Bill,
Grounded conductors (neutrals) and grounding conductors (equipment grounds)
follow different rules, are connected differently, may be sized differently,
and sometimes follow different paths. The number of possible problems are too
numerous to ponder. One example follows.
The local chief electrical inspector was asked to investigate the death of a
young woman by electrocution while using an electric lawn mower. The findings
he relayed were:
· The girl’s father had made multiple repairs to the extension cord over
the years since it occasionally got ran over by the lawnmower.
· The ground prong broke off the extension cord. The father knew just
enough about electricity to be dangerous. He decided to tie the neutral to
ground at one of the spots where the cord was previously repaired.
(contributing mistake #1)
· The girl plugged the cord into a receptacle inside the house instead
of the GFCI receptacle outside to keep the dog from tampering with the end of
the cord. (contributing mistake #2)
· The cord was plugged into the receptacle backwards since it was no
longer polarized by the ground prong. The lawnmower frame was now energized,
sitting on insulating wheels.
· The daughter decided to mow the lawn in her bare feet. (contributing
mistake #3)
She was toast the moment she grabbed hold of the handle.
Jim Smith, EE
KQ6UV
That wasn't my question. Please forgive me if I wasn't clear enough.
My question was this: I understand why it is necessary to bond ground and
neutral together at the service box, but I don't understand why it is forbidden
to bond them together at the appliance.
There must be a scenario which causes danger but I just can't imagine what it
is.
73, Bill W6WRT
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|