Re: dc current conductors
dc -
Originally posted by dcdave:
How many #10awg use-2 dc positive conductors can share a 1-1/4" emt conduit in a solar photovoltaic roof mount system?
Unless I'm missing something, this is a pretty standard conduit fill calc. I don't have a mfg cat handy, so don't have an accurate dimension for #10 USE
So, assuming stranded, using the conductor dim from CH 9, Table 8 and the insulation thickness from Table 310.13, the diameter is about .196 in. That puts the area at .029 in^2.
Per Ch 9, table 4, 1-1/4" EMT, at 40% fill, available cross sectional area is .589 in^2.
So you can pull 20 conductors and be below 40% fill.
Originally posted by dcdave:
Does the 9 cunductor rule apply or can more be allowed because its dc electricity?
Art 690.8 says to size conductors for 125%. So the NEC thinks the conductors could be under continuous load and get hot. And, DC current heats the wires just as well as AC. No reason why Table 310.15(B)(2)(a) wouldn't apply.
I did not see anything in Art. 690 that would give special forgiveness.
My response is pretty simplistic. Makes me think there may be more to your questions.
carl
[ January 09, 2005, 11:12 AM: Message edited by: coulter ]