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From: "Phil Allison"
Subject: Re: Wall wart with two blade polarized plug,,,Why?
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Date: Sat, 5 Oct 2002 15:30:44 +1000
NNTP-Posting-Date: Sat, 05 Oct 2002 15:18:55 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"Bob Wilson" wrote in message
> In article ,
> > ** Wall warts with DC output are NEVER auto- transformers. That
> >would, be extremely dangerous.
> > .. . . . . . .Phil
> Some years ago, I asked a similar question to a CSA guy. The Wall Wart in
> question actually had a 3rd ground pin. I asked what on earth was the
> for this. He said it was necessary to endure a safety ground. So I asked
> "Precisely WHAT is it that is being grounded? After all, the transformer
> itself had to be certified for its isolation, and the wall wart housing is
> plastic. There is NOTHING to ground!". His response? "Oh! I never thought
> about that!"
** The ( unconnected) earth pin is often included for a more secure
fit in the outlet - so the wart will not easily dislodge.
> I then asked why my Bosch hand drill that was CSA/UL certified as "double
> insulated" had to have a 2-prong polarized plug. He said it was to ensure
> the correct part of the drill was connected to neutral. So I said "You
> forced the manufacturer to make the drill double insulared, and
> intrinsically safe. Now you say that the polarized plug is needed. Are you
> telling me that you don't trust your own safety standards?". Much
> backpedalling ensued!
** Well - it is nice if the switch is in the active and not the
neutral. All Aussie plugs are polarised - we have two flat but angled-in
pins for A and N and a slightly longer one for ground. It can only go in
one way even if there is no ground pin fittd to the plug.
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