Section 310.15(B)(20(a) requires derating of more than 3 current carrying conductors in a cable or raceway. Section 240.4(B) allows the next higher standard overcurrent device rating above the ampacity of the conductors being protected to be used. Does that mean I can bundle 40 14/2 NM cables together for long distances, and connect each to a 15 amp cb? 80 current carrying conductors would require a 35% derating from 25 amps to 8.75 amps. Can I then bump the cb up to 15 amps because Section 240.6 gives me the lowest standard rated breaker as 15 amps? Or, am I required to use a 10 amp fuse?
I'm giving you guys a red sticker. Wording in the code is the "next higher standard overcurrent device" Not the next size circuit breaker. 10a. is the next size overcurrent device for earlydean's post. Guess someone is installing fuses on these circuits.
#97800 - 03/21/0607:27 PMRe: even more derating fun
I think that sticker should be pink instead of red, thereby giving partial credit. After all, Iwire did point out that going up to the next OCPD does not allow you to increase the ampacity (or load) of the conductors and he did correctly make the call about multioutlet circuits. These points seem to be lost on many, at least here in the Mountain State.
Few things are harder to put up with than the annoyance of a good example.
#97801 - 03/21/0607:44 PMRe: even more derating fun