JFletcher
Senior Member
- Location
- Williamsburg, VA
I don't have my copy of the NEC nearby, but I need to know how to calculate box fill. From memory, each 14ga wire counts as 2cu in, each 12 as 2.25, all grounds count as 1, each 1 gang device as 2, internal clamps as 1, wire nuts and jumpers/pigtails are not counted. Is this basically correct?
For a 22 cu in j-box, would my max # of 14 awg cables (14/2 w/ ground NM) be 5?
5 hot, 5 neutral, for 10 wires x 2 cu in each, plus 1 for the grounds = 21cu in?
If it were 18cu in, then would that limit me to 4 14/2 cables? 8 conductors x 2 = 16 + 1 for grounds = 17.
I think this is right but I've seen plenty of 18 cu in boxes with 4 12/2 and a receptacle, so I'm not sure I'm doing the math right re: conductor counts.
If there is a good weblink for box calculations, tia for providing it.
For a 22 cu in j-box, would my max # of 14 awg cables (14/2 w/ ground NM) be 5?
5 hot, 5 neutral, for 10 wires x 2 cu in each, plus 1 for the grounds = 21cu in?
If it were 18cu in, then would that limit me to 4 14/2 cables? 8 conductors x 2 = 16 + 1 for grounds = 17.
I think this is right but I've seen plenty of 18 cu in boxes with 4 12/2 and a receptacle, so I'm not sure I'm doing the math right re: conductor counts.
If there is a good weblink for box calculations, tia for providing it.