Can I use Romex 10/2 to go from String Inverter to AC Disconnect?

[samotlietuvis]

Guys, I am drawing my first permit for 8 panels in one string of 2616W total DC Power. On DC side I will use #10 Cu AWG ”USE-2” wire with #6 Cu AWG bare ground to go from the panels to the inverter. I only have a roll on white #10 AWG USE-2 wire. Can use white “USE-2” wire for both positive and negative, or do I need to get different color, or somehow label the wires?

My transformerless string Inverter SMA 3000TL-US will be inside the garage, and it has maximum output current of 15A at 240VAC. Romex 10/2 is good for 30A. My question is if there will be problem with me using Romex 10/2 to connect inverter to AC disconnect that sits on the outside wall of the garage? The Romex 10/2 will be inside garage only.

Since I am using a transformerless inverter, I do not need to ground the inverter using grounding electrode. However, if I use Romex 10/2 in the garage, that means I will have ground conductor mismatch on the DC and AC side - #6 CU AWG bare ground on DC side, and #10 AWG ground that is inside Romex 10/2 on AC side, even though my inverter in transformeless. Is that against the code?

Another question is if I am allowed to use generic Air Conditioner AC disconnect available at Home Depot that costs $13 - AC Disconnect 30 Amp 2-Pole Fusible NEMA 3R
http://www.homedepot.com/p/GE-30-Amp...specifications
It is “Type Air Conditioner “. Is there any difference between Solar AC disconnect and Air Conditioner AC disconnect?

Thanks,
Tomas

[sensij]

Guys, I am drawing my first permit for 8 panels in one string of 2616W total DC Power. On DC side I will use #10 Cu AWG ”USE-2” wire with #6 Cu AWG bare ground to go from the panels to the inverter. I only have a roll on white #10 AWG USE-2 wire. Can use white “USE-2” wire for both positive and negative, or do I need to get different color, or somehow label the wires?

Thanks,
Tomas

If you are using white wire for any conductor on the DC side, you can expect to re-do it when the inspector sees it. The DC side of a SB3000TL is ungrounded, which means white is the one color you can't use.

Since I am using a transformerless inverter, I do not need to ground the inverter using grounding electrode.

Seek professional help.

[samotlietuvis]

If you are using white wire for any conductor on the DC side, you can expect to re-do it when the inspector sees it. The DC side of a SB3000TL is ungrounded, which means white is the one color you can't use.



Seek professional help.

sensij, thank you for advice regarding DC wire. I will get different color roll.


Attached is image on why transformerless inverter does not need to be grounded itself using grounding electrode. Grounding the transformerless inverter via AC line to the busbar panel that is grounded to the house main grounding electrode is per code as far as I am aware, but please correct me if I am wrong, or the inspector will correct me.

Thanks

TransformelessInverter Picture.jpg

[samotlietuvis]

Table 250.122 specifies minimum grounding conductor size based on OCPD. In my case, with 20A C/B, #12 AWG Cu ground cable in the garage will meet the code.