On Sat, 27 Jul 2019 15:31:46 -0000 (UTC), "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?

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.

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

*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.
o From that main cold water inlet pipe, it goes into a stake in the ground.
o It should never carry current unless there is a problem somewhere.
o Therefore, the voltage from it to the ground should be zero.

*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.
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.
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.

A pretty accurate assessment


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

The neutral (GroundED) conductor will see voltage drop imposed on it
that actually results in a higher voltage at the utilization site.
The bonding (the proposed term for the groundING) conductor is tied
directly to the earth via the grounding electrode system and in normal
operation should see no voltage drop so the case of your equipment
should be zero volts as compared to the concrete floor.

The one flaw in your description is theoretically the earth has no
affect on current flow. In reality that is not true, particularly with
wye distribution of the medium voltage at the transformer but your
local ground should still remain zero in reference to the grounding
conductor. The path for neutral current should be the grounded
conductor going back to the transformer.

In your friend's case I would first insure that there is no load side
panel (sub panel) involved and if so that the grounded and grounding
conductors are isolated in that panel and that the bonding jumper was
not installed. Also try unplugging the dryer, particularly if it is a
3 wire plug and the supplemental ground wire goes to the box the
washer is connected to.
If you eliminate that I would start looking at the grounding electrode
system. If it is just the cold water pipe, are you sure it is solid
metal all the way to the buried pipe outside and did that pipe
transition to plastic as soon as it left the house. That is not
unusual in any home built in the last 30-40 years. The NEC has
required a supplemental electrode for at least that long. That can be
a pair of 8' rods 6 feet apart connected by 6ga copper wire to the
grounding bus in the service disconnect enclosure or the meter pan.
Inspect the connections to those rods and the integrity of that
grounding conductor.