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Ungrounded Handy Box crhras 07-24-2007
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Posted by crhras on July 24, 2007, 3:39 pm
Just spent the last two hours trying to figure out why the GFCI my
electrician installed in my new building doesn't trip correctly (that
includes at trip to the shop to get a new GFCI). I found out that the box
it is using as a ground isn't grounded. Another box 2 feet away is grounded
just fine and the GFCI housed by it trips under all tests.

What do electricians do in this case ? There's conduit to the box and I'm
wondering why it wouldn't be grounded in the first place. I'm thinking of
pulling a third copper wire and using that to ground the outlet but that
probably isn't the best solution.

Thanks



Posted by dpb on July 24, 2007, 7:29 pm
crhras wrote:
> Just spent the last two hours trying to figure out why the GFCI my
> electrician installed in my new building doesn't trip correctly (that
> includes at trip to the shop to get a new GFCI). I found out that the box
> it is using as a ground isn't grounded. Another box 2 feet away is grounded
> just fine and the GFCI housed by it trips under all tests.
>
> What do electricians do in this case ? There's conduit to the box and I'm
> wondering why it wouldn't be grounded in the first place. I'm thinking of
> pulling a third copper wire and using that to ground the outlet but that
> probably isn't the best solution.

If, as it sounds, you're talking a metal box and conduit, it should be
grounded. About the only way it can't be if the box feeding it is is if
the conduit isn't continuous or there was a plastic fitting used
somewhere. My first preference would be to fix the conduit rather than
pull another ground.

--

Posted by crhras on July 25, 2007, 12:12 pm
>
> My first preference would be to fix the conduit rather than pull another
> ground.
>

That would be my first preference also but I can't imagine how one would
find where the conduit is open. I mean, it could be anywhere in the wall,
right ?



Posted by Bobk207 on July 24, 2007, 9:40 pm
> Just spent the last two hours trying to figure out why the GFCI my
> electrician installed in my new building doesn't trip correctly (that
> includes at trip to the shop to get a new GFCI). I found out that the box
> it is using as a ground isn't grounded. Another box 2 feet away is grounded
> just fine and the GFCI housed by it trips under all tests.
>
> What do electricians do in this case ? There's conduit to the box and I'm
> wondering why it wouldn't be grounded in the first place. I'm thinking of
> pulling a third copper wire and using that to ground the outlet but that
> probably isn't the best solution.
>
> Thanks

There must be something else going on.

A GFI will trip even if not grounded properly. That's why the GFI
comes with stickers that say "no equipment ground".

A GFI compares the hot current to the neutral current & based on a
difference; trips.

I've installed GFI's in old houses w/o grounds (& applied the
sticker) ......they trip just fine.

cheers
Bob


Posted by crhras on July 25, 2007, 12:02 pm
>> Just spent the last two hours trying to figure out why the GFCI my
>> electrician installed in my new building doesn't trip correctly (that
>> includes at trip to the shop to get a new GFCI). I found out that the
>> box
>> it is using as a ground isn't grounded. Another box 2 feet away is
>> grounded
>> just fine and the GFCI housed by it trips under all tests.
>>
>> What do electricians do in this case ? There's conduit to the box and
>> I'm
>> wondering why it wouldn't be grounded in the first place. I'm thinking
>> of
>> pulling a third copper wire and using that to ground the outlet but that
>> probably isn't the best solution.
>>
>> Thanks
>
> There must be something else going on.
>
> A GFI will trip even if not grounded properly. That's why the GFI
> comes with stickers that say "no equipment ground".
>
> A GFI compares the hot current to the neutral current & based on a
> difference; trips.
>
> I've installed GFI's in old houses w/o grounds (& applied the
> sticker) ......they trip just fine.
>
> cheers
> Bob
>

The GFCI trips just fine when using it's self test button. It doesn't trip
when using the GFCI test button on the small outlet tester I am using. All
other (10 or so) GFCI outlets in the building trip when using the tester on
them but some of them didn't before I grounded them to the boxes they are
installed in.

The tester has three lights on it - 2 yellow and one red and when an outlet
is well grounded to the box the 2 yellow lights are bright and the red one
is completely off. When an outlet doesn't seem to be grounded the two
yellow lights are lit but not too brighly and the red one glows a bit. The
instructions that came with the tester don't address what that means. I am
assuming that something is not right.

So, after doing everything possible to ground the GFCI to it's box I then
used a meter to measure the voltage difference between the hot lead and the
box. The voltage measured only 60V whereas a different, working box
measured 120V. That's why I assumed the box is not grounded.

Finally, I just hanged a copper wire from the ground screw of the
non-working GFCI to a good box and it then trips correctly.

Thanks the responses,
Curt



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