Service call way back...dead short, 20 amp, 120 circuit, resi.
Long to quick version..after 45 min of checking & tracing, found a receptacle that was on wall with bed against wall, sideways.
Turns out the kid was counting coins, dropped a quarter which magically crossed the hot/neut of a lamp cord cap that was not fully inserted.
Lucky...the bed did not ignite from the arc, and the repeated "on" the HO did before he called for help!
That's 25 cents turning into $125.00!!