Appreciate that wire is not electrically same at both
ends. Wire is not a perfect conductor. Wire is treated as if
it was another electronic component. How much difference
exists between two ends of a wire is determined by
characteristics of the current in that wire - ie. amperes,
open circuit driving voltage, frequency, harmonics, etc. Most
of this will be well beyond the scope of this discussion.

But human safety demands that any electrical appliance be
connected as best as possible to the safety ground inside
breaker box panel (point where safety ground wires, white
neutral wire, utility neutral wire, and earth ground wire all
meet). The only wire that can make such a connection is one
that is not carrying any current - the bare ground wire. Even
though the white neutral wire also meets at that point, the
white wire has significant differences at both ends - because
white wire is carrying up to 20 amps current.

Others have provided examples of why the white wire and bare
safety ground wire are completely different wires at the wall
receptacle. Bottom line - the white wire and bare safety
ground wire are only same where both meet at the breaker box
safety ground.

You may even be able to see this difference with a digital
volt meter. When AC outlet powers a significant load (ie
toaster or steam iron), then a voltage difference should exist
between white neutral wire and bare copper safety ground wire
at that wall receptacle.

Are white neutral and bare copper safety wires properly
isolated? Breaker box GFCIs tend to trip (cut off power) when
bare copper white is shorted (connected) to white neutral wire
anywhere but inside the breaker box. Just another in a long
list of examples that demonstrate why white neutral and bare
copper safety ground wire are electrically different. Why one
wire cannot perform both functions.



Doesn't a similar situation exist under the hood of your car?

Two wires emerge from the alternator, a thick one and a thin one, and both
go to the positive pole of the battery.
I wonder how many people have stood pondered why that might be?

Graham.

%Profound_observation%