When I was a kid my dad bought me a cassette recorder that operated on both mains and batteries. I always carried the thing around with me, taping songs on the radio etc. I never used the AC power adaptor on the unit. One day, the batteries ran flat. Now, I thought because it had an AC power port, it’s the same as batteries. So, I stripped a piece of cabtyre and fixed the live and neutral to the battery points Pos and Neg. I then plugged it into the wall socket and switched on the switch
BANG!!.
Now, luckily for South African domestic electricity laws, all electrical circuits are protected with both an Earth Leakage and Mini Circuit breaker rated at 16A for a series of plugs.
The resulting flash blackened the whole wall, tripped all the power in the house. The best part was that I decided to do this little experiment in my parent’s bedroom. Needles to say, I had to please and explain why the house smelt like burnt electronics and why the whole wall, that once was as white as milk now look like charcoal?