While we're on the topic of miswired outlets, here's another case I often get emails about on No~Shock~Zone. Of course, I tell them to start testing things one at a time, but many times this type of over-voltage fail will cause everything with a circuit board to be fried. See here for the link and below for the text:
http://www.noshockzone.org/accidentally-plugging-into-240-volt-outlet/So before you plug-in, Measure, then measure again. If anything looks the least bit funny, figure it out BEFORE you plug in your expensive sound gear.
Mike
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I just purchased a used 2003 Keystone RV 5th wheel from an individual. The TV and stereo was taken out. The microwave didn’t work. New frig. All 110 volts electrical, converter, battery, slid outs worked, using an extension cord plugged into an 20amp outlet in my garage, to my 30 amp / 120 volt TT cord. I purchased a RV Power Outlet 120 volt 30 amp [ provides an electrical receptacle in a single enclosure ] and a 30 amp breaker for my breaker box in my garage. I wired both black & white wires to the breaker & ground to the ground bar. [ Not thinking that gave 220 volts ] Bad mistake $$$$$$$. My ac still works, all battery devices [ lights, slide outs, power jacks ] works. My frig light works, but says no electrically. My GFI outlets work, but all 110 lights don’t, maybe more. Need all advice .