Req'd to replace small outlet boxes when upgrading wiring in an olderhome?

I'm upgrading wiring in an older home which originally had ungrounded two-wire fabric-sheathed cable. I replaced it with 12/2 with grounding wire in a few circuits.
The existing handy boxes (is that the right word for outlet boxes?) are not as big as the ones currently being sold.
For a middle of the run receptacle, I'm looking at 4 wires + ground + grounding wire nut (the one with the pass through if you've seen them) and clamps in one of those boxes which is 12 cu in or less, and I can barely close up the outlet cover.
I'm wondering, is it required to change the outlet boxes to the bigger 14 cu in (or bigger) boxes when I upgrade the wiring? That would be much more work than I had originally anticipated.
Thanks.
-- Himanshu
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Greetings,
The NEC requires that you allocate 2.25 in^3 for each 12 awg wire entering the box. No matter how many grounds enter the box you only count 1 ground. Your receptacle counts as 2 wires. Add it all together and I come out with
2.25 hot going to the receptacle 2.25 neutral going to the receptacle 2.25 hot going from the receptacle 2.25 neutral going from the receptacle 2.25 grounds 5.5 receptacle =======================================15.75 in^3 2.25 cable clamps inside box =======================================18.00 in ^3
If you do upgrade the boxes 14 in^3 would be a violation of the NEC. If you don't upgrade the boxes your inspector will likely allow them to be grandfathered in but they won't have enough room to hold the wires without cramming. If you do decide to cram try to avoid pigtails and wire nuts. Make each wire exactly 6" long. In some tight boxes I have done away with the wire nut for the ground to save room. Allow one ground wire to loop 3/4ths of the way around the ground screw attached to the metal box and then continue on. Allow the other ground wire to wrap around the ground screw of the self-grounding receptacle and continue on. Next twist the ground wires together tightly for about 1" but do not put a wire nut on. I only bring this up for the exceptionally tight box.
Hope this helps, William
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I believe you could also just put in a GFI outlet or circuit breaker to give you protection from the ungrounded wiring. That's what happened in my house. I had some circuits on ungrounded 12 and 14 gauge Romex and it was too much of a pain to re-run it, so when I had my service panel changed to 200 Amps, we put in GFI circuit breakers. It is allowed under code.
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I believe you're off on your receptacle calc. It should be 4.5 shouldn't it? Either way, it's a bit irrelevant since his current boxes are not near the 17 in needed.

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Greetings,
Important: My original total, 18 in^3, is correct. 17 in^3 is too small. Yes, the 5.5 is a typo and should be 4.5.
Sorry for any confusion, William
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On Sun, 07 Aug 2005 04:39:33 GMT, Himanshu

Short answer is yes. For 12ga, 5 wires and a receptacle you need a 16 cu/in box.
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Himanshu wrote:

<snip>

Thank you all for your suggestions.
The local inspector said that for the end-of-the-run, I could keep the older box, but for middle-of-the-run, I would have to install a bigger box during the upgrade.
--
Himanshu


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