Path: utzoo!attcan!uunet!ncrlnk!ncrcae!hubcap!gatech!rutgers!bellcore!faline!sword!gamma!pyuxp!mruxb!wjm
From: wjm@mruxb.UUCP (mitchell)
Newsgroups: sci.electronics
Subject: RE: Polarized Plugs
Keywords: Polarized Plugs, Safety
Message-ID: <718@mruxb.UUCP>
Date: 10 Nov 88 15:56:46 GMT
Organization: Bellcore
Lines: 13


The reason 2-prong 120 volt plugs are polarized is for safety.  One side
of the common North American AC power system is connected to ground at
the service entrance panel.  This is in additon to the 3rd wire in
3-prong plugs, which is directly connected to ground.  Since some appliances,
like some TV sets, have the chassis directly connected one side of the line,
it is important that this side of the line be grounded!  Otherwise, someone
could get killed when touching both the chassis and something that is grounded
(like a water faucet or a properly grounded appliance).
This polarization is required by the National Electrical Code in the United
States as well as local electrical codes.
Regards,
Bill Mitchell