[acquacow]

That certainly shouldn't be able to happen. The top of panel breaker should pop with a large enough load, and the mains on the street can handle quite a number of homes with supply. There's no way a single in-home unit should/could pop anything at a substation. The component at the substation likely just failed at that time.

[xattt]

I am wondering if there were no household loads on that circuit that had that level of in-rush current, the component was on its way out, and the new load pushed it over the edge.