sizing ground wire for solar

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SeanD

Member
Just a thought, is this for the Enphase system from your other post. If this is for a micro-inverter system, remember no matter how well protected the GEC is under the array, it is not conduit.:grin: So consider 250.64 (B) for sizing considerations.
 

Smart $

Esteemed Member
Location
Ohio
Does the GEC from inverter of solar system have to be sized according to table 250.66?
690.47 doesn't really say one way or another, even if you follow all the references. Simply put, the inverter's(s') output is a grounded AC system and is thus grounded accordingly. IMO, the answer to your question is basically yes.

If this is a multiple micro-inverter system, you will likely have to resort to a common GEC for multiple separately derived systems [250.30(A)(4)], which cannot be smaller than 3/0 [250.30(A)(4)(a)], then tap conductors are sized per 250.66 [250.30(A)(4)(b)]... but I am unfamiliar with such an installation and only speculating in this regard.
 

Energy-Miser

Senior Member
Location
Maryland
Just a thought, is this for the Enphase system from your other post. If this is for a micro-inverter system, remember no matter how well protected the GEC is under the array, it is not conduit.:grin: So consider 250.64 (B) for sizing considerations.

Yes it is for the Enphase. Thanks,
 

SeanD

Member
Reading Smart $ post you can see there are multiply potentially conflicting code sections. 3/0 GEC seems a little extreme to me, but I am not that familiar with intent on that section of the code. I would work closely with the AHJ and get there take on it. The first Enphase system I worked on was a first for the AHJ as well and things worked out pretty well. Remember to bring the Enphase installation guide when you go speak to them.
 

dereckbc

Moderator
Staff member
Location
Plano, TX
Energy Miser. I suggest you go HERE and download the document. It will answer most of your PV code questions and give you a lot of installation practices. It is written by John Wiles the guy who wrote NEC 690

Hope that helps.
 
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SeanD

Member
I would never assume what I see in a marketing video is actually the way it should be installed. Taking a quick glance at the video I would guess they are using a #8 GEC. If I was an inspector I would say the installation in the video is NOT code compliant based on the code section I referenced in my original post.

Drive1968 you might want to take a look at NEC table 250.66.
 

drive1968

Senior Member
I agree the bare copper running from the junction box and being connected to the inverters looks like #8 and that is what I used in my installation. I guess I wasn't clear in what I meant in my earlier post. I was referring to the wires running to the junction box from under the roof. The circuit is protected by a 15 amp breaker, so the 2 hots, the neutral, and the ground would be within code with a 14 ga, depending on the distance of the run. I used 12 gauge and my inspector said it was code compliant.
 

drive1968

Senior Member
Sean, I guess it could be called a marketing video, but Enphase calls it a training video. In an installation such as this, particularly when the product is new, I think its important to follow manufacturer instructions as close as possible. Maybe I'm misinterpreting the NEC, but I think the manufacturer's video is NEC code compliant.
 

SeanD

Member
That explains the confusion. The OP is a question regarding sizing the GEC, so you threw me off with talking about conductors. My past posts cover why I feel the #8 as installed in the video is not code compliant. You can disagree with me all you want but the code section is pretty specific. Like I suggested to EM work with your AHJ if they are cool with #8, you are good to go. Just hope the Inspector doesn't brush up on sec. 250.64 after approving your plans and changes his mind at the time of inspection. :grin:
 
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