Hi Ron,
The concept you're pondering is one that's confusing to every apprentice we
instruct. Yes, it is electrically the same. Function is the difference.
The neutral wire is a current carrying conductor by intent. The ground or
earth wire is a safety path to ensure all framework is at the same electrical
potential.
A corollary to your premise would ask why a seaman in a boatswains chair
would have a safety lanyard?? Just hang him over the side with the same rope,
right? ;-))
I have never really understood the mania on this third wire or "Ground" wire
in the US since 99.9% of all electrical panels have the supposedly "Neutral"
wire and the "ground" wire connect to the same buss. In the UK where all
the two wire plugs are actually both hot (two phases of 120) 220 volt - it
makes good since to have a separate ground wire - but in the US each outlet
already has a ground wire, I don't see the reason you need two - It's even
sillier now on the 220 appliances because you now have to have 4 wires
instead of three - 2, 120 wires and 1 ground and now lets add another ground
wire.
Just hook up a wire form the ground screw on the back of the outlet to the
neutral (white side) on the back of the plug - and you have the exact same
circuit as if you had hooked the ground wire to the white wire at the panel.
Stick in one of those fancy three light testers and you'll see what I mean.
Ron (closet electrician) Schmittou
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