Sorry, I meant to type higher resistance. On my water heater, the equivalent part that is glowing in the picture is a really thin flexible corrugated gas pipe that surely can carry much much less current than the iron gas pipe feeding it before it went really high resistance. I could totally see it glowing like this with enough current.

My gas pipe to the house comes out of the ground inside a plastic protective pipe sleeve, so I can imagine it possibly not having enough of a low resistance path to earth to trip one of the cutout fuses on the primary distribution line. Granted, mine also has a big ground wire bonding it to the house ground, which I would think would help here…

/shrug I was just sharing what I read. It was supposedly the explanation as to why local breakers on the house didn’t trip.