Is there a coupling in the vertical conduit above the enclosure? Rigid conduit couplings do not keep water out where they are installed in a vertical run. One reason why many specs prohibit top entry in wet locations.
I was surprised to see it took 23 posts before someone mentioned condensation - it was my first thought. Those hubs don't leak as a general rule, at least not enough to be significant, more water condenses in connected raceways and drains to whatever is below than what leaks through the fittings, and on top of that it don't have to be rainy weather, condensation can happen on a daily basis in some locations rain or shine.It's likely condensation inside the conduit, air seal the conduit at openings to keep humid air from entering and then condensing when the temperature drops.
The issue at water heaters is not the thread sealing compound it is dissimilar metals causing gavalanic corrosion - therefore they often use an isolating fitting that is intentionally designed to not have continuity through the fitting.Do you use thread sealant for rigid threaded conduit?
Don’t that prevent conduit Continuity same like on water heater so we need to use bonding wire
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