DC photovoltaic positive and negative in separate raceways

[ggunn]

I attached a picture to show what I am questioning. As you can see thirteen modules are across with negative on one side and positive on the other.

I still don't see why you want to do this. If you run the + home runs under the array back to where the - home runs tie in, the wire length is the same and you avoid this issue altogether.

 

[jaggedben]

But what about when you are in the vicinity of the array? Is there wording saying conductors do not have to be grouped then? Clearly they have to split somewhere but is there wording allowing that?

690.31(B) permits single-conductor cable within the array, but not elsewhere, and only requires it to be in an raceway if readily accessible. So that's pretty close to what you're asking.

300.3(B) covers all kinds of raceways, enclosures, trenches, etc,. If you're not on the array you're pretty much required to be in one of those things to have an NEC compliant wiring method.

So pretty much there you go.

 

[Carultch]

I still don't see why you want to do this. If you run the + home runs under the array back to where the - home runs tie in, the wire length is the same and you avoid this issue altogether.

One reason you might want to do this, is if you have source circuits that stretch across the width of a roof, and you believe that it is mechanically easier to have all the positives penetrate the roof on the left, and all the negatives penetrate the roof on the right. And then route both raceways to where the inverters are. This avoids source circuit wiring needing to go all the way across the roof, however as discussed, it is not something that you should do in practice. Questionably a violation, and the issue of magnetizing conduits.

Another case I saw in practice is where I sped'd a 1 1/4" conduit for all circuits to run complete from the transition enclosure to the inverter. Because the contractor didn't use 1 1/4" on the job, the contractor installed 2/ 1" conduits instead. Put positives in one and negatives in the other. And it was 3 source circuits, so it is pretty difficult to divide that in half for reworking.

 

[iwire]

But what about when you are in the vicinity of the array? Is there wording saying conductors do not have to be grouped then? Clearly they have to split somewhere but is there wording allowing that?

It allows single conductor cables it does not say they do not have to be grouped