One of the most difficult things to do with the NEC, is to understand how to use it to properly size wires. You can get 10 of the top experts in the world in a room and if you talk about how to properly size a wire, you can be sure there will be exciting conversations (disagreements). The best article I ever read on the subject was in the now retired SolarPro Magazine, where you can still access old articles at www.solarprofessional.com. May SolarPro someday be resurrected!

 

Wire sizing is very uniform throughout the NEC, so if you truly understand this article, you will be able to wire size about anything, including an energy storage system or a circuit to an air conditioner on the roof.

 

As I read this article that is based on the 2011 NEC, I make comments and update how to comply with the 2020 NEC. A few differences are that we no longer have 1A fuse increments below 15A (we skip from 10A to 15A now) and we no longer derate for conduit in sunlight on a rooftop.

 

Warning: This information is difficult, so do not expect to understand it in a day. You are welcome to skip this podcast, or you can do what I did when I first read NEC Article 690. I did not understand it, but got familiar with it and the terminology and after reading it 1000 times or so, I wrote some books on it.

 

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