Cable Fill and Pigtails in boxes
Maybe a dumb question…..but do the wires for pigtails need to be counted as extra cables when calculating box fill, or are they considered merely an extension of the conductors already coming in the box?
Let’s say I have a box with a cable fill max of 9. I have three romex cables coming into the box (total of 9 conductors, counting grounds). If I wirenut the blacks in one bundle, whites in another and grounds in a third, each with a pigtail going to a single outlet fixture, is this still 9 conductors, or have I bumped it up to 12 with the pigtails?
–Ken
Replies
Not a dumb question.
It is shown in the "illustrated guides" published to help understand the NEC.
Only the wires entering or exiting the box are counted.
"A conductor running through the box shall be counted as one conductor" So if the conductor makes no connection in the box it counts as one.
"Conductors, no part of which leaves the box, shall not be counted."
So, pigtails add zero.
This was quoted from a 1981 NEC as it was handy, but I do not think it has changed.
BTW, there is an error in your example, the grounds, all three, count as one.
"..deduction of one conductor shall be made for one or more grounding conductors entering the box."
So, in your three ?/2 NM-B entering a box with a receptacle the count will be:
one for ground wires
three for whote wires
three for black wires
two for the receptacle
Total of nine (9) for conductor count. This is assuming no internal clamps to hold the romex.
Internal clamps, hickeys or studs also count one.
Hey wait, this 1981 NEC says only count one for each strap mounted device. Well, that has changed! Let's check the 2002 NEC. Yep, it is a count of two for each strap. 314.16.b.4 2002
Frank DuVal
You can never make something foolproof because fools are so ingenious.
Thanks! Where in the code were you quoting from for the conductors in the box? I'd like to look that one up in the new 2005 code....
--Ken
Edited 2/27/2006 2:05 am by Globaldiver
in the 1999 NEC, it's 370-16.
I do not have a 2005 code, just keep up with Mike Holt's web site and ECM magazine for now.
2002 code is section 314. A lot of section number changes from 1999 to 2002. It was 370 in 1999.I was quoting the 1981 code book, but it is also found in the 2002 section 314.16.B.1 Conductor Fill.Frank DuVal You can never make something foolproof because fools are so ingenious.