Grounding electrode on helical pier ground mount solar arrays

[BackCountry]

We have a few ground mount solar arrays in the job queue, and as I was doing takeoffs to prep for material orders, I wondered... do 16 helical piers embedded 5’+ into the soil supporting a ground mount solar array, with a UL2703 compliant racking system that’s bonded throughout, qualify as the grounding electrode thereby eliminating the need to drive a second ground rod? These are microinverter based systems, so the entire array is bonded, and no DC leaves the array, It’s all AC. We have a pier mounted AC disconnect where we will tie the ground in from the main panel. From there, we’ll have a #6 bare copper that’s bonded to the racking and frame. Clearly driving an additional ground rod isn’t expensive or difficult; however, logically speaking it’s difficult for me to think that it’s doing something when I’ve got 16 galvanized piers with 5 feet of direct earth contact each right next to it. Please educate me, when reading the NEC steel structure used as a grounding electrode or UFER ground sections, my situation does not appear to clearly qualify.

 

[electrofelon]

Yeah it is just about the dumbest thing in the world that it doesn't qualify. I would install the rods at night or on the weekend so no one sees, I'd be so embarrassed at having to do such a dumb thing

 

[jaggedben]

If you can make one of those piers 10ft then boom, there's your electrode.

 

[wwhitney]

Seems like 8ft would be enough, isn't the shaft of the helical pier a pipe of diameter at least 3/4" trade size?

Cheers, Wayne

 

[jaggedben]

Seems like 8ft would be enough, isn't the shaft of the helical pier a pipe of diameter at least 3/4" trade size?

Cheers, Wayne

Ok, but you'd need two of them, because a single pipe electrode requires a supplemental electrode. (250.53(2)).

 

[winnie]

If you think about the size of the helix then the piers should also be good as plate electrodes even though not 8' deep.

I don't think these piers qualify as grounding electrodes but should. I wonder if the manufacturer could get them listed as grounding electrodes as a selling point.

Jon

 

[BackCountry]

I wonder that too. There will be 16 of them, embedded 5 feet deep each. It seems like there would be more than adequate earth contact; however, not something I'd want to experiment with unless it was recognized in the code. They're great for ground mount solar, racking within an hour or two of arrival at a job.