Why can some (US) outlets fit a plug from either way you put it in, but some plugs have a fatter and skinnier prong?
In: 8026
This isn’t relevant for the ELI5, but in Britain, even though there are only 2 wires (live and neutral), there is an amazingly complicated system. Sets of plugs are connected in a ‘ring main’ configuration, all in parallel one to the next and back to the beginning, so neutral, live, and ground are all three in parallel. Then, neutral and live are brought separately *outside the house* and connected together *outside the house* and also ground is connected to something in contact with the ground. Also the ground (but NOT neutral) is connected to all pipes inside the house.
This is so safe that people have electric showers and no-one ever gets hurt, even though at twice the voltage, there is four times the shocking energy.
One reason this works is, if any one wire breaks behind the wall, connecting one plug to another, it will not matter (that is the point of the ‘ring main’ configuration). But also since the ‘ring mains’ are in small groups, there is not too much power dependence on any one wire even after the break.
Another feature of this is, with all these wires securely intact and with redundancy, if there is ever a short between live and ground in the house, electricity will have to go outdoors and go through the place outdoors where neutral and live are connected, hence through the fusebox and exceed the current capacity and blow a fuse.
Nowadays there is RCD circiutry which also detecgts this, but the point is, this system works independently of RCD.
So, going back to your question about switching the orientation of a plug, if it ever happens that in say an electric drill, the neutral and live wires were switched internally, and neutral connected to the case of the drill such that now live and ground are both connected to the case, that connection will create a circuit whereby electricity has to leave the house to cmplete the short circuit, blowing a fuse, even if the RCD system fails.
Neutral and ground are functionally equivalent, but there is this system that detects that they are kept distinct everywhere inside the house.
This makes sure that it can never happen that there can be like a pipe next to an electric shower which is live, while the water in the shower is neutral, etc.
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