I think I know the calculation for this gang box, but I want to double check. Specifically, does the light count as a "yoke"? This is a 15A circuit.

Per my other question (Calculate electrical box volume needed) I see:

  • 3 14/2 coming into the box (count: 6)
  • 4 grounds (count: 1)
  • No clamps in the box

So that is 7 x 2in (14/2 awg) = 14.

But is the light a yoke? If so, that is +2 which means 9x2in for 18 needed.

I measured the round box and it is 4" by 2 1/4" (2 1/8" is all I could see in the nec tables) so that would allow for 21.5.


Sound about right? I am splicing in an outlet off this circuit and it would save me from putting up another gang box before the light.

light box

  • 1
    Most plastic boxes actually have the volume marked/molded into them. The NEC tables (That I know of) are for "standard" (never seen them marked) steel box sizes. Steel raised covers are usually marked as they are less standardized. There is some text in your box bottom but it's mostly hidden by the cable in the picture.
    – Ecnerwal
    Dec 8 '20 at 16:10
  • It sure does! 22.5.
    – Mike
    Dec 8 '20 at 16:43

Yes, the light fixture counts as a device/yoke.

The rest of your box-fill math looks correct.

  • Assuming yes, my other calculations worst correct right?
    – Mike
    Dec 8 '20 at 16:44

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