On Sun, 14 Mar 2010 18:21:14 -0400, mm wrote:

On Sun, 14 Mar 2010 17:41:46 -0400, "The Henchman"
wrote:



"RBM" wrote in message
...

"The Henchman" wrote in message
...
We have a 1969 Fuse box, using 12 gauge copper wire, 100 amp service.

Long story short We were told by our home insurance and home inspection
people that in Ontario (Canada), there are no concerns with inspected
copper wired fuse boxes until they reach 50 years. So we are not rushing
to replace this box. However I wanted to install GFI receptacles for
outside, kitchen, and two bathrooms. There are none in place now. We
also have a 240 volt outside outlet to run a pool motor.

Can GFI work on fuse boxes/panels? if so, does that GFI outlet, when
tripped, mean replacing the fuse? Do all the GFI's have to be on the
same circuit?

Anyone have any advice on this matter?


The most expensive thing to do would be to use GFCI circuit breakers,
assuming you did want to replace the fuse panel. Just install GFCI type
outlets at the areas you want to protect, and do as the others recommend
for the 240 volt pool outlet.


Let me make sure I got this right. If not somebody tell me.

So I can use a GFCI OUTLET and that will give me protection without having
anything to do with the fuse box? It'll trip at the outlet only but offers
protection. I have fuses, not circuit breakers. I don't want fuses blowing
if the outlet trips.

Yes, that's all you need do. If you want to make sure, buy one and
replace one, and then push the Test button and see if you blow a fuse.

Yes, and you can get a "three light tester" with a GFCI tester built in for
$10 or so, at your local HomeDespot. Plug it into any outlet, push the button
and see if that outlet is protected.

Last time I had fuses, I lived in an apartment and the owner made sure
they were slow-blo fuses, so he woudn't be bothered to replace the
ones in the basement all the time But I'm 99 percent sure all fuses
are slower to blow than GFI's are to trip. For one thing, there
isn't necessarily, usually isn't iiuc, almost never is maybe, any
short when a GFI trips. It trips because the ground wire is not good,
not connected or something. That's not a short.

A GFCI tripping won't blow the *fastest* fuse. It doesn't have anything to do
with the current in the line, rather the current imbalance between the hot and
the neutral. If the current in the hot isn't the same as the current in the
neutral there is a Ground Fault and the Circuit is Interrupted. ;-)

As to the word only that you use. There is normally a string of
receptacles or ceiling lights or on some occasions a combination of
the two with the fuse or cb at one end of the string. The GFI
receptacle will, when wired the right way, not only protect itself,
but each of the receptacles that are further away, electrically, from
the fuse than the GFI is. Because if there isn't a good ground to
the GFI, then there isn't a good ground to any of the receptacles that
are further away either. Well that's garbled probably, but smething
like that.

THe GFCI measures the difference in the current in the Hot and Neutral wire.
The imbalance can occur anywhere after the measuring device and the switch
will trip. GFCIs even work in ungrounded circuits. Indeed, they're *highly*
recommended in places where there are no grounds.

If I can get protection at the outlet only, on a fuse system, that will be a
safe and sufficient solution? We will replace the fuse box for a circuit
breaker 5 years from now.

Why?

Because it's a good idea but not an emergency repair.