This will show my naivety when it comes to alternating current... but why are some plugs and sockets on AC outlets polarized (one prong is taller than the other)?
My thought is that if the current is alternating that the hot and neutral effectively switch roles every 60th of a second. (50 if you're in Europe!)
I can't seem to wrap my head around why any device would care which line is hot or neutral, since the current coming into the device might come from either side. Wouldn't the safest option for implementing an on/off switch be to disconnect both sides for off?
Phrased differently, if I connect only neutral to a device, why doesn't it conduct to ground in the same manner as the hot line?