[Arran]

Polarized plugs on an AC set, that is a set with a power transformer, are a waste of time, the chassis is already isolated from the power line aside from the line capacitor/s across the primary. I also think that they are of dubious value on most AC/DC sets, Philco AC/Dc sets are NOT hot chassis sets, the common negative, or B-, side is not connected through the chassis like some brand Z and cheap brands, it has it's own wiring.
Regards
Arran