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Does anyone know whether/how you are supposed to electrically ground metal roofs? This is for an 80s era pieced together house, off-grid, that has a pieced together 80s era solar PV system on the roof. Apparently it might have been lightning struck over New Years and there were discharges within it. Not sure if that's what happened, but the owner is now wondering about grounding.
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I don't know about the roof, but Code requires grounding for the PV panel frames.
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At the class i took they used a big gauge wire to contact each of the aluminum rails that cradle the pv panels. I should have asked why the wire so fat. Is it going catch fire??
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PV ground wire is both fat and direct so that it becomes the "path of least resistance".
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I know that quite heavy gauge wires were used to ground the main panel (4 or 6ga copper I believe) in my recently built Fern Forest house. I also grounded my TV antenna and mast with 6ga copper. I had a lightning strike to the structure shortly thereafter. Don't ask me why, but the lightning apparently did not strike the high antenna mast. It sounded like someone had fired a 30.06 in the back room when it happened. No damage to electrical stuff in the house, though the CRT monitor on my computer (which was on at the time) turned an odd bluish shade for a few minutes. I later found a scorched area in the exterior paint surrounding a nail head at the bottom of the trim on the corner of the house. Even later, when I moved a metal-framed ironing board which had been stored in the house in the same corner, I found a scorched area on it where it touched the concrete floor.
A side note for dog owners. I hear that metal-cable dog runs can route lightning strikes into cable tethers attached to your pet on the line. Might be prudent to assure your dog isn't vulnerable to this potential hazard.
