Wiring pertaining to Variable Air Volume(VAV) diffusers

[riverjig87]

First, If this has question has been addressed, I apologize. I tried searching this forum with as many derivatives of terminoly that I could think of in order to get close, but no cigar.

My question is an easy one but Im having difficulty getting a defined answer.

In VAV control cabinets, it has some controls utilizing various sizes of wires for the controls and circuitry. When entering this cabinet with 120 volt power for the transformer inside, is this a violation?

That was the question asked by another journeyman and I had only one answer in mind. It should be allowable as long as all wiring inside this cabinet is rated for the same volatges(in this case 600v). We have disconnects which comprise of 20 amp snap switches located approx. 2 feet from each VAV. Also, these cabinets even include removable knock outrs for conduit in order to enter. I feel my answer is the most common, if in fact I am correct in my thinking.

Am I correct in my understanding of this application? I know there has got to be more codes which address this and I would appreciate any extra " ammo" I can get. I have a feeling the inspector is going to question this installation and would like to be prepared with more concrete answers.

Thank you.

 

[iwire]

Check out 725.55 in particular 725.55(D)(1).

The conductors can share the enclosure as long as they are routed so that at least 1/4" of separation is maintained between the class 1 and the class 2 or 3 conductors.

 

[infinity]

I agree with Bob and would add that what the manufacturer does with their equipment would be outside of the scope of the NEC. The installer should only be concerned with field wiring the units as per the manufacturer's instructions (i.e. using the provided KO's). The is no need to go beyond that with a piece of listed equipment.