why are there separate neutral and ground wires for electricity when they both are connected to the same thing.
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Electricity always wants to get back to its source. The “neutral” wire is how it gets there in normal operation. However, if something breaks and electrifies the casing of something metal, and you touch it while touching the actual ground, it *could* try to go through you. Which is bad. By providing an actual “ground” wire, you provide a quick, low resistance path back to that neutral line, which will almost certainly trip the breaker and/or GFCI.
As for why they are separate wires at the plug when they pretty much always get connected at the panel there are a few reasons. Primarily, if you just used the neutral as this safety line, the casing would always be part of the circuit, which presents a slight possibility of shocking you if it has a voltage relative to something else you touch. Other faults can make this very dangerous. You wouldn’t want to grab on to a wire sticking out of the neutral slot on a socket would you, even if theoretically safe?
The other reason is that it allows GFCIs to work (those outlets that you have to reset in your bathroom sometimes). They are able to detect if the amount of power going “out” through the hot wire is different than the amount coming “back” through the neutral wire. If it is different, this means power is going somewhere it isn’t supposed to be, usually through that ground wire, and it will trip, shutting off power. If the neutral was used as the safety, the GFCI would have no way to know.
There may be some other nuance to this, but I believe that’s the gist of it. I always had this same question so it took me a while to understand as well. Also, as I understand it, the grounding rod actually in the ground connected to your panel has more to do with lightning protection than anything to do with the “ground” on your plug. Though I believe it is still connected and can be something of a backup to that.
One last fun fact – any metal piping in your house is also probably wired to the “ground” in your panel to provide yet another relatively safe path back for any rogue electricity, again, hopefully just tripping the breaker for the source.
Edited for clarity.
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