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Old 12-15-2008, 01:45 PM   #1
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Shocking kitchen appliance


I realize what I did was dumb but did it break a a brand new mixer?

I live in an old house and will hopefully be upgrading my kitchen very soon. As it is, all of the wiring is 12 gauge (with ground) NM from the 1970's. Unfortunately, it's all tied to an older 15 amp circuit without a ground.

However, all of the receptacles are protected by a GFCI.

Last night, I used a "brand new" very expensive mixer that I received several years ago as a gift, for the first time. It required a grounded outlet and w/out thinking, I simply placed the plug in the ungrounded GFCI.

Everything worked fine until I realized that when I touched the stainless steel mixing bowl and the stainless steel kitchen sink at the same time, I felt a very small shock. It was barely noticeable but most definitely there.

Is there something wrong with the mixer? Shouldn't the grounding problem have triggered the GFCI?

Live and learn...

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Old 12-15-2008, 01:49 PM   #2
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a very small shock.
1 mA is barely detectible, 10 mA is painful, GFIs trip at 4 mA.

Your appliance doesn't seem to be grounded and does seem to have leakage current to ground, and your sink is grounded.

In the situation above, if you replace your body in this circuit with an incandescent lamp, and the lamp lights, you might have avoided being killed, this time.

Even if it doesn't light it's possible your appliance is defective
or has a noise filter inside of it that depends on a ground connection. It's plausible that appliances with motors (that have commutators) inside would nowadays have noise filters.

If you have a multimeter you can use it to narrow down these symptoms to a cause or causes.


Last edited by Yoyizit; 12-15-2008 at 01:57 PM.
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Old 12-15-2008, 03:11 PM   #3
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Shocking kitchen appliance


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1 mA is barely detectible, 10 mA is painful, GFIs trip at 4 mA.

Your appliance doesn't seem to be grounded and does seem to have leakage current to ground, and your sink is grounded.

In the situation above, if you replace your body in this circuit with an incandescent lamp, and the lamp lights, you might have avoided being killed, this time.

Even if it doesn't light it's possible your appliance is defective
or has a noise filter inside of it that depends on a ground connection. It's plausible that appliances with motors (that have commutators) inside would nowadays have noise filters.

If you have a multimeter you can use it to narrow down these symptoms to a cause or causes.
Could there be voltage on his ground, either from the outlet being mis wired or something else in the house back feeding into the ground that caused the grounded appliance to become energized?

Would a GFCI have any way of telling if the ground is energized? It just looks to the hot and neutral for an unbalance correct?

Jamie
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Old 12-15-2008, 03:25 PM   #4
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Shocking kitchen appliance


you said the GFCI is ungrounded so how would you be getting a feedback from some other source?

and yes to your question about the GFCI and hot/neutral balance.
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Old 12-15-2008, 03:37 PM   #5
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you said the GFCI is ungrounded so how would you be getting a feedback from some other source?

and yes to your question about the GFCI and hot/neutral balance.

I was thinking mainly of where his 12-2 with cable junctions to the rest of the home power, if the ground was energized at that junction, or if a current carrying conductor some how got connected to his ground terminal on the outlet.
Thanks
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Old 12-15-2008, 04:17 PM   #6
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Could there be voltage on his ground, either from the outlet being mis wired or something else in the house back feeding into the ground that caused the grounded appliance to become energized?

Would a GFCI have any way of telling if the ground is energized? It just looks to the hot and neutral for an unbalance correct?

Jamie
No ground on the circuit.
Sink is fer sure grounded.
GFIs don't "know" ground (see page 6, below).
http://www.national.com/ds/LM/LM1851.pdf

I suppose some fault could cause the ground to be energized, but how exactly would this happen? It might be necessary to have more than one defect present for this to happen. Is it likely?

If the sink were somehow energized, the appliance neutral along with leakage current could cause this, but that seems very unlikely.

BTW, if this leakage current is caused by an onboard RFI filter, then enough of these perfectly good appliances on the same perfectly good GFI circuit will trip it.

Last edited by Yoyizit; 12-15-2008 at 04:22 PM.
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Old 12-15-2008, 05:23 PM   #7
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I was thinking mainly of where his 12-2 with cable junctions to the rest of the home power, if the ground was energized at that junction, or if a current carrying conductor some how got connected to his ground terminal on the outlet.
Thanks
Jamie
he said the GFCI was not grounded. I took that as there is no ground connected to the GFCI at all given the explanation. If there is no conductor tied to the ground terminal, there cannot be anything on the grounding terminal.

If there is a wire connected to the grounding terminal, then sure, there could be a backfeed from some other source. disconnecting it and running a short pigtail so it is accessable when the recep is installed but sans cover plate, check for voltage from the EGC to the sink. If there is voltage, it is from the appliance.If no voltage, check from the sink to a known good ground. If there is voltage there, there could be any of several problems.

warning; do not get into circuit with this grounding conductor at this point. You apparently have a problem and since there is current on the EGC and no idea as to why, it could be something great enough to cause injury or death.
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Old 12-15-2008, 05:55 PM   #8
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No ground on the circuit.

Maybe the person that posted this question could clarify how this is setup. He said: "...kitchen very soon. As it is, all of the wiring is 12 gauge (with ground) NM from the 1970's. Unfortunately, it's all tied to an older 15 amp circuit without a ground."

I took this to mean that he had his kitchen wired with 12 with ground, however it all ties into a 15a circuit somewhere, where there is no ground connection available.


I suppose some fault could cause the ground to be energized, but how exactly would this happen? It might be necessary to have more than one defect present for this to happen. Is it likely?

Very recently here (last night) a new poster had a question about a light switch, it was a 3 way and he was replacing it with a 2 way. He had a extra wire that he didn't know what to do with, so he connected it to the green (ground) screw. Assuming it was a metal box, that was bonded to the ground wire that came in on the romex or if it was EMT. Then the ground system becomes energized.

Jamie
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Old 12-15-2008, 06:02 PM   #9
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Shocking kitchen appliance


It sounds like that unattached EGC is picking up some induction and you can feel it when you connect from the mixer to the sink.

This is why you are not supposed to connect those "floating EGC's" to the grounding terminals of non-grounded circuits containing grounding devices.

Depending on the configuration of those GFCI's, you may or may not trip it out by connecting a jumper from the mixer bowl to the sink.
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Old 12-15-2008, 07:47 PM   #10
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I suppose some fault could cause the ground to be energized, but how exactly would this happen?


EDIT: Oh haha he meant like KitchenAid mixer. I thought he meant Audio Mixer like a DJ uses!!

Last edited by Gigs; 12-15-2008 at 08:10 PM.
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Old 12-15-2008, 11:26 PM   #11
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Shocking kitchen appliance


Just to keep an open mind here...

It is possible for your kitchen circuits to be inadvertently grounded and it is possible for your sink to not be grounded!

There could be something connected or plugged into your "ungrounded" kitchen circuit which is providing a ground (backwards grounded).

And a sink would typically be grounded via the plumbing, however sometimes metal pipes are replaced with plastic and a sink could be "floating" and not grounded. And what is actually leaking electricity could be something attached to the sink or its plumbing.

So the thing to do is verify that the sink is in fact grounded and that the outlet is not grounded. You can do this by running a long wire to an outside ground rod or a *known* good ground and using a multimeter.

Usually things are as they seem, but sometimes circumstances will surprise you!

I once saw a similar ungrounded circuit in an office addition. (Ground not attached at panel.) However the fluorescent ceiling lights were grounded to the new wiring and this was touching the metal drop ceiling, and a support for the drop ceiling was screwed into a grounded A/C vent! (Source of the ground.)
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Old 12-16-2008, 05:55 AM   #12
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yes the gfci shood have tripped yet doesnt always. could be many things. bad gfi...wired wrong gfi..."" non grounded service "" make sure service panel is grounded properly, water meter is jumpped out properly, and hot water hank is jumpped out. call me if u have ? 978-747-7314 THE E MAN
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Old 12-16-2008, 06:01 AM   #13
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. call me if u have ? 9---14 THE E MAN
It's better if he just posts here, so that if someone tells him something wrong, it'll usually get caught.
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Old 12-16-2008, 06:56 AM   #14
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Shocking kitchen appliance


Thanks for all the info.

To clarify:

The GFI receptacle is not grounded. The circuit is ungrounded and even though there is a ground wire present, it doesn't leave the sheath. The kitchen circuit is a branch of a run that consists of old 2 wire NM. Apparently, whoever wired the kitchen didn't bother to connect the grounds in any of the receptacles or boxes, because they wouldn't lead anywhere.

The sink in all likelihood is grounded. I don't know 100% but I've never seen any PVC pipes while in the crawl space.

The appliance in question is a metal Kitchen-Aid mixer (it weighs as much as a cinder block and looks identical to my grandma's 50 year old one).

I'm assuming the fault lies with the appliance. I'm not sure if there's anything I can do because the manual specifically says not to operate it in a receptacle w/no ground present...
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Old 12-16-2008, 07:11 AM   #15
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Does The Plug Have A 3 Or 2 Prongs On It

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