Which type of system do I use? Suggestions

[RShackleford]

Ground mount ... Disadvantages ... May/Probably need a fence around it for safety

Just asked my AHJ of ground-mount would need a fence, and he said "no, maybe if you're in a city". I'm on 5 acres, although he didn't know this, just that he's a county inspector (not responsible for the several largish towns in our county). We are, however, subject to 2017 NEC.

I asked about the 600vdc one could have if using strings, and what about children, and he wasn't worried.

Forgot to ask him, but is another advantage of ground-mounted that rapid-shutdown would not be required ?

[SunEagle]

Just asked my AHJ of ground-mount would need a fence, and he said "no, maybe if you're in a city". I'm on 5 acres, although he didn't know this, just that he's a county inspector (not responsible for the several largish towns in our county). We are, however, subject to 2017 NEC.

I asked about the 600vdc one could have if using strings, and what about children, and he wasn't worried.

Forgot to ask him, but is another advantage of ground-mounted that rapid-shutdown would not be required ?

Rapid shutdown is really designed for home roof tops where first responders may be on but need to be protected from getting electrocuted. I do not believe rapid shutdown is needed for a ground mount although I am surprised your AHJ did not require some type of barrier or fence to keep out people or animals.

[RShackleford]

Rapid shutdown is really designed for home roof tops where first responders may be on but need to be protected from getting electrocuted. I do not believe rapid shutdown is needed for a ground mount

I think you're right. But there is another issue, that of the high-voltage DC strings coming into the house (where my string inverter etc will be, in a utility room where the main panel lives). My understanding is the high-voltage cannot be more than 3ft on the outside from where it enters the building, or 5ft on the inside after it enters the building. Unfortunately, due to other buried wiring (since the DC will be coming to the house in buried conduit from the ground-mounted panels), it'll be impossible for me to have the DC enter the building less than 5ft from where the inverter is located. Does this mean I have to do rapid-shutdown ? Or if I protect the inside wiring before the inverter well enough, in conduit, am I cool ?

I am surprised your AHJ did not require some type of barrier or fence to keep out people or animals.

Yeah, this is one of those grey areas I guess. I need to somehow pin the AHJ down on this. If they're gonna make me build a fence, maybe I'd rather just raise the thing up to whatever height eliminates that need, whatever that is (probably another grey area). One thought I had, if the '-' conductor on your DC strings is somehow referenced to ground, and if you have your strings vertically oriented with the '+' conductor at the top, well then even a ground-mounted system would not have dangerous voltages near ground level (you close the loop with a cable from the bottom up to the top, and run the two conductors into conduit down into the ground from there).

What is the best way to pin the AHJ down on these issues ? Make a detailed drawing of the system, and submit it when I get the permit ? Then when the permit is approved, I'm covered ?

[SunEagle]

I think you're right. But there is another issue, that of the high-voltage DC strings coming into the house (where my string inverter etc will be, in a utility room where the main panel lives). My understanding is the high-voltage cannot be more than 3ft on the outside from where it enters the building, or 5ft on the inside after it enters the building. Unfortunately, due to other buried wiring (since the DC will be coming to the house in buried conduit from the ground-mounted panels), it'll be impossible for me to have the DC enter the building less than 5ft from where the inverter is located. Does this mean I have to do rapid-shutdown ? Or if I protect the inside wiring before the inverter well enough, in conduit, am I cool ?


Yeah, this is one of those grey areas I guess. I need to somehow pin the AHJ down on this. If they're gonna make me build a fence, maybe I'd rather just raise the thing up to whatever height eliminates that need, whatever that is (probably another grey area). One thought I had, if the '-' conductor on your DC strings is somehow referenced to ground, and if you have your strings vertically oriented with the '+' conductor at the top, well then even a ground-mounted system would not have dangerous voltages near ground level (you close the loop with a cable from the bottom up to the top, and run the two conductors into conduit down into the ground from there).

What is the best way to pin the AHJ down on these issues ? Make a detailed drawing of the system, and submit it when I get the permit ? Then when the permit is approved, I'm covered ?

If you only have one AHJ then an approved set of drawings should convince them to approve the installation. Unfortunately if there is more than one AHJ you might run into a preference issue that does not agree with one of the others.

[Ampster]

I am not clear what the distances are from the high voltage DC. The only thing my AHJ wants to see is the DC in metal conduit. If you follow the advice of @Suneagle and label the distances on your plans you can get that clarified over the counter when you obtain your permit.

[RShackleford]

If you only have one AHJ then an approved set of drawings should convince them to approve the installation. Unfortunately if there is more than one AHJ you might run into a preference issue that does not agree with one of the others.

I'm actually not sure what AHJ means (I know what the letters stand for) - I just use the term to sound cool. Does multiple AHJs mean multiple jurisdictions that might have authority (e.g. town and county) or does it simply mean there's more than one human inspector person at whichever it is (just the county, in my case) ? The latter could be the case, although I think I can ask for one guy.

But at any rate, it seems like if my drawings are signed off on, then everybody needs to honor that. FWIW, the inspectors in my county don't seem to take pride in being dicks, really quite the opposite; very unlike what I've seen reported at other forums for other parts of the country.

I am not clear what the distances are from the high voltage DC. The only thing my AHJ wants to see is the DC in metal conduit. If you follow the advice of @Suneagle and label the distances on your plans you can get that clarified over the counter when you obtain your permit.

Yeah, I don't see how anyone an object if it's in sturdy conduit (I'd probably use Schedule 80 PVC).

[SunEagle]

@SunEagle This is the second time this has happened at this subforum today. I make a post, it goes through. Then I edit it - a very minor edit (I try to make my posts as clear andd legible as possible) - and when I go to "Save" it then flags it as needing moderator approval. Annoying for me, extra work for you. Anyhow, thanks for your help.

Sorry. It might be due to the latest software changes after the server was hacked. Hopefully our IT department will get it straightened out.

[Ampster]

Sorry. It might be due to the latest software changes after the server was hacked. Hopefully our IT department will get it straightened out.

I thought it was me when I was in a kerfuffle with @J.P.M. Good to know I can be candid again. LOL.