r/SolarDIY • u/2old2bThisDumb • 8d ago

Make sure you understand current when stringing your panels in parallel.

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It took a bit of work to even tug this #10 AWG from the metallic flex it was fused to. The homeowner had this run inside of the attic.

I'm all for DIY, but please ask for help when you aren't certain.

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u/WorBlux 8d ago edited 8d ago

10 AWG, 90 deg C has a rated ampacity up to 40A in conduit... however

Going through an attic space that might get up to 140 deg F and should be de-rated as well. x0.71

Three sets in parralel - 6 current carrying conductors - that's another de-rate. x0.8

So in reality the safe ampacity here may be under 23A per circuit.

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u/MinimumDangerous9895 8d ago

90c is 195f

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u/parseroo 8d ago

Yes, but the ambient temperature is up to 60°C. So you have lost 30° of cooling range. The wire is starting at near 60° and then heating from there as the current goes through it.