---
id:
aliases: []
tags:
  - occupational/systems/subfeeds
  - type/guide
---
# Subfeeds

## Sequence

### 1. Preparation

1. Read about the project specifications and construction type
  * Delivery Method: (Plans & Specs, Design Build, Design Assist, Preliminary Budget)
  * Deck Thickness
  * Corridor Ceiling type

2. In the drawings, locate:
  * Unit Panel Schedules
  * Unit Load Calculations
  * Riser Diagram
  * Subfeed schedule (if present)

### 2. Takeoff

1. Determine wiring method

    | Construction Type | Wiring Method | Subfeed Options |
    | ----------------- | ------------- | --------------- |
    | 1,2 | MC Cable | MC, PVC, EMT |
    | 3,4,5 | NM Cable | SER, EMT |

    %%
    TODO: Create flow chart for wiring methods.
    Some cases to mention:
    * Deck thickness (minimum 3x conduit outer diameter)
    * Renovations (may not be able to run in slab)
    %%

2. Route subfeeds to the Meter Centers using appropriate adder lengths
   Add an additional 10ft for makeup when using MC cable.

    > [!tip]
    > Identify if and where typicals can be used

3. Assign material to lengths and apply Voltage drop if applicable

4. Pigtail Adaptors and Wireway Troughs if applicable

#### Pigtail Adaptors

![[burndy-AYP300_pigtail-adaptor.png]]

Pigtail adaptors are used where feeder wires exceed the range of panel lugs.

| Load Center Size | Max Feeder Size |
| ---------------- | --------------- |
| 100A             | 2/0 AWG         |
| 125A             | 3/0 AWG         |
| 150A             | 4/0 AWG         |
| 225A             | 300 kcmil       |
| 400A             | 500 kcmil       |

`ITEM DATABASE`/`WIRE & CABLE ACCESSORIES`/`WIRE LUGS & SPLICING`/`PIGTAIL ADAPTORS...`/`ADAPTOR STRAIGHT PIGTAIL - ...`

> [!info]
> "Pigtail adaptor" is the most common name and spelling for the device,
> however it's something of a misnomer, having nothing to do with pigtails
> (a short length of wire),
> the name likely stemming from the device being used in lieu of a pigtail.

#### Meter Center Troughs

Only for PVC subfeeds where we own voltage drop.

* `Area` = "Typical - Building Levels With Meter Centers"
* `System` = "Electrical"
* `Phase` = "Sub Feeders"

`ITEM DATABASE`/`DISTRIBUTION`/`BUDGET ITEMS $ & LBR`/`METER CENTER WIRE TROUGH ($400/E)`

### 3. Review

1. Use the extension tab to determine the Correct Quantity