Bonding to a Metal Roof

[AE3]

I recently installed a 5kW system on a standing seam metal roof. I used S-5! seam clamps, Snap N Rack self bonded racking and Enphase M250's. It looks like the inspector might also want to see me bond to EVERY panel of the roof. Does anyone have a method they recommend? There is no way to put lay in lugs on the roof without puncturing something and putting an S-5! clamp on every seam (with a lay in lug on it) is not only ugly but also isn't valid. Any thoughts or recommendations?

[foo1bar]

I recently installed a 5kW system on a standing seam metal roof. I used S-5! seam clamps, Snap N Rack self bonded racking and Enphase M250's.

What is "self bonded racking"?

Do you mean racking with bonding mid-clamps?


I don't know about bonding metal roofs - I think you said in another post that you're in NY. And I see that apparently NY has it's own rules about bonding for metal roofs where equipment is mounted on it, so I think you're going to have to ask around locally to see what others in the area have done.

[Amy@altE]

You absolutely do not need to bond to the roof. I suggest you contact S-5!, as they will likely have documentation you can use to prove your point.

[foo1bar]

You absolutely do not need to bond to the roof.

Are you sure?

NY apparently has this section of code:
"E3509.1 General. Bonding shall be provided where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed. Where electrical equipment is mounted on conductive roofing or siding, it shall be bonded to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed."

I think if the AHJ says the roof needs to be bonded, the AHJ has what they need to justify it.

I haven't lived in NY for many years, and I'm not claiming to be an expert on this topic. But I stand behind my advice to find someone locally who has dealt with it before. (Possibly you can even ask the building inspector for help with finding someone)

[Amy@altE]

D'oh! I just got off the phone with S-5!. They have seen this new requirement and are actively trying to interpret it themselves. I had been in training with them previously where they had told us that you don't need to bond, but that was before this new requirement came up. I forwarded the link to them, they may be able to help.

[Mike90250]

Well, bonding to a steel roof, will damage the paint, and allow rust to start eating through. And the rust is not a good conductor. What a PITA.

[Amy@altE]

I had a long follow-up call with S-5 with a code expert. The answer is there is no good answer. He has met with AHJs on this matter. What could be a solution is to deal with the words "where ground fault is likely to be imposed". If you have proper wire management that prevents any wire touching the roof, and keeps critters from nibbling them, then it will be "unlikely" to have a ground fault, and therefore you are compliant.

[Sunking]

Two golden rules when dealing with AHJ and Wives

1. AHJ and Wives are always correct.
2. When AHJ and Wives are incorrect, refer to rule #1.

Point here is does not matter what the manufacture, installer, engineer, or whoever says or thinks. Only opinion and interpretation that counts is the AHJ.

[Amy@altE]

Agreed on both points. I'm on my phone and can't type much, there were many topics discussed. The gist of the conversation was that the AHJs he was meeting with were trying to figure out themselves what the code meant, and how to actually pass an installation. Easy to say you failed, harder to say what you want to see to make it pass.

[Sunking]

My POV an dI have worked many states on commercial projects is if there is any electrical on the roof and the roof is metal, it shall be bonded. That does not mean it has to be ran with PV conductors. I see it the same as a metal building and code does require all structural steel to be bonded. Really not hard or expensive to comply with. As for rust/corrosion is concerned a light coat of Samchem NO-OX-ID A Special will protect that until the building falls down. No battery system should be without it. It is what all utilities and water plants use. It will even protect chain link fences in NOLA for 30 years.

[foo1bar]

Really not hard or expensive to comply with.

We're talking about a metal standing seam roof, right?
I don't know how you'd attach a wire to that such that it'd actually have a good electrical connection.... The S-5 clamps don't look like they would do it - they are probably designed to *not* pierce the paint.
I don't know of anything that's intended to make such a bonding connection ( much less something that's UL listed)

bonding structural steel in buildings is something that is a near-universal requirement - so there are items commonly used to make those connections.
But doing a standing seam roof seems like it's not common at all - so if you know what manufacturer has a suitable part, I'm sure the OP will appreciate it.