From PV to DC disconnect

[extrafu]

Hello,

I'm finalizing my PV installation in the next 2 weeks and I would like to have recommendations on wiring the PV to the DC disconnect box.

Quick system summary: 24 panels, CS 280W. 2 ground mounts of 12 panels each. All panels wired in series on each ground mount. Two strings of about 10 amps at 400-450V will go to a single Square D H361 DC disconnect box. Then, into 2 Conext MPPT 600-80 CCs. All of this was validated by Schneider directly.

The ground mounts are about 50 - 75 feet away from the mechanical room that has all the gear. I can't burry a cable too deep, perhaps 2 feet at the most before hitting bedrock.

Since I can't burry them too deep, I was considering using Schedule 40 PVC pipes together with 14/1 AWG direct burial wires. The PVC pipes will give me a bit extra protection and that's it. There won't be too much human activity between the ground mounts and the mechanical room, but kids would like walk over the buried pipes/wires from time to time.

What do you think about this? Also, do you have any recommendation on where to purchase online (in Canada preferably) the 14/1 AWG direct burial wires (black and red)?

Thanks,

[Mike90250]

Instead of water pipe (sch 40 PVC) use the gray electrical PVC which is rated for electrical. Yes, I know the wire inside is rated for direct burial, but using the right PVC does not cost all that much more, unless you already have a pile of water line sitting around

I'd put some sort of disconnect near the charge controllers, not just at the remote end of the array, much easier for maintenance & trouble shooting

[extrafu]

Instead of water pipe (sch 40 PVC) use the gray electrical PVC which is rated for electrical. Yes, I know the wire inside is rated for direct burial, but using the right PVC does not cost all that much more, unless you already have a pile of water line sitting around

I'd put some sort of disconnect near the charge controllers, not just at the remote end of the array, much easier for maintenance & trouble shooting

Thanks for your response Mike! I indeed had in mind gray electrical PVC, I probably mis-expressed myself. As for the DC disconnect box (Square D H361), it'll be right next to the CC, inside the mechanical room and not outside near the ground mounts.

[bcroe]

From my experience, it could be advantageous to break ALL the DC leads with the H361. Otherwise work
on the array could cause problems with the plant, a blown GFI fuse in my case. Bruce Roe

[Farlander]

How did it work out? I am building a similar system. I would have used thwn-2 inside conduit, #10 probably, and had at least two H361s at the CC's depending on if the H361 is rated to break both the positive and negative conductors depending on pole configuration. Does anybody know whether a single H361 is approved to break both the positive and negative conductors of a single string? (Required by NEC 2011 for ungrounded/floating arrays, which Schneider MPPT80 600 is by default)

Thanks

[extrafu]

I went with two small junction boxes for each ground mount. Then, from there, TECK cable 10/2 AWG from each junction box to each a H361 DC disconnect (inside the building). Then, from there, same TECK cable to a MPPT 600-80 CC (2 CCs total).

The system so far rocks big time. TONS of power.