Class 1 vs. Class2/3?

[olc]

What is the difference between a class 1 and a class 2 2 circuit?
A 24V transformer serving a simple emergency notification system (switch unlocks door and turns on light over the door). Is this class 1? Can a listed class 2 transformer be used for a class 1 circuit?

 

[kwired]

What is the difference between a class 1 and a class 2 2 circuit?
A 24V transformer serving a simple emergency notification system (switch unlocks door and turns on light over the door). Is this class 1? Can a listed class 2 transformer be used for a class 1 circuit?

Power limitations of the source are the main differences between class 1,2 and 3 control circuits. You can have two circuits that are different class, same voltage, depending on available power supply in some cases.

I think you can use class 2 supply for class 1 circuits, but you can not run class 1 wiring through a raceway and at other end convert wiring methods back to class 2 methods, the entire circuit must be class 1.

 

[hbiss]

The "class" of the circuit depends on the power source. So if you are using a class 2 transformer the circuit is class 2 and you can use wiring listed as CL2, CL3 or CM. If you want to use a class 1 wiring method for a class 2 circuit you certainly may since it exceeds the CL2 and CL3 requirements. But that's up to you.

-Hal