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Old 19th Jan 2012, 11:57 pm   #61
Phil G4SPZ
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Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
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Default Re: Another unusual plug and some other questions

Quote:
Originally Posted by AndiiT View Post
a switch which would not move to the on position until the plug was inserted and the plug could not be removed once the switch was in the on position.
Interlocked plugs and sockets were widely used in hospitals as a precaution against causing explosions in operating theatres due to the flammable anaesthetic gases in use. Notched earth pins fitted sockets which had a sparkless mercury bottle tilt-switch behind the fascia plate. Wandsworth and Walsall were popular makes.

I also seem to recall 13-amp BS1363 plugs with the earth pin set at 90 degrees to the live and neutral, and I think these were unfused plugs made specially for mobile X-ray machines to restrict their use to special sockets with a very low source impedance.

Interesting thread, this!
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