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I would like to know why pigtails are not included in the volume count for outlet receptacle boxes.

I recently upgraded to a two way outlet and had a total of four 14/2 wires coming into the box and stay under four wires per wire nut I used pigtails. This ended up leading to quite a few pigtails in the box but based on NEC codes I’ve seen people quote on here pigtails aren’t added to the count and I don’t understand why. It definitely can crowd the box!

Edit 1/8/2020 9:51pm: For example my situation is as follows: I’m looking at new handbook and maybe getting confused. I thought the point of this was to ensure there was enough space ( conductors to space ratio) for heat related issues. In my case , The outlet box is 38 cubic inches. I have 3 14/2 wires going in and 1 14/3 wire going in. I have two receptacle outlets for it. I wired the outlets in parallel instead of daisy chain (I created daisy chain to limit to a max of four wires in a wire nut). In total I have 6 black, 7 white , 1 red, and 7 ground. I had a total of 7 ideas protwist wire nuts used. So what does that put me at for total volume then?

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  • Since I am not an electrician I need a lot of this stuff spelled out for me too. This channel on youtube does a great job explaining most of the codes a homeowner needs to understand youtube.com/watch?v=SKwLgBVCDpk
    – redlude97
    Jan 8, 2021 at 18:51

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Using an NEC Handbook, which is the NEC with more information and comments, I find that the pigtails are currently counted as part of the device fill rather than a separate conductor. All of this can be found in Article 314.16 and the associated tables.

The NEC Handbook has a set of separate commentary tables. In particular, Table 314.3 shows how different device allowances change based on the number of conductors are attached to it.

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    It seems you were thinking, but not clicking. Your "included" tables aren't all that included... :D
    – FreeMan
    Jan 8, 2021 at 13:14
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    I think he might have been saying that he would include all the 314 tables in the handbook with this not that he was including them. The handbook I don’t believe is available for free as the code book is.
    – Ed Beal
    Jan 8, 2021 at 16:02
  • I’m looking at new handbook and maybe getting confused. I thought the point of this was to ensure there was enough space ( conductors to space ratio) for heat related issues. In my case , The outlet box is 38 cubic inches. I have 3 14/2 wires going in and 1 14/3 wire going in. I have two receptacle outlets for it. I wired the outlets in parallel instead of daisy chain (I created daisy chain to limit to a max of four wires in a wire nut). In total I have 6 black, 7 white , 1 red, and 7 ground. I had a total of 7 ideas protwist wire nuts used. So what does that put me at for total volume then?
    – Irish Redneck
    Jan 9, 2021 at 2:50
  • @IrishRedneck - I like your question but it might be better to put it into a question since the calculation would need more space and options than we have in comments. If you have noticed I purposely did not say which Year NEC I was talking about because each published year from 2011 - 2020 box fill calcs have changed. Also it would help to know which conduit cable/conductors (I am assuming NM) and the box type and physical size we are talking about. So if you want to post it up as a question I can run through the calcs in detail.
    – Retired Master Electrician
    Jan 10, 2021 at 20:31
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Explanations of this to make it simple is the largest size wire connecting to the device 14 awg 2x2 , or 12 awg 2.25x2 the device size did not change but the associated wire size did get larger may be a way to say it that is easier to understand. The device requires a 2x multiplier of the wire size that size is listed in 314.16.B. So the device being the same the only thing that changes is the wire size and this accounts for that.

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