spectra05
Member
- Location
- Piedmont, NC
in section 334 of the nec code it lists type nm, nmc, and nms cable. nowhere in the section it talks about NM-b untill you get to 334.112 where it states that "the insulated power conductors shall be one of the types listed in Table 310.13 that are suitible for branch circuit wiring or one that is identified for use in these cables. Conductor rating shall be rated at 90 degrees C (194F)".
then says right under it FPN: types NM, NMC, and NMS cable identified by the markings NM-B, NMC-B, NMS-B. now for the purpose of de-rating type nm-b would i need to follow in accordance with 334.112 Conductor rating shall be rated at 90 degrees C (194F).
Or do i refer to 334.80 where it states that "the ampacity of types NM, NMC, NMS cable shall be determined in accordiance with 310.15. THe ampacity shall be in accordance with th 60 degree C conductor rating. The 90 degree C rating shall be used for derating purposes, provided the final de-rating ampacity does not exceed that for a 60degrees C conductor."
So if hypotheotically i had 1 14-2 type NM-B cable for a lighting circuit that passed through an attic above a range hood with an ambient temp of 42 degrees C. i would obviously de-rate 25A @ 90 degrees C. with a correction factor of .87 to get 21.75A. now would this be in compliance with 334.12. Or not in compliance with 334.80 in which i would need to at or less than 20A.
any help would be awesome thanx
then says right under it FPN: types NM, NMC, and NMS cable identified by the markings NM-B, NMC-B, NMS-B. now for the purpose of de-rating type nm-b would i need to follow in accordance with 334.112 Conductor rating shall be rated at 90 degrees C (194F).
Or do i refer to 334.80 where it states that "the ampacity of types NM, NMC, NMS cable shall be determined in accordiance with 310.15. THe ampacity shall be in accordance with th 60 degree C conductor rating. The 90 degree C rating shall be used for derating purposes, provided the final de-rating ampacity does not exceed that for a 60degrees C conductor."
So if hypotheotically i had 1 14-2 type NM-B cable for a lighting circuit that passed through an attic above a range hood with an ambient temp of 42 degrees C. i would obviously de-rate 25A @ 90 degrees C. with a correction factor of .87 to get 21.75A. now would this be in compliance with 334.12. Or not in compliance with 334.80 in which i would need to at or less than 20A.
any help would be awesome thanx