Voltage rating of AFCI control circuits in 1000V systems

[Carultch]

Does the control circuit wiring (24 Volts DC) of a system of 1000V AFCI combiners, also need to have a 1000V rating? It is routed in a separate raceway. And other than that approximate 1 foot of wire that is inside the combiner box, I see no reason why standard 600V wire isn't sufficient.

 

[GoldDigger]

AHJ might want to see a divider inside the box.
Outside that, I agree with you.

 

[pv_n00b]

If it's possible for the conductors to come into contact then they need the same voltage rating. In the case of the combiner it would need some type of protection to maintain conductor separation. You would think the manufacturer would have taken care of this.

 

[GoldDigger]

If it's possible for the conductors to come into contact then they need the same voltage rating. In the case of the combiner it would need some type of protection to maintain conductor separation. You would think the manufacturer would have taken care of this.

Running wires in the same raceway is subject to more restrictions (like same insulation voltage) than having the wires in the same box (with a divider if required.)

 

[pv_n00b]

The 2014 NEC 300.3(C)(1) is pretty specific about 1000V or less conductors in the same enclosure needing to be all rated the same as the maximum circuit voltage in the enclosure. There is no exception for installing barriers but AHJs seem pretty open about allowing them, particularly if they are part of the listed box. I think this is based on 314.28(D) which states that if a permanent barrier is used in a box then each section is considered a separate box.

If you are on the 2011 or earlier NEC then it's a no go to mix 1000V circuits with 600V or less circuits no matter what the insulation rating except in some very specific situations, see 300.3(C)(2). But again some AHJs allow the use of a barrier.