From: terrell.michael.a@gmail.com   
      
   On Sunday, April 23, 2023 at 3:18:25 PM UTC-4, vjp...@at.biost   
   ategist.dot.dot.com wrote:   
   > Wow, thank you. Exactly the answer I wanted.    
   >    
   >    
   > *+- 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 benefited 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   
      
   It is often forgotten, but Thomas Edison used 110/220 in his DC system. 110   
   was used for lighting, 220 was to power motors and heaters. It was simple to   
   convert a business or  home's wiring from DC to AC, by simply changing the   
   feed to the building.   
      
   We added a bedroom to my parent's home in the early '60s, and Polarized   
   outlets were already in use.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)