On Sunday, July 28, 2019 at 1:16:27 PM UTC-4, trader_4 wrote:
On Sunday, July 28, 2019 at 12:09:58 PM UTC-4, Dean Hoffman wrote:
On 7/27/19 10:31 AM, 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.

This doesn't look quite right to me. Electricity tries to return
to its source
through all available routes, not to ground. You can have a lamp and
a tv running
on the same circuit, for example. Two lamps with incandescent bulbs of
different wattage will work on the same circuit.
Ground rods are for lightning protection. They won't do any real good
if there is a short to ground somewhere in the system.



What's not right is that if the panel, the circuit to the house and the
washing machine are correctly wired, the metal case of the washing machine
can't be hot. A fault inside the washing machine, eg the hot coming
into contact with the case, would cause a short that would trip the
breaker. You could not have the case of the washing machine be hot.
The path of the current would be from the hot at the panel, through the
fault in the washing machine, back through the ground conductor, tripping
the breaker. Clearly that ground path from the case back to the panel
does not exist. This all would work even if the neutral was not earthed
back at the panel, which is a side issue. One prime purpose of that,
like you say, is to provide a path for lightning, but it also provides
a common reference point for the whole system, so that faults to earth
don't behave unpredictably.

Correct that first sentence to read what I meant to say:


What's not right is that if the panel, to the washing machine and
the washing machine are correctly wired, the metal case of the washing
machine can't be hot.