On Saturday, July 27, 2019 at 11:31:50 AM UTC-4, Arlen G. Holder wrote:
From the US homeowner's perspective of working backward from a wall outlet
o What is the difference between ground and neutral in the US?

Both should be at close to the same potential. Only the neutral should
be carrying any current during normal operation. The ground is there to
shunt a fault, ie a hot wire comes in contact with a metal case and to
keep all the metal at close to earth potential.




A friend is debugging why the washing machine metal case is hot only when
the water pipes are hooked up and water flowing through them when I tried
to explain to that homeowner over the phone the difference between ground
and neutral - where - I'm not sure I have it all figured out myself.

If it's hot only when water is flowing, then it must be because for water
to flow, the WM is powered on and activating the solenoid valves, not
because of the water. Something is seriously screwed.




I'm going to point her to this answer on the net.

You should point her to an electrician or someone who's qualified.




*Is this correct for ground?*
o It's the round hole in a 3-hole outlet
o It's usually a bare copper wire (or sometimes green).
o It's connected to the sub panel without any breaks whatsoever.
o From the sub panel it connects to the main panel sans any breaks.
o From the main panel it goes directly to the main inlet cold water pipe.

Only if there is a metal pipe.




o From that main cold water inlet pipe, it goes into a stake in the ground.

No, it doesn't have to be wired serially, in that order.


o It should never carry current unless there is a problem somewhere.
o Therefore, the voltage from it to the ground should be zero.

I'd say close to zero, the neutral carries current, with substantial
current you could see some voltage difference, but not a dangerous level.

The rest is correct.


*Is this correct for neutral?*
o It's the taller slot in the typical grounded US outlet box.
o It's the white insulated wire (when black or red is the hot wire).
o It's connected to the sub panel but it may have connections between.

Anything, including grounds are typically connected somewhere in between.



o From the sub panel it connects to the main panel sans any breaks.
o From the main panel it goes directly to the power company input.
o Generally that power company input will be a power pole.
o Within a few power poles will be the step-down transformer.
o From that step-down transformer the neutral will go into the ground.

Yes, and it's connected to the transformer center-tap too, which is the
most important part.

o Therefore, the voltage from the outlet neutral to ground should be close to 0

In a way, they're similar in that both the ground and neutral eventually go
directly into the ground - but they're different in that the neutral
carries current while the ground only carries current when something is
wrong.

Before I point the homeowner to this thread, can you clarify or fix
mistakes in my understanding of the difference between neutral & ground?