From: John Woodgate
Subject: Re: Wall wart with two blade polarized plug,,,Why?
Date: Mon, 7 Oct 2002 06:32:18 +0100
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Mon, 7 Oct 2002 08:12:42 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Spehro Pefhany
wrote (in ) about 'Wall wart with two blade polarized
plug,,,Why?', on Sun, 6 Oct 2002:
>The renowned John Woodgate wrote:
>> That is OK in UK because the mains plugs are polarized, but in many
>> Continental countries the Schuko connector is used, which is reversible.
>> There are other, less widely used, connectors that are also reversible.
>Presumably that is why when we buy a "universal" PC supply we find the
>DPST switch breaks both sides of the line. That used to be very much
>frowned upon by the safety agencies (breaking or fusing the neutral).
It's a requirement of IEC/EN 60950 to have a double-pole switch if the
equipment can be connected to the supply through a reversible connector
(Case B of Table 2E), and in many European countries, it is so
connected. I don't know whether that provision is in UL950.
It is not required to have 2 fuses, except for Case C of Table 2E (US
240 V supply).
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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