Understanding Art 725 Circuits and wiring types

tom baker

First Chief Moderator
Staff member
I made this chart for my classes on "low voltage", it explains the three types of circuits in Art 725, and the type of wiring allowed.
Class 1 is wired with a chapter 3 wiring method
Class 2 is the most common type of low voltage, IE thermostats
Class 3 is for equipment with higher power requirements.

The biggest misconception is you can insulate all the conductor to the same voltage rating (300.3(C)) and mix power and low voltage in the same raceway, but most miss the note which sends you to Art 725 and there is says you can't.

PM me if you see an correction needed.