Brother in law had a fire in his house trailer last night, mattress next to an outlet caught fire and no one hurt but this is what he found. An overloaded circuit I'm sure with a window ac and three other black wires,and three whites coming off the duplex in question, and don't know where they go to. He cleaned up the work box, reset the 15 amp breaker, turned on the ac and the 100 amp breaker tripped on the outside pole, the 15 amp breaker did not trip. any thoughts here......