So what I finally found after isolating every switch, light, receptacle but one in the garage... after fifty years a simple ceramic light fixture, one with a grounded outlet and a pull chain, had the neutral and hot conductors inside the receptacle very close together inside. I don't know how it decided to fail after a three inch rain and thunder/lightening but it did. Lots of switches, light fixtures and receptacles to sort through in stifling heat and humidity but it's fixed. OK all you southwesterners... yes it was stifling for this northerner who whines when it gets above 80F.
