Latest Discussions : Electrical & Lighting

edight

12:25PM | 01/08/03
Member Since: 01/05/03
5 lifetime posts
I'm having trouble understanding a section of the NEC. It's the part that states that non-metallic cables bundled together for more than 24" need to be downrated. I don't want to downrate the cables but I also I want to drill the minimum number of holes in my studs that is necessary for running several cables in a wall. Does anyone know how far apart the cables need to be before they're not considered bundled? I would like to run three cables through each hole and then somehow separate them the required distance between studs.

Thanks in advance!
-eric

Tom O

11:27AM | 01/09/03
Member Since: 09/17/02
476 lifetime posts
You will not have to worry about derating 3 cables if they are bundled, provided that you are dealing with single phase power (what almost all homes have).

Three each two wire cables results in 6 current carrying conductors and their ampacity is still 20 amps or more.

Three each 3 wire cables, run as multi-wire circuits still only have 6 current carrying conductors You don't count the neutrals in this case, but even if you did, the final ampacity is still 20 amps or more.

None of this takes temperature into account.

Tom

edight

08:00AM | 01/10/03
Member Since: 01/05/03
5 lifetime posts
Ah, I see now. I'm slowly figuring this out. Thanks for all the info, Tom. I'll keep in mind that I still need to consider temp and voltage drop.

So it looks like I'll be able to bundle four cables (8 current carrying conductors) together and still be above the max ampacities for 14AWG and 12AWG (what I'm using). But I'll still have 2 bundles of four that will need to run parallel for more than 2 feet. How far apart should these two bundles be?



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