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Old 23rd Feb 2019, 1:40 pm   #136
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Join Date: Nov 2009
Location: Lincolnshire, UK.
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Default Re: Modern MK Safety Plug. Not impressed

Originally Posted by broadgage View Post
Most other types of mains plugs were suitable for AC or DC, as were the matching sockets. Regulations required that sockets on DC supplies had switches. This was optional for AC.
Not just ordinary micro break switches as on the standard 13 amp AC sockets of today, but large throw/break type switches to break DC at high voltage due to the half cycle not going through zero and into reverse to break the arc. Just pulling out a plug on a 240 volt DC supply without switching it off first could produce quite a 'flash' in some cases and eventually burn the contacts of the pins if not pulled cleanly and quickly. If you'd used an AC type 13 amp socket with a crude micro break switch as used today, then you'd probably have the equivalent to a welders arc form between the switch contacts within the socket (depending on current) and it probably wouldn't even switch off and break the circuit - very dangerous!
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