cm cable

[seattle]

I am having a contractor rough in some wiring for some process controls. They are using cm cable for powering some control loads at 24vac. There are other loads of 120 vac. All these loads are in the 5-15 va range. I have been told that they can wire these loads with the same type cm cable. I understand the code ref requiring cm class 2 or 3 not to have a voltage rating marked on it. I also understand that dual purpose cm cable may be marked for the voltage,(300v) in this case. Is the 120 volt circuit a cm circuit or a class 1 circuit? Is the cm approved for a class 1 circuit in this case (if it is fused properly)?

not sure...

 

[hbiss]

Re: cm cable

If the voltage is 120 volts I very strongly doubt that this would be anything but a class 1 circuit. If the 120 volt circuits originate from a controller the manufacturer should offer guidance or labeling as to the required wiring. If this is simply a switched circuit (dry or wet contacts in the conroller) then this is most certainly a class 1 circuit and must use chapter 3 wiring methods.

Cable that is listed "CM" is communications multipurpose. Along with CM you will have CL2 or CL3. CL2 is rated at 150 volts, CL3 at 300. This doesn't mean though that you can put 120 volts on them in most cases.

-Hal