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Posted by James \"Cubby\" Culbertson on August 7, 2005, 9:21 am
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.
> 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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