Auxiliary Ground

[andrew.tkelly]

I'm presently working on getting a rooftop ballasted PV system permitted here in the SF Bay Area. I just got my electrical plan check comments back. There's basically only one:

Show compliance with Art. 690.47(D) Aux. Ground of the 2016 California Electrical Code.

All of the modules are on the roof, with the inverters and AC disco's being on the wall of the ground level. What is the easiest way to comply with this?

Thanks in advance.

Kind Regards,
Andy

 

[jaggedben]

Run a #8 ground from the roof and drive a ground rod below, say, the gutter that you're bringing your DC into. Irreversibly splice connections in between. If the rod would be right next to the foundation and you have UFER you might be able to invoke the 6ft exception. Or you might be able to anyway if near an existing electrode.

Or wait until 2020 when this stupidity goes away again.

 

[ggunn]

I'm presently working on getting a rooftop ballasted PV system permitted here in the SF Bay Area. I just got my electrical plan check comments back. There's basically only one:

Show compliance with Art. 690.47(D) Aux. Ground of the 2016 California Electrical Code.

All of the modules are on the roof, with the inverters and AC disco's being on the wall of the ground level. What is the easiest way to comply with this?

Thanks in advance.

Kind Regards,
Andy

I'm sorry for you. I have designed hundreds of PV systems, both residential and commercial, and in all those cases I have run into exactly one inspector on exactly one project who invoked and forced compliance with 690.47(D).

 

[BandGap1.1eV]

Show him the video where M. Holt describes how this aux. electrode is actually dangerous.

https://www.youtube.com/watch?v=WlnFNTay-9Q

It's an "auxiliary" item which by definition is not required. Then the specification it refers you to does not require this electrode to be installed like a normal electrode.

 

[pv_n00b]

I've been able to make exception 2 apply in just about every case. It only requires that you show that an acceptable location to install the aux electrode is within 6' of the existing grounding electrode system.

Exception No. 2: An additional array grounding electrode(s) shall not be required if located within 1.8 m (6 ft) of the premises wiring electrode.​

Since the aux electrode has to be mounted, "as close as practicable to the location of roof-mounted PV arrays," it's usually possible for that location to meet the exception. Keep in mind it does not say as close as possible to the array.