Good books for specific topics

[MiElectrician]

I'm going through "interpreting the nec" and like it but it doesn't spend much time on some subjects. I was wondering if anyone had recommendations for books on specific things, like class 1,2, and 3 circuits or calculating load (still don't understand how to calculate a neutral).

Any advice is appreciated

 

[mgookin]

A quick search turns up:

http://ecmweb.com/code-basics/classifying-and-using-class-1-2-and-3-circuits

http://lmgtfy.com/?q=class+1,2,+and+3+circuits