tilden
Member
- Location
- Chapel Hill, NC, USA
I have a scenario where I will be running a number of conductors from an electrical room, up through the building, penetrating the roof, and then over a roof for a while. I'm hoping to only have one penetration and will have 12 CCC's running through the single conduit within the building. On the roof, the conductors will be going multiple directions in many separate conduits, splitting off in a junction box only a few feet away from the penetration.
I know I need to use the temperature adder for exposed conduit on a roof for my temperature derate, and that I'll need to use a 50% derate for having 12 conductors in the same conduit inside, but I'm trying to determine if I can justify not needing to use both the 50% conduit fill derate and temperature derate at the same time for all the conductors. Basically - can I use the temperature adder only for the conductors on the roof because they will be in separate conduits and no fill factors will apply, and then do a separate calculation for the conductors in the building with the fill factor applied but no temperature adder because the length of conduit on the roof with all the conductors in it is less than 10', then just take the result of the two separate calculations that leads me to needing the larger wire size as my result?
Is it ok to make these two calculations separately with the conductors being continuous, or if I had some sort of a splice in the junction box where the conductors all separate so that technically the conductor going through the building is different from the conductor on the roof would that make it ok?
I hope I've described this well enough to understand, but please ask for more details if I haven't.
I know I need to use the temperature adder for exposed conduit on a roof for my temperature derate, and that I'll need to use a 50% derate for having 12 conductors in the same conduit inside, but I'm trying to determine if I can justify not needing to use both the 50% conduit fill derate and temperature derate at the same time for all the conductors. Basically - can I use the temperature adder only for the conductors on the roof because they will be in separate conduits and no fill factors will apply, and then do a separate calculation for the conductors in the building with the fill factor applied but no temperature adder because the length of conduit on the roof with all the conductors in it is less than 10', then just take the result of the two separate calculations that leads me to needing the larger wire size as my result?
Is it ok to make these two calculations separately with the conductors being continuous, or if I had some sort of a splice in the junction box where the conductors all separate so that technically the conductor going through the building is different from the conductor on the roof would that make it ok?
I hope I've described this well enough to understand, but please ask for more details if I haven't.