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alkizmo
join:2007-06-25
Pierrefonds, QC

4 edits

1 recommendation

alkizmo to whizkid3

Member

to whizkid3

Re: NMWU cable protection for direct burial - Suggestions?

said by whizkid3:

As well, being in a wet environment, also likely rules out using the 90C ampacity. Use the 75C column in your code book. If you have to de-rate the wires in your calculations, you can start with the 90C ampacity. It the end result is greater than or equal to the 75C ampacity, then you are fine. You still can not run more than the amps at 75C through the wire.

Well the RW90 gauge rating I picked was from the chart for raceways.

A confirming chart is the RW75 free air chart showing 12 gauge allowed up to 25 amps.

Here's the charts I should be looking at



So, 12 gauge with 3 conductors in raceway = 20amps
I'd have 4 conductors (2x neutral 2x hot, ground doesn't count and even if it did, I'd fall within the same 0.80 factor.)

20 amps x 0.8 factor = 16 amps.

So I'd be fine.