Electric Shock... a neophyte enquires

John Silk

New member
Apr 6, 2023
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Testing a piece of kit this morning with its non-earthed wall-wart power supply....

All was well; powered down and pulled mains plug... plug prongs touched the palm of my hand as I was moving towards packing everything away - probably 10 seconds after pulling the plug. I got a definite zap... way below mains strength obviously but enough for a small 'ouch'... never known that before in all my years...

What gives?
 
The capacitors in a power supply will store a charge for quite a while after AC is removed so it's good practice to disconnect from the wall first to let the powersupply discharge through the device it is powering.
 
Never treat capacitors badly. Pull plug and short pins with a screwdriver can make a huge bang and even melt the metal on some amplifiers. The ones in microwaves have killed people.