Got quite a scare the other day:
One moment I was cheerily plugging in and unplugging my 100 W light bulb for testing current measurements, and the next it came apart with a huge bang. No fuse tripped anywhere (as it would have in UK households).
It’s a good reminder of the amount of energy an AC power outlet can discharge at any time. In fact, the standard rating for individually-fused 220 V power groups is 16 Amps around here. That’s roughly 3600 W.
To get an idea of what that means – one Horsepower is the sustained power a horse can generate, which is about 740 Watt. So there are almost 5 horses in each power outlet, waiting to charge at you!
If you push that much energy into a liter of water, it’ll boil in 2 minutes flat. Doesn’t sound like much, eh? How about 1000 Amps at 3.3V? You’ll need copper wire with a diameter of 18 mm to handle that much current.
Compare that to a JeeNode in sleep mode drawing 10 µA, i.e. 33 microwatt. That’s 8 orders of magnitude less.
Anyway, I’ve gained some extra respect for 220V mains circuits.
Now, if only I could find a replacement … 100 W incandescent light bulbs are no longer sold in Europe.