ORIGINAL MESSAGE:
On Tue, 3 Nov 2009 22:34:40 -0600, "Gary Schafer" <garyschafer@comcast.net>
wrote:
>
>If they are both bonded at the appliance both will carry neutral currents.
>That can raise the appliance case above ground due to voltage drop in the
>cable. Should neutral and ground become open somewhere in their path that
>would put full line voltage on the appliance case.
REPLY:
My dense little brain finally got it.
To reiterate: The danger comes when neutral and ground are bonded together at
the appliance AND both neutral and ground wires back to the service entrance
become open. Under that circumstance, at least some of the "hot" AC will appear
on the chassis of the appliance. This assumes that within the appliance there is
a load of some kind between one or both of the "hots" to neutral. If there was
no such load, you wouldn't need the neutral in the first place.
On the other hand, if they are NOT bonded together at the chassis and both wires
back to the service entrance become open, AC will NOT appear on the chassis
unless there is an actual short between one of the "hots" and the chassis. .
Thanks for sticking with me. :-)
73, Bill W6WRT
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