Stretch56
New member
- Location
- California
I've run into this problem more than once. I'm installing a new Subpanel to an attached garage and the derating issue for NM in conduit keeps popping up. I have a 2" PVC sleeve that's 36" long and hits a LB as it goes into the attic. It has a slip joint on the attic side for abrasion and I do seal it. I have a 6-3 run from the main panel and will have several 12-2 runs from the attic feeding through the same riser. I don't want to derate if possible.
Depending on which inspector I get, determines whether or not it gets Red Tagged. There have been conflicting statements about conduit runs and derating the cable but the consensus is the 24" limitation requirement is for a complete raceway and does not apply to a conduit sleeve which just protects the cable from damage. 312.5(C)says the sleeve can be between 18" and 10'. Where I run into problems is:
(g) Where installed as conduit or tubing, the allowable
cable fill does not exceed that permitted for complete conduit
or tubing systems by Table 1 of Chapter 9 of this Code
and all applicable notes thereto.
If the length is a problem, would installing a junction box midway down the sleeve break the 24" derate distance limitation? I could use the box as a pull through and bring branch circuits it from there.
Thanks in advance
Depending on which inspector I get, determines whether or not it gets Red Tagged. There have been conflicting statements about conduit runs and derating the cable but the consensus is the 24" limitation requirement is for a complete raceway and does not apply to a conduit sleeve which just protects the cable from damage. 312.5(C)says the sleeve can be between 18" and 10'. Where I run into problems is:
(g) Where installed as conduit or tubing, the allowable
cable fill does not exceed that permitted for complete conduit
or tubing systems by Table 1 of Chapter 9 of this Code
and all applicable notes thereto.
If the length is a problem, would installing a junction box midway down the sleeve break the 24" derate distance limitation? I could use the box as a pull through and bring branch circuits it from there.
Thanks in advance