Depth for In Ground Pipe as Grounding Electrode

[BarklieEstes]

Hello,

We install ground mounted solar systems that use pile-driven 2" galvanized pipe for their foundation. We always install ground rods after we failed a couple inspections for not having them. Reading 250.52, it seems like that might not be necessary. Could we use the 2" galvanized pipe as our grounding electrode? If so, would it have to be 10' deep per 250.52(2) or could it be 8' deep per 250.52(5)? I don't think our equipment is capable of driving those posts much more than 8'.

Regards,
Barklie Estes

 

[LarryFine]

Barklie, that's a good question. It seems like a pipe has to be two feet longer if you attach something to it.

I would think that, as actual galvanized pipe, it qualifies as either one, so per 250.52(5), 8' should be enough.

If the inspector still has an issue over the 2' difference, ask if bonding two of them would allow the 8' length.

 

[jaggedben]

For what it's worth, since 2020 the NEC has explicitly permitted the support structure of a ground mounted PV array to act as electrode if it meets the requirements of 250.52. (690.47(B)).

We have discussed on this forum that rods do nothing for a support structure that already has many metal pipes in contact with the ground. I believe there was also a proposal to change the code on this for PV arrays but for some reason it didn't pass.

Anyway, as I read it, under 250.52(5), 8ft is good enough. Can't believe I didn't notice that before.

 

[acrwc10]

Barklie, that's a good question. It seems like a pipe has to be two feet longer if you attach something to it.

I would think that, as actual galvanized pipe, it qualifies as either one, so per 250.52(5), 8' should be enough.

If the inspector still has an issue over the 2' difference, ask if bonding two of them would allow the 8' length.

with the PV racks being attached all the pipes are bonded by default.

 

[LarryFine]

with the PV racks being attached all the pipes are bonded by default.

Does the mounting hardware qualify as an electrode connection?

 

[BarklieEstes]

Thanks everybody. The racking system we used is UL 2703 listed so every part of it is automatically bonded together. I think I'm going to put an extra 2' on our next one and see how it goes...

 

[jaggedben]

Does the mounting hardware qualify as an electrode connection?

Perhaps, if all the hardware between panels and pylon is listed for grounding and bonding per UL 2703. More likely you need a bonding jumper from the rails of the racking system rails to a listed 2" clamp on the pipe serving as the electrode. Or, if not not using UL 2703 listed rails (but that would be pretty stupid in 2024), then run a continuous jumper across all the solar modules (or groups of modules) that then goes to the electrode.

All of the above should also be bonded to any EGCs the system uses.