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
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
On Wed, 29 Nov 2006 00:22:47 -0600, snipped-for-privacy@UNLISTED.com wrote:
Evidently the current flow through the fan to your hand, through your
body, throught your shoes to the ground was below the threshold of
the GFI. That path presented enough resistance to current flow to
limit it to a small enough value that the GFI didn't trip. Placing
the fan on the floor provided a lower resistance path so he current
was high enough to trip the GFI.
GFI's will allow a small amount of fault current to flow without
tripping. This reduces nuisance tripping, but still provides
protection against dangerous levels of current. There was enough
current to feel (which is very little) but not enough to be dangerous.
Seems like the GFI did its job, and you were smart to do the test you
head to home despot or lowesers (or better yet a local place) and
purchase a little outlet tester.
3 lights indicate the wiring, and a button tests GFCIs. Much better for
testing GFCIs than the test button on the outlet.
Also, GFCI breakers are much more sensitive (and faster) than GFCI
outlets. I converted a circuit from GFCI outlet to GFCI breaker, just
for fun I tested the GFCI outlet on the circuit with the GFCI breaker.
Breaker was faster than the outlet.
The test you did doesn't prove GFCI breakers are more sensitive and
faster than GFCI outlets. It just proves that the particular pair you
had behaved that way.
To the OP, what were you standing on, type of shoes, etc or in contact
with when you got the shock? It does seem that the current you got
was less than the amount needed to trip the GFCI.
On 29 Nov 2006 07:24:10 -0800, firstname.lastname@example.org wrote:
The first way to check if the case is grounded is by looking at the
plug. It has to have 3 prongs to be grounded.
If it is a two prong plug, and it sounds like that is what it is, It
will not be grounded.
This was a problem. Most likely you can flip the plug in the
receptacle and the "shock" will go away.
The hot is connected to the case in one situation and connected to the
switch for the motor lead in the other.
They came out with polarized plugs to assure that the hot is connected
to the load first.
Good grief! If that were true, don;'t you think there would be an
awful lot of people dead from decades ago? I don;t know of any
appliances with a metal case, where if you simply plugged the cord in
one way vs the other, you could wind up dead, because the case is now
On 29 Nov 2006 11:01:28 -0800, email@example.com wrote:
There were more electricution deaths in the past. Much of that old
stuff was more dangerous than the newer stuff. I cant begin to count
the number of times I got shocked when I was younger (in the 60's and
70's). Most of the time people are not killed, just shocked....
It was leakage, not direct short in most instances......
Those old metal encased power tools, as well as "hot chassis" radios
and tvs were the worst. I'd say the most shocks I got when I was
younger were from the old metal electric drills. Now they are plastic
cased, have 3 prong plugs or polarized plugs. Much safer....
Electricity is much safer these days.
I had an old tube type short wave radio when I was a kid. I ran a
long wire out the house to garage for an antenna. That radio had a
"hot chassis" In other words, if the plug was in one way, the chassis
was direct to the 120VAC. If reversed, it was hooked to the neutral.
So one day I had it turned on and connected the antenna wire, then was
going to connect the ground wire (shortwave antennas need a ground).
As I connected this ground wire, the thin wire literally burned off
the insulation and left a nasty burn on my hand. The house filled
with smoke and my dad got really pissed and was going to throw the
radio away. After he calmed down he called his brother (my uncle),
who was an electrician. He installed a polarized grounded plug on my
radio, and we never had another problem with it. The days of having
to reverse the plug are no longer an issue.
On 29 Nov 2006 07:15:42 -0800, firstname.lastname@example.org wrote:
It's NOT. This is probably a 1940's or 50's fan. No ground wire to
the outlet. Just the old 2 prong plugs which is all that was used on
that old stuff. When I get a box of stuff at those auctions for a
couple bucks, I dont waste too much time fixing the bad stuff unless
it's really valuable. I really did not need another fan anyhow, but
there were lots of other goodies in the box. I always test all the
stuff as soon as I get home and discard the bad stuff so it's not
Do you happen to know whether this is by design or is it just "always
And if by design, why?
I wouldn't think it would be difficult for the designers to set roughly
equal sensing levels/times in both types.
I have to claim 'just in my experience' based on a few cases, I did
read something awhile ago and can't find the darn thing.
One common sense reason to claim the breaker 'more sensitive' though is
that the breaker will 'see' more wiring and equipment, and so the
background leakage the breaker sees will be higher than that which an
outlet will see (even if chained to a few more outlets).
Since the background leakage will be higher, the amount of fault
current required to hit the magic number of total leakage current
(usually 4-6mA) will be less.
On 29 Nov 2006 06:58:59 -0800, email@example.com wrote:
Cement garage floor, leather shoes that were somewhat wet from walking
to the garage after a rain storm. I ONLY felt the shock on my
fingers. I was not touching anything with my other hand or other body
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.
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.
Certainly seems that the current through the GFCI should be unbalanced.
The only way it would be possibile for it to be equal would be if
you grabbed one part of the fan that was shorted to hot, and another
that was connected to neutral.
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