Electrical Box Fill - Does it apply to Cabinets?

[Designer69]

Just wondering if the electrical box fill calculations, meant for outlet boxes, also apply to equipment cabinets too?

 

[augie47]

Cabinets are covered by Art 312, Boxes by Art 314.
312.6-312.9 address conductors.

 

[Designer69]

312.6(A) seems to say that a wiring duct shall be installed for wiring inside an electrical cabinet.

Do I understand that right? Meaning you can't just have loose or wiring routed within with just plastic ties.


As far as spacing requirements, it just says make sure there's adequate space.

 

[hbiss]

Equipment cabinet, electrical cabinet? I have to assume you are not talking about a splice box but a cabinet that primarily functions to contain components such as a control panel or even a breaker panel. The introduction of external wiring is incidental. As far as I know the NEC doesn't have anything to say about wire fill in such cases. The design would be up to UL, assuming that the panel is going to be listed.

-Hal

 

[kwired]

Art 100 definitions:

Cabinet.
An enclosure that is designed for either surface mounting or flush mounting and is provided with a frame, mat, or trim in which a swinging door or doors are or can be hung.

 

[kwired]

312.6(A) seems to say that a wiring duct shall be installed for wiring inside an electrical cabinet.

Do I understand that right? Meaning you can't just have loose or wiring routed within with just plastic ties.


As far as spacing requirements, it just says make sure there's adequate space.

A wiring space associated with devices installed in a cabinet can be space inside same cabinet or an adjacent wiring gutter external to the cabinet.

If you needed x number of inches of space to land conductors on a breaker and that space exists between the breaker and wall of the cabinet - then you are good, if you don't have that space but enter the cabinet opposite the breaker terminals from an external gutter with the required space, then you are still good. This usually not something you need to think much about with ~100 amps or less of conductor ampacity.

 

[don_resqcapt19]

Cabinets are covered by Art 312, Boxes by Art 314.
312.6-312.9 address conductors.

However the most common "junction box" that I use is covered by Article 312. Junction boxes that have covers that "telescope" over the box are listed as "cutout boxes" and covered by Article 312 per the scope. Since the scope of 314 applies to all boxes used as junction boxes, both articles apply to "cutout boxes".

 

[augie47]

I based my answer on:
314.1 Scope. This article covers the installation and use of all boxes and conduit bodies used as outlet, device, junction, or pull boxes, depending on their use, and handhole enclosures.
Cast metal, sheet metal, nonmetallic, and other boxes such as FS, FD, and larger boxes are not classified as conduit bodies.
This article also includes installation requirements for fittings used to join raceways and to connect raceways and cables to
boxes and conduit bodies.