On Wed, 29 Nov 2006 18:06:47 GMT, "Pop`"
wrote:

Warren Block wrote:
wrote:
I just went to an auction and came home with a whole bunch of old
junk. One of them was an old metal framed swivel house fan. I am
always leary of that old stuff, so I always test it in a GFI outlet.

I plugged it in, and reached to flip the metal switch. When I
touched it, I got a fairly good jolt on my fingers. The GFI did NOT
trip. WHY? I thought that was the whole purpose of having them.
This GFI was just purchased and installed, and the test button works
fine.

Two-prong plug on the fan, right?

The amount of current on the hot line is the same as that on the
neutral. So as far as the GFI is concerned, there's no ground fault.
It can't tell if it's just the fan motor between hot and neutral, or
the fan motor and you.

GFI, Ground Fault Interruptor is a misnomer. "Ground" in the original case
may have been ground, but now, because of poor terminology, is considered
the Neutral conductor. How a GFCI operates has nothing to do with the
ground. Since it senses differences in current between the hot/neutral
conductors, any third wire earth ground is irrelevant to its opeartion. Hot
amps = Neutral amps, all OK. Not equal, it trips. It's literally that
simple.

Pop`



Just for the heck of it, I plugged the fan in again, and had the
switch already turned on. The fan ran just fine on a wooden table.
Then I set it on the cement garage floor and plugged it in again, and
the GFI tripped instantly. For the heck of it, I put a piece of wood
under it (on the floor) and the GFI did not trip. This proves that
fan motor has leakage to the metal housing, so it goes in the
garbage. But I can not understand why the GFI did not trip when my
fingers got shocked ????

The cement floor provided a current path to ground, so the amount of
current on the neutral was different from what was on the hot. The
GFI sees that difference and trips.






I think of "ground" being the ground connection that you DON'T want.
That is, the circuit being grounded through you.
--
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Mark Lloyd
http://notstupid.laughingsquid.com

"Unlike biological evolution. 'intelligent design' is
not a genuine scientific theory and, therefore, has
no place in the curriculum of our nation's public
school classes." -- Ted Kennedy