Properly wiring AC disconnect help needed..

[Sgtnarc1]

Need help in determining where to properly connect wires inside AC disconnect. I have attached the Electrical diagram to save time in explaining the set up.

Question is, where inside the AC disconnect switch do I connect the wires coming from the solar array side? Do they go on the Line or Load side lugs? Whichever it is then the wires going into the Service panel would go on the opposite lugs.

I want to get this right before I start cutting wires.

Thanks.


Electrical plan.png

[PVAndy]

Wire the breaker in the main panel to the line side of the AC disconnect. Neutral & EGC to the appropriate terminals in the main panel. Do not bond N & G in disco. Load side of fused disconnect to inverter. N & G don't need to be same size as L1 & L2

Andy

[Sgtnarc1]

Andy,

Thanks for the response and explaining where to connect the various wires.

A little confused when you mentioned that the Neutral does not need to be the same size as L1 & L2. The electrical drawing show L1,L2 and Neutral as 3 AWG going into the Service panel.

I should have mentioned previously that I have already cut and run the red, black and white 3 AWG wires from the Service panel into the AC disconnect. Should I have run the Neutral (white) directly from the Load Center thru the AC disconnect and into the Service Panel without cutting? I bought a Neutral kit for the AC disconnect. Should I attach it the the disconnect and use it for the Neutrals or run a new 3AWG.

Edit.....Just noticed that I have enough 3AWG Neutral wire (white) to pull thru directly to the Service panel.

[Salts]

N & G don't need to be same size as L1 & L2

Andy

HUH?????? I get that ground doesn't need to be the same size, but the neutral has to be able to carry whatever current L1 or L2 can carry.

[Sgtnarc1]

Salt,

Now that that is cleared up, do I run the Neutral straight thru the Disconnect and terminate it in the Service panel. Also does the Disconnect need to be grounded?

[Salts]

Salt,

Now that that is cleared up, do I run the Neutral straight thru the Disconnect and terminate it in the Service panel. Also does the Disconnect need to be grounded?

Yes, run the neutral straight through to your main service panel. Yes, the disconnect needs to have an earth ground. Anything that is a part of your electrical system that is made of metal or electrically conductive should have an earth ground, and it needs to be bonded back to the main service panel...

[Sgtnarc1]

Salt,

Thanks for that info. A question on the bonding. That would be a copper wire attached to the AC Disconnect box which then terminates in the MSP on the grd terminal correct?

[Salts]

Salt,

Thanks for that info. A question on the bonding. That would be a copper wire attached to the AC Disconnect box which then terminates in the MSP on the grd terminal correct?

Yup. If the disconnect doesn't have a grounding terminal, you can drill a hole through the side, scrap paint away, ad some anti-ox compound, and put a machine screw through it with a star-washer. But ya, copper wire running from the metal box to the combined neutral / ground in the main service panel.

You just have to make sure if the box ever becomes energized for some reason (Broken wire insulation, someone decides its a great place to hide a mylar balloon, etc) that the current goes to ground through a copper wire and not a human.

[Mike90250]

Yup. If the disconnect doesn't have a grounding terminal, you can drill a hole through the side, scrap paint away, ad some anti-ox compound, and put a machine screw through it with a star-washer.......

Drilling a box and using a star washer is not a approved grounding method in my area. I'm glad it works for you. it doesn't for me.

[Sgtnarc1]

Mike90250,

What is the approved method in your area?

[Salts]

Drilling a box and using a star washer is not a approved grounding method in my area. I'm glad it works for you. it doesn't for me.

What is the approved method for your area? None of the sub panels or breaker boxes I purchased came with frame grounds in them. My electrical inspector didn't have any problem with it at all.
And if a manufacturer did put a frame ground in them, isn't that what they would essentially do anyhow?

[bcroe]

I have some box grounding strips, which I bolt to the inside of the box with a couple screws. Some
had a place reserved, others I just drilled. Bruce Roe

[PVAndy]

S

Now that that is cleared up, do I run the Neutral straight thru the Disconnect and terminate it in the Service panel. Also does the Disconnect need to be grounded?

Please don't take all the info you receive on this forum as gospel. Starting with the 2011 NEC the neutral conductor can be sized the same as the EGC. It is not a current carrying conductor and is only used as a voltage reference.

See
705.95 Ampacity of Neutral Conductor. The ampacity of the neutral conductors shall comply with either (A) or (B). (A) Neutral Conductor for Single Phase, 2-Wire Inverter Output. If a single-phase, 2-wire inverter output is connected to the neutral and one ungrounded conductor (only) of a 3-wire system or of a 3-phase, 4-wire, wye-connected system, the maximum load connected between the neutral and any one ungrounded conductor plus the inverter output rating shall not exceed the ampacity of the neutral conductor. (B) Neutral Conductor for Instrumentation, Voltage, Detection or Phase Detection. A conductor used solely for instrumentation, voltage detection, or phase detection and connected to a single-phase or 3-phase interactive inverter, shall be permitted to be sized at less than the ampacity of the other current-carrying conductors and shall be sized equal to or larger than the equipment grounding conductor. The operation of the inverter in the presence of load currents tends to decrease currents in the neutral. If a neutral conductor is associated with a circuit supplying both power and instrumentation loads, 705.95(A) applies to sizing of the neutral conductor

[Salts]

Please don't take all the info you receive on this forum as gospel. Starting with the 2011 NEC the neutral conductor can be sized the same as the EGC. It is not a current carrying conductor and is only used as a voltage reference.

See
705.95 Ampacity of Neutral Conductor. The ampacity of the neutral conductors shall comply with either (A) or (B). (A) Neutral Conductor for Single Phase, 2-Wire Inverter Output. If a single-phase, 2-wire inverter output is connected to the neutral and one ungrounded conductor (only) of a 3-wire system or of a 3-phase, 4-wire, wye-connected system, the maximum load connected between the neutral and any one ungrounded conductor plus the inverter output rating shall not exceed the ampacity of the neutral conductor. (B) Neutral Conductor for Instrumentation, Voltage, Detection or Phase Detection. A conductor used solely for instrumentation, voltage detection, or phase detection and connected to a single-phase or 3-phase interactive inverter, shall be permitted to be sized at less than the ampacity of the other current-carrying conductors and shall be sized equal to or larger than the equipment grounding conductor. The operation of the inverter in the presence of load currents tends to decrease currents in the neutral. If a neutral conductor is associated with a circuit supplying both power and instrumentation loads, 705.95(A) applies to sizing of the neutral conductor

Damn.. I wonder if an electrical inspector would even know this. I'd bet my barn that the guy in my town wouldn't know.

[Mike90250]

Some areas, drilling a box is "modifying" and then the box looses it's rating. And you have to use approved hardware, stainless starwasher. I had to use the prefab greenwire crimped into a ring terminal, at $3 each before my inspector was happy. All depends on who you get.