🚀 go-pugleaf

In article <92836@netnews.upenn.edu> george@mech.seas.upenn.edu writes:
>:
>:In older metal appliances, before the 3rd grounding pin, one of the
>:120 lines were attached to the case of the appliance to be used as a
>:ground.  Back then there was no standard side of the 120 to be used as
>:ground so either one was used.. 
>
>but..but.. polarized plugs ( it seems ) weren't common until
>the mid 70's ( remember the little explanatory tags ).  Three prong
>grounded plugs were available long before that ( no? )

You're right.  Under no circumstances was it _ever_ permissible to
connect one side of the 120V line to the case of the appliance.

In 1950, you used a 3-prong grounded plug if you wanted/needed to ground
the case of the appliance; otherwise you used a 2-prong UN-polarized plug.

Gradually it was realized that lots of things could be made safer
(w.r.t. likely short circuits, effects of blown fuses, etc.) if you
could be sure which side of the line was closer to ground potential.
Hence the polarized plug.

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