Shallow 3/0 metal “pancake” box fill

[crtemp]

I have a round metal shallow box that I have used for years. Just noticed it says 4 cubic inches on it. How are these legal when a 14-2 with clamp would calculate to 8 cubic inches?

 

[infinity]

14/2 AC cable with the connector on the outside of the box.

 

[crtemp]

14/2 AC cable with the connector on the outside of the box.

So if it’s amored cable, emt, fmc, or the like, no ground is counted in the Calc as long as the connector is external? Either way for my installation I’m using NM-B.

 

[raider1]

Keep in mind that if you are using a luminaire that has a canopy with a marked fill in cubic inches you can use that for additional conductor fill. See 314.16(A).

Chris

 

[crtemp]

Keep in mind that if you are using a luminaire that has a canopy with a marked fill in cubic inches you can use that for additional conductor fill. See 314.16(A).

Chris

Would it have to be stamped in the canopy? I’ve never seen it on any of the lights.

 

[Dennis Alwon]

Would it have to be stamped in the canopy? I’ve never seen it on any of the lights.

Yes, it must be stamped on the fixture and I agree I have never seen one that was marked

 

[JFletcher]

Keep in mind that if you are using a luminaire that has a canopy with a marked fill in cubic inches you can use that for additional conductor fill. See 314.16(A).

Chris

Close; see 314.16(B)(1) exception.

 

[ActionDave]

Yes, it must be stamped on the fixture..

Where does it say that in the code?

 

[infinity]

Where does it say that in the code?

314.16(A) says this:

314.16(A) Box Volume Calculations. The volume of a wiring enclosure (box) shall be the total volume of the assembled sections and, where used, the space provided by plaster rings, domed covers, extension rings, and so forth, that are marked with their volume or are made from boxes the dimensions of which are listed in Table 314.16(A).

But then 314.16(B)(1)Exception throws this at you:

314.16(B)(1)Exception: An equipment grounding conductor or conductors or not over four fixture wires smaller than 14 AWG, or both, shall be permitted to be omitted from the calculations where they enter a box from a domed luminaire or similar canopy and terminate within that box.

 

[raider1]

Close; see 314.16(B)(1) exception.

314.16(B)(1) Exception allows you to omit fixture wires smaller than #14 from being counted if the originate in a canopy.

314.16(A) Allows you to use a marked luminarie Canopy with a cubic inch capacity in the box fill calculation.

Chris

 

[Sierrasparky]

I've seen people have 2 14-2 in one 3/0 pancake box on the plywood exterior of homes all the time.

I don't I guess I waste the time to install a proper box. :rant: