GFCI Troubleshooting

Posted by Robert Green on October 17, 2009, 1:07 am

> Don't know where the op is from, or where you're from, so I'm just
> specifying U.S. code

US near Washington, DC. The giant hole where all US citizens' tax dollars
shoot out of like an Eastern version of the Ol' Faithful geyser. (-:

I will probably end up following the CEC's recommendations, anyway, even
though the NEC governs here, simply because the Canadian rules happen to
make a lot of sense. I'm guessing that frequency of nuisance trips of a new
GFCI gets about as low as possible with only one appliance on that circuit.
It also seems that accidental trips for any reason are reduced by dedicating
a line to the breaker. My own experience backs that up. Two GFCI trips per
year with some other heavy-duty equipment on the same line as the fridge
suggests the refrigerator does not trip the GFCI itself.

The GFCI unit that trips about every six months is a Slater, not a Leviton,
it turns out. I've had it since GFCI's first arrived in the consumer
mainstream. It could easily be close to 25 years old which means a more
modern version might not even make those 2 nuisance trips a year even with
other gear on the line and the problem's solved!

I am going to swap the old unit out and the new 20A Leviton GFCI in its
place after I "dedicate" the line from the breaker to the refrigerator. I
just feel more comfortable with shock protection on the refrigerator and
accept that replacing a fridge worth of food is a possible consequence. It
just seems that possibly replacing frozen food is a better option in the
long run than finding yourself planning a funeral from a freak accident with
a funky fridge. What's that line from "Casino" - "You can have the money
AND the hammer?"

--
Bobby G.

Posted by Robert Green on October 16, 2009, 6:55 pm

<stuff snipped>
> The Nec doesn't required dedicated circuit for a refrigerator
<stuff snipped>
> The Nec requires ALL counter top and island receptacles to be gfci

protected

That's interesting and in line with what I thought to be true about
electrical requirements for my particular jurisdiction. Even though a
dedicated circuit is not required, I can certainly see the wisdom in putting
a "mission critical" device like a refrigerator on its own breaker so that
no other errant device can take it down.

Thanks for the input. I'm going to ask the local inspector what the county
wants in the way of GFCI's and dedicated circuits. He's the one that
matters most. I don't think it could hurt things to dedicate a line, but
what I really want to know now is whether there's any advantage to
protecting the refrigerator with a GFCI. It's close to the sink and it's
made at least partly of steel - it seems to be an "at risk" area. A lot
I've read about using GFCI's note that the newer units are far less likely
to nuisance trip than older models. Some also say that there are some
GFCI's designed to trip at a higher-than-normal current imbalance, but the
higher the trip level, the more of a shock gets through to pen closing the
circuit,

--
Bobby G.

Posted by RBM on October 17, 2009, 7:09 am

>> The Nec doesn't required dedicated circuit for a refrigerator
>> The Nec requires ALL counter top and island receptacles to be gfci

> protected
> That's interesting and in line with what I thought to be true about
> electrical requirements for my particular jurisdiction. Even though a
> dedicated circuit is not required, I can certainly see the wisdom in
> putting
> a "mission critical" device like a refrigerator on its own breaker so that
> no other errant device can take it down.
> Thanks for the input. I'm going to ask the local inspector what the
> county
> wants in the way of GFCI's and dedicated circuits. He's the one that
> matters most. I don't think it could hurt things to dedicate a line, but
> what I really want to know now is whether there's any advantage to
> protecting the refrigerator with a GFCI. It's close to the sink and it's
> made at least partly of steel - it seems to be an "at risk" area. A lot
> I've read about using GFCI's note that the newer units are far less likely
> to nuisance trip than older models. Some also say that there are some
> GFCI's designed to trip at a higher-than-normal current imbalance, but the
> higher the trip level, the more of a shock gets through to pen closing the
> circuit,
> --
> Bobby G.

When I said that the Nec doesn't require a dedicated circuit for a fridge, I
didn't mean to imply that a dedicated circuit wasn't a good idea, or even
required by the refrigerator manufacturer. Nec is a minimum requirement. If
your fridge is in a kitchen, and the outlet is behind the fridge, gfci
protection is not required. If the circuit and outlet are properly grounded,
it will be perfectly safe, and not vulnerable to ground fault related
anomalies

Posted by Robert Green on October 21, 2009, 4:10 am

> When I said that the Nec doesn't require a dedicated circuit for a fridge,

> didn't mean to imply that a dedicated circuit wasn't a good idea, or even
> required by the refrigerator manufacturer. Nec is a minimum requirement.

Understood. If the Canadians think a dedicated line is a good idea, I
assume they've got reasons based on experience. There are lots of good
reasons to dedicate a line, like making it easier to supply just that device
with a generator or not having to shut it off to service any other devices
on that circuit. It's so cheap and easy that it's almost crazy NOT to do
it.

> If your fridge is in a kitchen, and the outlet is behind the fridge, gfci
> protection is not required. If the circuit and outlet are properly

grounded,

> it will be perfectly safe, and not vulnerable to ground fault related
> anomalies

Why does having the outlet blocked have anything to do with it? Not sure I
follow that reasoning.

Isn't the whole purpose of having something like a GFCI to act as a "last
line of defense" in case something very unlikely occurs like a cord getting
frayed and passing power to the metal case? Even a little current leakage
might be enough to kill someone. From what I recall, it doesn't take much
current, if delivered across the heart, to cause death. I would think if
there was no real protective value that the NEC would say so, instead of
appearing to gradually bring GFCI's into the code in nearly all
circumstances.

Now arc-fault interrupters seem to be a more contentious case. The folks I
know that have installed them report they are plagued with nuisance
tripping. I wonder if it's just another case of it taking time for the
manufacturers to fine tune the product?

--
Bobby G.

Posted by bud-- on October 21, 2009, 11:03 am

Robert Green wrote:

>
>

>> When I said that the Nec doesn't require a dedicated circuit for a fridge,

> I

>> didn't mean to imply that a dedicated circuit wasn't a good idea, or even
>> required by the refrigerator manufacturer. Nec is a minimum requirement.

>
> Understood. If the Canadians think a dedicated line is a good idea, I
> assume they've got reasons based on experience. There are lots of good
> reasons to dedicate a line, like making it easier to supply just that device
> with a generator or not having to shut it off to service any other devices
> on that circuit. It's so cheap and easy that it's almost crazy NOT to do
> it.
>

>> If your fridge is in a kitchen, and the outlet is behind the fridge, gfci
>> protection is not required. If the circuit and outlet are properly
>> grounded,
>> it will be perfectly safe, and not vulnerable to ground fault related
>> anomalies

>
> Why does having the outlet blocked have anything to do with it? Not sure I
> follow that reasoning.

Kitchen countertop receptacles have to be GFCI protected. A receptacle
behind a refrigerator is not a countertop receptacle.

> Isn't the whole purpose of having something like a GFCI to act as a "last
> line of defense" in case something very unlikely occurs like a cord getting
> frayed and passing power to the metal case? Even a little current leakage
> might be enough to kill someone.

The requirement for commercial kitchens to have refrigeration on GFCI
receptacles was because people were getting shocks. (Homes probably have
greater care taken of equipment.)

> Now arc-fault interrupters seem to be a more contentious case. The folks I
> know that have installed them report they are plagued with nuisance
> tripping. I wonder if it's just another case of it taking time for the
> manufacturers to fine tune the product?

Starting 2008 much more sensitive AFCIs were required. The old ones
detected a 75A arc (and would only detect an arc from H-N or H-G).
Starting 2009 they have to detect a 5A arc (and can detect a loose
arcing connection). I would think detecting a 5A arc without tripping on
normal arcs (like turning off a switch) would be a real challenge.
At the same time (IMHO a dumb idea) they were required for far more
areas of a house.

I haven't heard about major nuisance trips. Have other people?

--
bud--

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