AC polarisation. Does it matter?

(The AC polarity could also be off on the wall plug. No reason to believe the crew that installed the outlets in the house got all the wires put on the plugs the right way. They work very fast.)

They had better get the polarity correct or it can cause very severe problems with certain components. A cable box for instance will have 110 volts on it's coax center conductor if the recepticle is wired backwards.

I should point out that some devices use polarized plugs for safty reasons and if reversed could cause shocks, fires or damaged equipment. One such episode happened to me with the afore mentioned cable box where an electrician had wired the recepticle for an audio video system backwards. When I attempted to connect the cable box, the coax arced when I touched it to the connector and burned out the box. It could have wiped out the whole system which consisted of a very expensive plasma TV. I f a device you have has a polarized plug, I would not reverse it unless authorized by the manufacturer.