| "Peter W." <peterwieck33@gmail.com>: Apr 11 11:25AM -0700 > If you can plug a polarized plug into a non-polarized receptacle, then > you can defeat the safety advantage offered by the polarized plugs. NEMA receptacles (1-15P) for polarized plugs have been around since the late 1920s when the concept of 120/240 AC systems was fully described. We have them in some old wiring in our house. NP (1-15) receptacles exist for situations where the polarity of the receptacle cannot be predicted - such as DC circuits, and 'back-panel' receptacles in devices such are clock-radios that might be plugged into the wall either way. Many more contemporary audio devices used NP receptacles in the back (especially tube stuff) rather than polarized as they sometimes hummed less if plugged in one way rather than another. Polarized *receptacles* offer 'safety advantages' only if they are correctly wired. Polarized *plugs* offer safety advantages again, only if they are properly wired and the device is functioning properly. These distinctions are lost on our Non-North American friends. After all, it was all pretty much invented here, and the rest of the world benefitted by not having to make the same mistakes we did in the beginning. Nor are they living with 110 year-old wiring as we are (1913). It is perfectly fine, by the way, and called "knob and tube". It has also been inspected by our insurance company and passed without a peep. Peter Wieck Melrose Park, PA |
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