vault backup: 2025-12-04 17:06:30
This commit is contained in:
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-186
@@ -23,21 +23,20 @@ This article covers the use, installation, construction specifications, and ampa
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The definitions in this section shall apply within this article and throughout the Code.
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Electrical Ducts.
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#### Electrical Ducts.
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Electrical conduits, or other raceways round in cross section, that are suitable for use underground or embedded in concrete.
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Medium Voltage Cable, Type MV.
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#### Medium Voltage Cable, Type MV.
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A single or multiconductor solid dielectric insulated cable rated 2001 volts up to and including 35,000 volts, nominal.
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Thermal Resistivity.
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#### Thermal Resistivity.
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As used in this Code, the heat transfer capability through a substance by conduction.
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> [!info] Informational Note:
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> Thermal resistivity is the reciprocal of thermal conductivity and is designated Rho, which is expressed in the units
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°C-cm/W.
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> Thermal resistivity is the reciprocal of thermal conductivity and is designated Rho, which is expressed in the units °C-cm/W.
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### 311.6 Listing Requirements.
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@@ -53,71 +52,21 @@ Type MV cables shall comply with the applicable provisions in 311.10(A) through
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Conductor application and insulation shall comply with Table 311.10(A).
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##### Table 311.10(A) Conductor Application and Insulation Rated 2001 Volts and Higher
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| Trade Name | Type Letter | Maximum Operating Temperature | Application Provision | Insulation | Outer Covering |
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| ------------------------------- |:----------------:|:-----------------------------:| --------------------- | ------------------------------ | ------------------------ |
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| Medium voltage solid dielectric | MV-90<br>MV-105* | 90°C<br>105°C | Dry or wet locations | Thermoplastic or thermosetting | Jacket, sheath, or armor |
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\*Where design conditions require maximum conductor temperatures above 90°C.
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#### 311.10(B) Thickness of Insulation and Jacket for Nonshielded Insulated Conductors.
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Thickness of insulation and jacket for nonshielded solid dielectric insulated conductors rated 2001 volts to 5000 volts shall comply with
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Thickness of insulation and jacket for nonshielded solid dielectric insulated conductors rated 2001 volts to 5000 volts shall comply with Table 311.10(B).
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Table 311.10(B).
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#### 311.10(C) Thickness of Insulation for Shielded Insulated Conductors.
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Thickness of insulation for shielded solid dielectric insulated conductors rated 2001 volts to 35,000 volts shall comply with Table
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311.10(C) and 311.10(C)(1) through (C)(3).
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##### 311.10(C)(1) 100 Percent Insulation Level.
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Cables shall be permitted to be applied where the system is provided with relay protection such that ground faults will be cleared as rapidly as possible but, in any case, within 1 minute. These cables are applicable to cable installations that are on grounded systems and shall be permitted to be used on other systems provided the above clearing requirements are met in completely de-energizing the faulted section.
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##### 311.10(C)(2) 133 Percent Insulation Level.
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Cables shall be permitted to be applied in situations where the clearing time requirements of the 100 percent level category cannot be met and the faulted section will be de-energized in a time not exceeding 1 hour. Cable shall be permitted to be used in 100 percent insulation level applications where the installation requires additional insulation.
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##### 311.10(C)(3) 173 Percent Insulation Level.
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Cables shall be permitted to be applied under all of the following conditions:
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* (1) In industrial establishments where the conditions of maintenance and supervision ensure only qualified persons service the installation
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* (2) Where the fault clearing time requirements of the 133 percent level category cannot be met
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* (3) Where an orderly shutdown is required to protect equipment and personnel
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* (4) Where the faulted section will be de-energized in an orderly shutdown
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Cables shall be permitted to be used in 100 percent or 133 percent insulation level applications where the installation requires additional insulation.
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Table 311.10(A) Conductor Application and Insulation Rated 2001 Volts and Higher
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Trade
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Name
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Type
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Letter
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Maximum Operating
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Temperature
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Application
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Provision Insulation
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Outer
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Covering
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Medium voltage solid dielectric
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MV-90 90°C Dry or wet locations Thermoplastic or thermosetting
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Jacket, sheath, or armor
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MV-105* 105°C
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*Where design conditions require maximum conductor temperatures above 90°C.
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Table 311.10(B) Thickness of Insulation and Jacket for Nonshielded Solid Dielectric Insulated Conductors
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##### Table 311.10(B) Thickness of Insulation and Jacket for Nonshielded Solid Dielectric Insulated Conductors
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Rated 2001 Volts to 5000 Volts
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@@ -217,9 +166,36 @@ Level mm mils mm mils mm mils mm mils mm mils mm mils
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1 7.11 280 8.76 345 11.30 445 — — — — — —
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1/0–2000 7.11 280 8.76 345 11.30 445 8.76 345 10.67 420 14.73 580
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### 311.12 Conductors.
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Table 311.10(C) Thickness of Insulation for Shielded Solid Dielectric Insulated Conductors Rated 2001 Vol
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#### 311.10(C) Thickness of Insulation for Shielded Insulated Conductors.
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Thickness of insulation for shielded solid dielectric insulated conductors rated 2001 volts to 35,000 volts shall comply with Table 311.10(C) and 311.10(C)(1) through (C)(3).
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##### 311.10(C)(1) 100 Percent Insulation Level.
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Cables shall be permitted to be applied where the system is provided with relay protection such that ground faults will be cleared as rapidly as possible but, in any case, within 1 minute. These cables are applicable to cable installations that are on grounded systems and shall be permitted to be used on other systems provided the above clearing requirements are met in completely de-energizing the faulted section.
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##### 311.10(C)(2) 133 Percent Insulation Level.
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Cables shall be permitted to be applied in situations where the clearing time requirements of the 100 percent level category cannot be met and the faulted section will be de-energized in a time not exceeding 1 hour. Cable shall be permitted to be used in 100 percent insulation level applications where the installation requires additional insulation.
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##### 311.10(C)(3) 173 Percent Insulation Level.
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Cables shall be permitted to be applied under all of the following conditions:
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* (1) In industrial establishments where the conditions of maintenance and supervision ensure only qualified persons service the installation
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* (2) Where the fault clearing time requirements of the 133 percent level category cannot be met
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* (3) Where an orderly shutdown is required to protect equipment and personnel
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* (4) Where the faulted section will be de-energized in an orderly shutdown
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Cables shall be permitted to be used in 100 percent or 133 percent insulation level applications where the installation requires additional insulation.
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##### Table 311.10(C) Thickness of Insulation for Shielded Solid Dielectric Insulated Conductors Rated 2001 Vol
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2001–
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5000
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@@ -290,23 +266,22 @@ Leve mm mils mm mils mm mils mm mils mm mils mm mils mm mils mm m
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2 2.29 90 2.92 115 3.56 140 4.45 175 4.45 175 5.59 220 6.60 260 — —
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1 2.29 90 2.92 115 3.56 140 4.45 175 4.45 175 5.59 220 6.60 260 6.60 2
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1/0–2000 2.29 90 2.92 115 3.56 140 4.45 175 4.45 175 5.59 220 6.60 260 6.60 2
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### 311.12 Conductors.
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#### 311.12(A) Minimum Size of Conductors.
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The minimum size of conductors shall be as shown in Table 311.12(A), except as permitted elsewhere in this Code.
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Table 311.12(A) Minimum Size of Conductors
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##### Table 311.12(A) Minimum Size of Conductors
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Conductor Voltage Rating (Volts)
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Minimum Conductor Size (AWG)
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Copper, Aluminum, or Copper-Clad Aluminum
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2001–5000 8
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5001–8000 6
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8001–15,000 2
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15,001–28,000 1
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28,001–35,000 1/0
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| Conductor Voltage Rating (Volts) | Minimum Conductor Size (AWG) Copper, Aluminum, or Copper-Clad Aluminum |
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| -------------------------------- | ---------------------------------------------------------------------- |
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| 2001–5000 | 8 |
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| 5001–8000 | 6 |
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| 8001–15,000 | 2 |
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| 15,001–28,000 | 1 |
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| 28,001–35,000 | 1/0 |
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#### 311.12(B) Conductor Material.
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@@ -386,8 +361,7 @@ Type MV cable shall be permitted for use on power systems rated up to and includ
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* (2) In raceways.
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* (3) In cable trays, where identified for the use, in accordance with 392.10, 392.20(B), (C), and (D), 392.22(C), 392.30(B)(1), 392.46,
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392.56, and 392.60. Type MV cable that has an overall metallic sheath or armor, complies with the requirements for Type MC cable, and is identified as “MV or MC” shall be permitted to be installed in cable trays in accordance with 392.10(B)(2).
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* (3) In cable trays, where identified for the use, in accordance with 392.10, 392.20(B), (C), and (D), 392.22(C), 392.30(B)(1), 392.46, 392.56, and 392.60. Type MV cable that has an overall metallic sheath or armor, complies with the requirements for Type MC cable, and is identified as “MV or MC” shall be permitted to be installed in cable trays in accordance with 392.10(B)(2).
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* (4) In messenger-supported wiring in accordance with Part II of Article 396.
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@@ -414,7 +388,8 @@ The metallic shield, sheath, or armor shall be connected to a grounding electrod
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> [!important] Exception No. 2:
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> Airfield lighting cable used in series circuits that are rated up to 5000 volts and are powered by regulators shall be permitted to be nonshielded.
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Informational Note to Exception No. 2: Federal Aviation Administration (FAA) Advisory Circulars (ACs) provide additional practices and methods for airport lighting.
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> [!info] Informational Note to Exception No. 2:
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> Federal Aviation Administration (FAA) Advisory Circulars (ACs) provide additional practices and methods for airport lighting.
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### 311.40 Support.
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@@ -422,44 +397,32 @@ Type MV cable terminated in equipment or installed in pull boxes or vaults shall
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### 311.44 Shielding.
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Nonshielded, ozone-resistant insulated conductors with a maximum phase-to-phase voltage of 5000 volts shall be permitted in Type
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Nonshielded, ozone-resistant insulated conductors with a maximum phase-to-phase voltage of 5000 volts shall be permitted in Type MC cables in industrial establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation. For other establishments, solid dielectric insulated conductors operated above 2000 volts in permanent installations shall have ozone-resistant insulation and shall be shielded. All metallic insulation shields shall be connected to a grounding electrode conductor, a grounding busbar, an equipment grounding conductor, or a grounding electrode.
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MC cables in industrial establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation. For other establishments, solid dielectric insulated conductors operated above 2000 volts in permanent installations shall have ozone-resistant insulation and shall be shielded. All metallic insulation shields shall be connected to a grounding electrode conductor, a grounding busbar, an equipment grounding conductor, or a grounding electrode.
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\[311.60(B)\]
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T =
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T =
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ΔT =
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R =
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Y =
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R =
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> [!info] Informational Note:
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> The primary purposes of shielding are to confine the voltage stresses to the insulation, dissipate insulation leakage current, drain off the capacitive charging current, and carry ground-fault current to facilitate operation of ground-fault protective devices in the event of an electrical cable fault.
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> [!important] Exception No. 1:
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> Nonshielded insulated conductors listed by a qualified testing laboratory shall be permitted for use up to 2400 volts under the following conditions:
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* (1) Conductors shall have insulation resistant to electric discharge and surface tracking, or the insulated conductor(s) shall be covered with a material resistant to ozone, electric discharge, and surface tracking.
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* (2) Where used in wet locations, the insulated conductor(s) shall have an overall nonmetallic jacket or a continuous metallic sheath.
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* (3) Insulation and jacket thicknesses shall be in accordance with Table 311.10(B).
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>
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> * (1) Conductors shall have insulation resistant to electric discharge and surface tracking, or the insulated conductor(s) shall be covered with a material resistant to ozone, electric discharge, and surface tracking.
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>
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> * (2) Where used in wet locations, the insulated conductor(s) shall have an overall nonmetallic jacket or a continuous metallic sheath.
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>
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> * (3) Insulation and jacket thicknesses shall be in accordance with Table 311.10(B).
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> [!important] Exception No. 2:
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> Nonshielded insulated conductors listed by a qualified testing laboratory shall be permitted for use up to 5000 volts to replace existing nonshielded conductors, on existing equipment in industrial establishments only, under the following conditions:
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* (1) Where the condition of maintenance and supervision ensures that only qualified personnel install and service the installation.
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* (2) Conductors shall have insulation resistant to electric discharge and surface tracking, or the insulated conductor(s) shall be covered with a material resistant to ozone, electric discharge, and surface tracking.
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* (3) Where used in wet locations, the insulated conductor(s) shall have an overall nonmetallic jacket or a continuous metallic sheath.
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* (4) Insulation and jacket thicknesses shall be in accordance with Table 311.10(B).
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>
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> * (1) Where the condition of maintenance and supervision ensures that only qualified personnel install and service the installation.
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>
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> * (2) Conductors shall have insulation resistant to electric discharge and surface tracking, or the insulated conductor(s) shall be covered with a material resistant to ozone, electric discharge, and surface tracking.
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>
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> * (3) Where used in wet locations, the insulated conductor(s) shall have an overall nonmetallic jacket or a continuous metallic sheath.
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>
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> * (4) Insulation and jacket thicknesses shall be in accordance with Table 311.10(B).
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> [!info] Informational Note:
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> Relocation or replacement of equipment may not comply with the term existing as related to this exception.
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@@ -491,7 +454,25 @@ Where more than one calculated or tabulated ampacity could apply for a given cir
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#### 311.60(B) Engineering Supervision.
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Under engineering supervision, conductor ampacities shall be permitted to be calculated by using the following general equation: where: conductor temperature (°C) ambient temperature (°C) dielectric loss temperature rise dc resistance of conductor at temperature, T component ac resistance resulting from skin effect and proximity effect effective thermal resistance between conductor and surrounding ambient c a d dc c c ca
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Under engineering supervision, conductor ampacities shall be permitted to be calculated by using the following general equation:
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### Equation 311.60(B)
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%% TODO %%
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T =
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T =
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ΔT =
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R =
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Y =
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R =
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where:
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conductor temperature (°C) ambient temperature (°C) dielectric loss temperature rise dc resistance of conductor at temperature, T component ac resistance resulting from skin effect and proximity effect effective thermal resistance between conductor and surrounding ambient c a d dc c c ca
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> [!info] Informational Note:
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> The dielectric loss temperature rise (ΔT ) is negligible for single circuit extruded dielectric cables rated below 46 kilovolts.
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@@ -500,20 +481,15 @@ Under engineering supervision, conductor ampacities shall be permitted to be cal
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Ampacities for conductors rated 2001 volts to 35,000 volts shall be as specified in Table 311.60(C)(67) through Table 311.60(C)(86).
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Ampacities for ambient temperatures other than those specified in the ampacity tables shall be corrected in accordance with 311.60(D)
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(4).
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Ampacities for ambient temperatures other than those specified in the ampacity tables shall be corrected in accordance with 311.60(D)(4).
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> [!info] Informational Note No. 1:
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> For ampacities calculated in accordance with 311.60(A), reference IEEE 835, Standard Power Cable
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Ampacity Tables, and the references therein for availability of all factors and constants.
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> For ampacities calculated in accordance with 311.60(A), reference IEEE 835, Standard Power Cable Ampacity Tables, and the references therein for availability of all factors and constants.
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> [!info] Informational Note No. 2:
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> Ampacities provided by this section do not take voltage drop into consideration. See 210.19(A), Informational
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> Ampacities provided by this section do not take voltage drop into consideration. See 210.19(A), Informational Note No. 4, for branch circuits and 215.2(A), Informational Note No. 2, for feeders.
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Note No. 4, for branch circuits and 215.2(A), Informational Note No. 2, for feeders.
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Table 311.60(C)(67) Ampacities of Insulated Single Copper Conductor Cables Triplexed in Air
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##### Table 311.60(C)(67) Ampacities of Insulated Single Copper Conductor Cables Triplexed in Air
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Conductor
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@@ -552,7 +528,7 @@ MV-105
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Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
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311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Table 311.60(C)(68) Ampacities of Insulated Single Aluminum Conductor Cables Triplexed in Air
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##### Table 311.60(C)(68) Ampacities of Insulated Single Aluminum Conductor Cables Triplexed in Air
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Conductor
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@@ -611,7 +587,7 @@ MV-105
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Note: Refer to 311.60(E) for basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
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311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Table 311.60(C)(69) Ampacities of Insulated Single Copper Conductor Isolated in Air
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##### Table 311.60(C)(69) Ampacities of Insulated Single Copper Conductor Isolated in Air
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Conductor
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@@ -663,7 +639,7 @@ Type MV-105
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Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
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311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Table 311.60(C)(70) Ampacities of Insulated Single Aluminum Conductor Isolated in Air
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##### Table 311.60(C)(70) Ampacities of Insulated Single Aluminum Conductor Isolated in Air
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Conductor
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@@ -712,12 +688,9 @@ Type MV-105
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1750 1215 1355 1195 1335 1165 1300
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2000 1320 1475 1295 1445 1265 1410
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Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
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311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and 311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Table 311.60(C)(71) Ampacities of an Insulated
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Three-Conductor Copper Cable Isolated in Air
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##### Table 311.60(C)(71) Ampacities of an Insulated Three-Conductor Copper Cable Isolated in Air
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Conductor
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@@ -776,9 +749,7 @@ MV-105
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Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
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311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Table 311.60(C)(72) Ampacities of an Insulated
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Three-Conductor Aluminum Cable Isolated in Air
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##### Table 311.60(C)(72) Ampacities of an Insulated Three-Conductor Aluminum Cable Isolated in Air
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Conductor
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@@ -817,9 +788,7 @@ MV-105
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Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
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311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Table 311.60(C)(73) Ampacities of an Insulated Triplexed or Three Single-Conductor Copper Cables in
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Isolated Conduit in Air
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##### Table 311.60(C)(73) Ampacities of an Insulated Triplexed or Three Single-Conductor Copper Cables in Isolated Conduit in Air
|
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Conductor
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@@ -878,9 +847,7 @@ MV-105
|
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Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
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311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
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Table 311.60(C)(74) Ampacities of an Insulated Triplexed or Three Single-Conductor Aluminum Cables in
|
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|
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Isolated Conduit in Air
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##### Table 311.60(C)(74) Ampacities of an Insulated Triplexed or Three Single-Conductor Aluminum Cables in Isolated Conduit in Air
|
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|
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Conductor Size (AWG or kcmil)
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|
||||
@@ -916,9 +883,7 @@ MV-105
|
||||
Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
|
||||
311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
|
||||
|
||||
Table 311.60(C)(75) Ampacities of an Insulated
|
||||
|
||||
Three-Conductor Copper Cable in Isolated Conduit in Air
|
||||
##### Table 311.60(C)(75) Ampacities of an Insulated Three-Conductor Copper Cable in Isolated Conduit in Air
|
||||
|
||||
Conductor Temperature Rating of Conductor
|
||||
|
||||
@@ -975,9 +940,7 @@ MV-105
|
||||
Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
|
||||
311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
|
||||
|
||||
Table 311.60(C)(76) Ampacities of an Insulated
|
||||
|
||||
Three-Conductor Aluminum Cable in Isolated Conduit in Air
|
||||
##### Table 311.60(C)(76) Ampacities of an Insulated Three-Conductor Aluminum Cable in Isolated Conduit in Air
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1013,13 +976,9 @@ MV-105
|
||||
750 430 480 470 520
|
||||
1000 505 560 550 615
|
||||
|
||||
Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and
|
||||
311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
|
||||
Note: Refer to 311.60(E) for the basis of ampacities, 311.10(A) for conductor maximum operating temperature and application, and 311.60(D)(4) for the ampacity correction factors where the ambient air temperature is other than 40°C (104°F).
|
||||
|
||||
Table 311.60(C)(77) Ampacities of Three Single-Insulated Copper Conductors in Underground Electrical
|
||||
|
||||
Ducts
|
||||
(Three Conductors per Electrical Duct)
|
||||
##### Table 311.60(C)(77) Ampacities of Three Single-Insulated Copper Conductors in Underground Electrical Ducts (Three Conductors per Electrical Duct)
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1113,10 +1072,7 @@ MV-105
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(78) Ampacities of Three Single-Insulated Aluminum Conductors in Underground
|
||||
|
||||
Electrical Ducts
|
||||
(Three Conductors per Electrical Duct)
|
||||
##### Table 311.60(C)(78) Ampacities of Three Single-Insulated Aluminum Conductors in Underground Electrical Ducts (Three Conductors per Electrical Duct)
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1210,8 +1166,7 @@ Detail 3.\]
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(79) Ampacities of Three Insulated Copper Conductors Cabled Within an Overall Covering
|
||||
(Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct)
|
||||
##### Table 311.60(C)(79) Ampacities of Three Insulated Copper Conductors Cabled Within an Overall Covering (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct)
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1323,10 +1278,7 @@ MV-105
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(80) Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall
|
||||
|
||||
Covering
|
||||
(Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct)
|
||||
##### Table 311.60(C)(80) Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall Covering (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct)
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1420,7 +1372,7 @@ Detail 3.\]
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(81) Ampacities of Single Insulated Copper Conductors Directly Buried in Earth
|
||||
##### Table 311.60(C)(81) Ampacities of Single Insulated Copper Conductors Directly Buried in Earth
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1494,7 +1446,7 @@ Two Circuits, Six Conductors \[See Figure
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(82) Ampacities of Single Insulated Aluminum Conductors Directly Buried in Earth
|
||||
##### Table 311.60(C)(82) Ampacities of Single Insulated Aluminum Conductors Directly Buried in Earth
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1568,8 +1520,7 @@ Two Circuits, Six Conductors \[See Figure
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(83) Ampacities of Three Insulated Copper Conductors Cabled Within an Overall Covering
|
||||
(Three-Conductor Cable), Directly Buried in Earth
|
||||
##### Table 311.60(C)(83) Ampacities of Three Insulated Copper Conductors Cabled Within an Overall Covering (Three-Conductor Cable), Directly Buried in Earth
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1649,10 +1600,7 @@ Detail 6.\]
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(84) Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall
|
||||
|
||||
Covering
|
||||
(Three-Conductor Cable), Directly Buried in Earth
|
||||
##### Table 311.60(C)(84) Ampacities of Three Insulated Aluminum Conductors Cabled Within an Overall Covering (Three-Conductor Cable), Directly Buried in Earth
|
||||
|
||||
Conductor Temperature Rating of Conductor
|
||||
|
||||
@@ -1730,9 +1678,7 @@ Detail 6.\]
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(85) Ampacities of Three Triplexed Single Insulated Copper Conductors Directly Buried in
|
||||
|
||||
Earth
|
||||
##### Table 311.60(C)(85) Ampacities of Three Triplexed Single Insulated Copper Conductors Directly Buried in Earth
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1805,9 +1751,7 @@ Two Circuits, Six Conductors \[See Figure
|
||||
|
||||
Note: Refer to 311.60(F) for basis of ampacities and Table 311.10(A) for the temperature rating of the conductor.
|
||||
|
||||
Table 311.60(C)(86) Ampacities of Three Triplexed Single Insulated Aluminum Conductors Directly
|
||||
|
||||
Buried in Earth
|
||||
##### Table 311.60(C)(86) Ampacities of Three Triplexed Single Insulated Aluminum Conductors Directly Buried in Earth
|
||||
|
||||
Conductor
|
||||
|
||||
@@ -1916,6 +1860,8 @@ Ampacities for ambient temperatures other than those specified in the ampacity t
|
||||
|
||||
###### Equation 311.60(D)(4)
|
||||
|
||||
%% TODO %%
|
||||
|
||||
I' =
|
||||
|
||||
I =
|
||||
@@ -1926,20 +1872,7 @@ T ' =
|
||||
|
||||
T = where: ampacity corrected for ambient temperature ampacity shown in the table for T and T temperature rating of conductor (°C) new ambient temperature (°C) ambient temperature used in the table (°C)
|
||||
|
||||
#### 311.60(E) Ampacity in Air.
|
||||
|
||||
Ampacities for conductors and cables in air shall be as specified in Table 311.60(C)(67) through Table 311.60(C)(76). Ampacities shall be based on the following:
|
||||
|
||||
* (1) Conductor temperatures of 90°C (194°F) and 105°C (221°F)
|
||||
|
||||
* (2) Ambient air temperature of 40°C (104°F)
|
||||
|
||||
> [!info] Informational Note:
|
||||
> See 311.60(D)(4) where the ambient air temperature is other than 40°C (104°F).
|
||||
|
||||
#### 311.60(F) Ampacity in Underground Electrical Ducts and Direct Buried in Earth.
|
||||
|
||||
Table 311.60(D)(4) Ambient Temperature Correction Factors
|
||||
###### Table 311.60(D)(4) Ambient Temperature Correction Factors
|
||||
|
||||
For ambient temperatures other than 40°C (104°F), multiply the allowable ampacities specified in the ampacity tables by the appropriate factor shown below.
|
||||
|
||||
@@ -1991,3 +1924,16 @@ Ampacities for conductors and cables in underground electrical ducts and direct
|
||||
|
||||
* (7) Maximum depth to the top of electrical duct banks shall be 750 mm (30 in.), and maximum depth to the top of direct-buried cables shall be 900 mm (36 in.).
|
||||
|
||||
#### 311.60(E) Ampacity in Air.
|
||||
|
||||
Ampacities for conductors and cables in air shall be as specified in Table 311.60(C)(67) through Table 311.60(C)(76). Ampacities shall be based on the following:
|
||||
|
||||
* (1) Conductor temperatures of 90°C (194°F) and 105°C (221°F)
|
||||
|
||||
* (2) Ambient air temperature of 40°C (104°F)
|
||||
|
||||
> [!info] Informational Note:
|
||||
> See 311.60(D)(4) where the ambient air temperature is other than 40°C (104°F).
|
||||
|
||||
#### 311.60(F) Ampacity in Underground Electrical Ducts and Direct Buried in Earth.
|
||||
|
||||
|
||||
Reference in New Issue
Block a user