motor-operated tools, listed motor-operated appliances, and listed motor-operated equipment shall not be required to be grounded where protected by a system of double insulation or its equivalent. Double-insulated equipment shall be distinctively marked.

> [!important] Exception No. 2:
> Listed motor-operated tools, listed motor-operated appliances, and listed motor-operated equipment connected by a cord and attachment plug other than those required to be grounded in accordance with 250.114.

### 430.244 Controllers.

Controller enclosures shall be connected to the equipment grounding conductor regardless of voltage. Controller enclosures shall have means for attachment of an equipment grounding conductor termination in accordance with 250.8.

> [!important] Exception:
> Enclosures attached to ungrounded portable equipment shall not be required to be grounded.

### 430.245 Method of Grounding.

Connection to the equipment grounding conductor shall be done in the manner specified in Part VI of Article 250.

#### 430.245(A) Grounding Through Terminal Housings.

Where the wiring to motors is metal-enclosed cable or in metal raceways, junction boxes to house motor terminals shall be provided, and the armor of the cable or the metal raceways shall be connected to them in the manner specified in 250.96(A) and 250.97.

#### 430.245(B) Separation of Junction Box from Motor.

The junction box required by 430.245(A) shall be permitted to be separated from the motor by not more than 1.8 m (6 ft), provided the leads to the motor are stranded conductors within Type AC cable, interlocked metal tape Type MC cable where listed and identified in accordance with 250.118(10)(a), or armored cord or are stranded leads enclosed in liquidtight flexible metal conduit, flexible metal conduit, intermediate metal conduit, rigid metal conduit, or electrical metallic tubing not smaller than metric designator 12 (trade size
3⁄8), the armor or raceway being connected both to the motor and to the box.

Liquidtight flexible nonmetallic conduit and rigid nonmetallic conduit shall be permitted to enclose the leads to the motor, provided the leads are stranded and the required equipment grounding conductor is connected to both the motor and to the box.

Where stranded leads are used, protected as specified above, each strand within the conductor shall be not larger than 10 AWG and shall comply with other requirements of this Code for conductors to be used in raceways.

#### 430.245(C) Grounding of Controller-Mounted Devices.

Instrument transformer secondaries and exposed non–current-carrying metal or other conductive parts or cases of instrument transformers, meters, instruments, and relays shall be grounded as specified in 250.170 through 250.178.

## Part XIV. Tables

### Table 430.247 Full-Load Current in Amperes, Direct-Current Motors ^t247

The following values of full-load currents* are for motors running at base speed.

Horsepower

Armature Voltage Rating*
90 Volts 120 Volts 180 Volts 240 Volts 500 Volts 550 Volts
1⁄4 4.0 3.1 2.0 1.6 — —
1⁄3 5.2 4.1 2.6 2.0 — —
1⁄2 6.8 5.4 3.4 2.7 — —
3⁄4 9.6 7.6 4.8 3.8 — —
1 12.2 9.5 6.1 4.7 — —
11⁄2 — 13.2 8.3 6.6 — —
2 — 17 10.8 8.5 — —
3 — 25 16 12.2 — —
5 — 40 27 20 — —
71⁄2 — 58 — 29 13.6 12.2
10 — 76 — 38 18 16
15 — — — 55 27 24
20 — — — 72 34 31
25 — — — 89 43 38
30 — — — 106 51 46
40 — — — 140 67 61
50 — — — 173 83 75
60 — — — 206 99 90
75 — — — 255 123 111
100 — — — 341 164 148
125 — — — 425 205 185
150 — — — 506 246 222
200 — — — 675 330 294
*These are average dc quantities.

### Table 430.248 Full-Load Currents in Amperes, Single-Phase Alternating-Current Motors ^t248

The following values of full-load currents are for motors running at usual speeds and motors with normal torque characteristics. The voltages listed are rated motor voltages. The currents listed shall be permitted for system voltage ranges of 110 to 120 and 220 to 240 volts.

Horsepower
115

Volts
200

Volts
208

Volts
230

Volts
1⁄6 4.4 2.5 2.4 2.2
1⁄4 5.8 3.3 3.2 2.9
1⁄3 7.2 4.1 4.0 3.6
1⁄2 9.8 5.6 5.4 4.9
3⁄4 13.8 7.9 7.6 6.9
1 16 9.2 8.8 8.0
11⁄2 20 11.5 11.0 10
2 24 13.8 13.2 12
3 34 19.6 18.7 17
5 56 32.2 30.8 28
71⁄2 80 46.0 44.0 40
10 100 57.5 55.0 50

### Table 430.249 Full-Load Current, Two-Phase Alternating-Current Motors (4-Wire) ^t249

The following values of full-load current are for motors running at speeds usual for belted motors and motors with normal torque characteristics. Current in the common conductor of a 2-phase, 3-wire system will be
1.41 times the value given. The voltages listed are rated motor voltages. The currents listed shall be permitted for system voltage ranges of
110 to 120, 220 to 240, 440 to 480, and 550 to
600 volts.

Horsepower

Induction-Type Squirrel Cage and

Wound Rotor (Amperes)
115

Volts
230

Volts
460

Volts
575

Volts
2300

Volts
1⁄2 4.0 2.0 1.0 0.8 —
3⁄4 4.8 2.4 1.2 1.0 —
1 6.4 3.2 1.6 1.3 —
11⁄2 9.0 4.5 2.3 1.8 —
2 11.8 5.9 3.0 2.4 —
3 — 8.3 4.2 3.3 —
5 — 13.2 6.6 5.3 —

Horsepower

Induction-Type Squirrel Cage and

Wound Rotor (Amperes)
115

Volts
230

Volts
460

Volts
575

Volts
2300

Volts
71⁄2 — 19 9.0 8.0 —
10 — 24 12 10 —
15 — 36 18 14 —
20 — 47 23 19 —
25 — 59 29 24 —
30 — 69 35 28 —
40 — 90 45 36 —
50 — 113 56 45 —
60 — 133 67 53 14
75 — 166 83 66 18
100 — 218 109 87 23
125 — 270 135 108 28
150 — 312 156 125 32
200 — 416 208 167 43

### Table 430.250 Full-Load Current, Three-Phase Alternating-Current Motors ^t250

The following values of full-load currents are typical for motors running at speeds usual for belted motors torque characteristics. The voltages listed are rated motor voltages. The currents listed shall be permitted ranges of 110 to 120, 220 to 240, 440 to 480, and 550 to 600 volts.

Horsepower

Induction-Type Squirrel Cage and Wound Rotor (Amperes)

Synchronou

Facto
115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts 2300 Volts 230 Volts 460 Vo
1⁄2 4.4 2.5 2.4 2.2 1.1 0.9 — — —
3⁄4 6.4 3.7 3.5 3.2 1.6 1.3 — — —
1 8.4 4.8 4.6 4.2 2.1 1.7 — — —
11⁄2 12.0 6.9 6.6 6.0 3.0 2.4 — — —
2 13.6 7.8 7.5 6.8 3.4 2.7 — — —
3 — 11.0 10.6 9.6 4.8 3.9 — — —
5 — 17.5 16.7 15.2 7.6 6.1 — — —
71⁄2 — 25.3 24.2 22 11 9 — — —
10 — 32.2 30.8 28 14 11 — — —
15 — 48.3 46.2 42 21 17 — — —
20 — 62.1 59.4 54 27 22 — — —
25 — 78.2 74.8 68 34 27 — 53 26
30 — 92 88 80 40 32 — 63 32
40 — 120 114 104 52 41 — 83 41
50 — 150 143 130 65 52 — 104 52
60 — 177 169 154 77 62 16 123 61
75 — 221 211 192 96 77 20 155 78
*For 90 and 80 percent power factor, the figures shall be multiplied by 1.1 and 1.25, respectively.

### Table 430.251(A) Conversion Table of Single-Phase Locked-Rotor Currents for Selection of Disconnecting Means and Controllers as Determined from Horsepower and Voltage Rating For use only with 430.110, 440.12, 440.41, and 455.8(C). ^t251a

Rated

Horsepower

Maximum Locked-Rotor Current in

Amperes, Single Phase
115 Volts 208 Volts 230 Volts
½ 58.8 32.5 29.4
¾ 82.8 45.8 41.4
1 96 53 48
1½ 120 66 60
2 144 80 72
3 204 113 102
5 336 186 168
7½ 480 265 240
10 1000 332 300

### Table 430.251(B) Conversion Table of Polyphase Design B, C, and D Maximum Locked-Rotor Currents for Selection of Disconnecting Means and Controllers as Determined from Horsepower and Voltage Rating and Design Letter For use only with 430.110, 440.12, 440.41, and 455.8(C). ^t251b

Rated

Horsepower

Maximum Motor Locked-Rotor Current in Amperes, Two- and Three-Phase, Design B, C, and D*
115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts

B, C, D B, C, D B, C, D B, C, D B, C, D B, C, D
1⁄2 40 23 22.1 20 10 8

Horsepower

Induction-Type Squirrel Cage and Wound Rotor (Amperes)

Synchronou

Facto
115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts 2300 Volts 230 Volts 460 Vo
100 — 285 273 248 124 99 26 202 101
125 — 359 343 312 156 125 31 253 126
150 — 414 396 360 180 144 37 302 151
200 552 528 480 240 192 49 400 201
250 — — — — 302 242 60 — —
300 — — — — 361 289 72 — —
350 — — — — 414 336 83 — —
400 — — — — 477 382 95 — —
450 — — — — 515 412 103 — —
500 — — — — 590 472 118 — —

Rated

Horsepower

Maximum Motor Locked-Rotor Current in Amperes, Two- and Three-Phase, Design B, C, and D*
115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts

B, C, D B, C, D B, C, D B, C, D B, C, D B, C, D
3⁄4 50 28.8 27.6 25 12.5 10
1 60 34.5 33 30 15 12
11⁄2 80 46 44 40 20 16
2 100 57.5 55 50 25 20
3 — 73.6 71 64 32 25.6
5 — 105.8 102 92 46 36.8
71⁄2 — 146 140 127 63.5 50.8
10 — 186.3 179 162 81 64.8
15 — 267 257 232 116 93
20 — 334 321 290 145 116
25 — 420 404 365 183 146
30 — 500 481 435 218 174
40 — 667 641 580 290 232
50 — 834 802 725 363 290
60 — 1001 962 870 435 348
75 — 1248 1200 1085 543 434
100 — 1668 1603 1450 725 580
125 — 2087 2007 1815 908 726
150 — 2496 2400 2170 1085 868
200 — 3335 3207 2900 1450 1160
250 — — — — 1825 1460
300 — — — — 2200 1760
350 — — — — 2550 2040
400 — — — — 2900 2320
450 — — — — 3250 2600
500 — — — — 3625 2900
*Design A motors are not limited to a maximum starting current or locked rotor current.
