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Old 08-29-2021, 08:35 AM   #5
s675
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Join Date: Sep 2015
City & State: Essex
My Country: UK
Line Voltage: 240VAC 50Hz
I'm a: Knowledge Seeker
Posts: 28
Default Re: WARNING: Live heatsinks & single pole on/off switches in switching power supplies

Here in the UK most of our circuit breakers at the main board (consumer unit) are single pole. If the incoming supply before the board is reversed, you end up with the situation where everything remains live.

Our wall sockets have switches but a lot of them are also single pole, so with the reversed incoming connection, you can turn off the PSU switch, turn off the switch at the socket, and turn off the circuit breaker, and the PSU will still be at 240v unless its switch is on the neutral (quite common).

Also, I learned this heatsink live situation the hard way yesterday!

Last edited by s675; 08-29-2021 at 08:37 AM..
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