For those saying to bond the skin of the building, got an nec article number? Do you guys also bond aluminum siding, window trim, and gutters?
The skin does not require a bond, imo.
Most gas piping is already electrically bonded thru your furnace circuits ground wire. Csst requires a separate bonding conductor installed per manufacturers recomendatiin.
Exposed is ok normally, subject to damage is not. As stated above that's open to interpretation. If run horizontally at 4 ft I'd say probably no go more often than not. If run vertically then I'd say lower than 18 inches is probably a no go. That's just me and what I've installed in Michigan...
The code compliancy I spoke of, is in regards to the manufacturers instructions. Listing agencies require you to install per manufacturers instructions. Instructions state gfci receptacle, not gfci protected ckt. It's really splitting hairs, and most inspectors are good with something like that...
Would it trip receptacle before the breaker? Tough to say, sometimes yes sometimes no. Would you be ok with just the breaker? Yes. Code compliant? Debateable. Imo just install it off of your gfi protected ckt.