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Old 03-22-2012, 04:22 PM   #1
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GFCI blowing

Hi,
I have 67 Caravel I refurbished recently. One of the things I did was run a 3 foot length of 14-2 with ground from the outlet over the sink (where I installed a GFCI) down to feed the 110v ac for the propane/electric refrigerator. It was working fine and then we noticed the GFCI started breaking. The other day I noticed that the refrigerator had been left on electric and I turned it off. After resetting the GFCI I noted that it did not blow. So, somehow the refer is causing the GFCI to blow?? What would cause this? A fault in the refrigerator??

I opened up the back of the unit and checked the wires into the refrigerator and they are all fine. Does the refrigerator need to be grounded other than the ground wire that is connected to it?

Any other ideas would be appreciated?

Thanks
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Old 03-22-2012, 04:51 PM   #2
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It is possible that there is current leakage to ground in the electrical element. That's not unusual. You can check it with an ohmmeter by disconnecting both wires from the element and measuring between ground and one of the terminals on the element. Should be well over 20k ohms. If not, replace the element.
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Old 03-22-2012, 08:16 PM   #3
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Just a few thoughts - none of which may have anything to do with the GFI tripping. You mentioned you fed 14 gauge wire off the line side of the GFI. If your trailer is like ours it's wired with 12 gauge on 20 amp breakers. You should not go from a larger gauge wire to a smaller gauge. The opposite, while not "clean" wiring, is acceptable. Presuming 12 gauge/20 amp incoming, you should use a 20 amp rated GFI if you are not.

Regarding the tripping. It takes very little to trip a GFI and that's a good thing - except when connected to something like a refrigerator, freezer or sump pump. It's something like .008 amps. I'd never have these devices connected to a GFI due to nuisance tripping. Code allows exceptions for some appliances and when the outlet is not readily accessible such as an outlet behind your fridge.

You could still feed your fridge off the line to the GFI if you need to. Connect your 12 gauge wire going to the fridge outlet and a set of 12 gauge pigtails to the incoming 12 gauge power. Connect the pigtails to the LINE connections on the GFI. Your fridge outlet is then off the GFI and your GFI for the counter top still provides the protection you wanted.

Just a personal thing - whenever I connect three 12 gauge wires under one wire nut I usually twist the connection and then solder it if there's enough room to work. Probably a little over kill. You could also twist them well and use a red or larger wire nut.
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Old 03-22-2012, 08:52 PM   #4
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Quote:
You mentioned you fed 14 gauge wire off the line side of the GFI.
On edit - this should say LOAD not Line.
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Old 03-23-2012, 07:15 AM   #5
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Speaking about GFCIs in general, and apologies to anyone who already knows this stuff…

Certain appliances should not be plugged into a GFCI circuit because they can register as a ground fault even when there is no fault in the wiring:
1 - resistance heaters, such as the heating element in a coffeemaker or blow dryer;
2 - fluorescent lights that use a ballast to start;
3 - Any appliance that has a motor that starts and stops automatically, like a refrigerator or air conditioner compressor motor;
4 - Anything that has an electromagnetic solenoid switch;
5 - Any appliance that has its own built-in GFCI. The rule of thumb is to have only one GFCI on any one circuit.
There are valid engineering reasons why each of the appliance types listed above register as ground faults even if they're not faulty, but I won't bore you with technical details this time. The normal solution in all cases is to plug the non-GFCI-friendly appliances into a separate non-GFCI circuit— after you verify that it's not a real ground fault!
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Old 03-23-2012, 07:40 AM   #6
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Thanks for the responses

So, this may be as simple as the refrigerator shouldn't be on the GFI. I understand that. Getting it isolated in the box above and behind the sink is difficult as there's no extra room in the box for wires to be pigtailed with red wire nuts.

When I first installed this refrigerator about a year ago everything seemed to work ok without the GFI tripping. This summer I took the trailer to have a new AC installed. The fellow who did the install called me and said the GFCI was tripping?? The AC is a separate circuit and it already existed in the trailer going to an old Armstrong unit. I wondered at the time if there was anything he could have done, but he said he did nothing but hood up to the old wiring.

So far, I guess, I want to 1.) unhook my wiring to the refrigerator and plug it in with a non GFCI source and just make sure my refrigerator is working properly. 2.) check the refrigerator to see i there is some current leaking somewhere? Not exactly sure how to do this if someone could explain in detail. 3.) If the refrigerator run with non GFCI source then perhaps I've got to refeed the refrigerator another way as someone suggested, or perhaps run a separate wire from the panel.

By the way my Caravel has two 15 amp breakers and #12 Aluminum wire. The #14 wire I ran to the refrigerator is not to an outlet behind the refrigerator, but wires directly into the back of the refrigerator.

Thanks for all your help, Everyone.
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Old 03-23-2012, 07:52 AM   #7
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If you're mixing aluminum and copper wiring, you do need to ensure that the connectors you use, and the GFCI outlet in this case, are rated for both aluminum and copper. You can't just twist a copper and aluminum wire together and use a normal wire nut on the connection. It'll fail, as the copper and aluminum expand at different rates as they heat up.

Chris
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Old 03-23-2012, 09:24 AM   #8
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Quote:
Originally Posted by vonzellen View Post
So, this may be as simple as the refrigerator shouldn't be on the GFI. I understand that. Getting it isolated in the box above and behind the sink is difficult as there's no extra room in the box for wires to be pigtailed with red wire nuts.

When I first installed this refrigerator about a year ago everything seemed to work ok without the GFI tripping. This summer I took the trailer to have a new AC installed. The fellow who did the install called me and said the GFCI was tripping?? The AC is a separate circuit and it already existed in the trailer going to an old Armstrong unit. I wondered at the time if there was anything he could have done, but he said he did nothing but hood up to the old wiring.

So far, I guess, I want to 1.) unhook my wiring to the refrigerator and plug it in with a non GFCI source and just make sure my refrigerator is working properly. 2.) check the refrigerator to see i there is some current leaking somewhere? Not exactly sure how to do this if someone could explain in detail. 3.) If the refrigerator run with non GFCI source then perhaps I've got to refeed the refrigerator another way as someone suggested, or perhaps run a separate wire from the panel.

By the way my Caravel has two 15 amp breakers and #12 Aluminum wire. The #14 wire I ran to the refrigerator is not to an outlet behind the refrigerator, but wires directly into the back of the refrigerator.

Thanks for all your help, Everyone.
With aluminum wire nothing about pigtailing mentioned above now applies.
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Old 03-23-2012, 01:08 PM   #9
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Very few GFCI are rated for use with aluminum wire; shop carefully. Aluminum wire has a higher resistance than copper wire of the same gauge, and so generates more heat— one reason why many municipalities forbid its use in new home construction. When making a transition from copper to alunimum, or vice versa, the copper conductor should be one size smaller than the aluminum wire (12-gauge aluminum to 14-gauge copper, for example) to ensure that both sides have similar resistance.

When making your connections, don't use splices and wire nuts; use a terminal block, and coat any bare aluminum wire with dielectric grease when you're done to help retard oxidation. A plus to this method is that it's easier to connect three wires at a terminal block for a branch circuit. A terminal block also does not require soldered connections like a proper splice. When buying the terminal blocks, be sure to mention that you are connecting aluminum wire to copper wire so you get the right type. As with GFCI, not all terminal blocks are rated for aluminum wire.
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Old 03-23-2012, 02:46 PM   #10
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vonzellen

As others have said you don't want a fridge to be plugged into a receptacle protected by another gfci receptacle. To wire the gfci receptacle so that it protects only that receptacle and not the next (fridge) receptacle down stream, connect the inlet wiring to the line terminals and also the outlet wiring to the same line terminals. Nothing should be connected to the load terminals. After you have done this trip the gfci receptacle and verify with a voltage tester that the fridge receptacle is still hot.

Dan
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Old 03-23-2012, 05:38 PM   #11
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I'm currently posting from mobile, so I can't link the thread, but there was a similar thread on this which I myself inquired on. My fridge was all of a sudden blowing the gfi on my house where the airstream was plugged in to. This never happened in previous years. I traced the problem to the fridge. I replaced the heating element on the fridge ($50 with shipping) and no more blowing of the gfi.
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Old 03-23-2012, 09:12 PM   #12
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Quote:
Originally Posted by Protagonist View Post
Speaking about GFCIs in general, and apologies to anyone who already knows this stuff…

Certain appliances should not be plugged into a GFCI circuit because they can register as a ground fault even when there is no fault in the wiring:
1 - resistance heaters, such as the heating element in a coffeemaker or blow dryer;
2 - fluorescent lights that use a ballast to start;
3 - Any appliance that has a motor that starts and stops automatically, like a refrigerator or air conditioner compressor motor;
4 - Anything that has an electromagnetic solenoid switch;
5 - Any appliance that has its own built-in GFCI. The rule of thumb is to have only one GFCI on any one circuit.
There are valid engineering reasons why each of the appliance types listed above register as ground faults even if they're not faulty, but I won't bore you with technical details this time. The normal solution in all cases is to plug the non-GFCI-friendly appliances into a separate non-GFCI circuit— after you verify that it's not a real ground fault!
I haven't heard that before and am not sure I believe very much of it. Could you supply an authoritative source for this lengthy list?

Quote:
Originally Posted by vonzellen View Post
When I first installed this refrigerator about a year ago everything seemed to work ok without the GFI tripping. This summer I took the trailer to have a new AC installed. The fellow who did the install called me and said the GFCI was tripping?? The AC is a separate circuit and it already existed in the trailer going to an old Armstrong unit. I wondered at the time if there was anything he could have done, but he said he did nothing but hood up to the old wiring.
Leakage is cumulative so if you have an old air conditioner that leaks maybe 4 mA and doesn't quite trip the GFCI, and you have a fridge element that leaks maybe 4 mA and doesn't quite trip the GFCI by itself, it's possible that they will trip it when both appliances are plugged in.

There's an article on "ghost trips" here that explains this in more detail:

Chasing



Quote:
Originally Posted by vonzellen View Post

So far, I guess, I want to 1.) unhook my wiring to the refrigerator and plug it in with a non GFCI source and just make sure my refrigerator is working properly. 2.) check the refrigerator to see i there is some current leaking somewhere? Not exactly sure how to do this if someone could explain in detail. 3.) If the refrigerator run with non GFCI source then perhaps I've got to refeed the refrigerator another way as someone suggested, or perhaps run a separate wire from the panel.
You might find that it's easier and cheaper to just replace the heating element on the fridge and see if that clears up the problem.

Quote:

By the way my Caravel has two 15 amp breakers and #12 Aluminum wire. The #14 wire I ran to the refrigerator is not to an outlet behind the refrigerator, but wires directly into the back of the refrigerator.
Please heed the cautions others have shared regarding aluminum wire.

You might be better off using a GFCI circuit breaker so you don't have to figure out a way to get aluminum wire hooked up to a GFCI outlet properly, given the limited space you have available.
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Old 03-24-2012, 06:36 AM   #13
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Quote:
Originally Posted by WineStream View Post
I'm currently posting from mobile, so I can't link the thread, but there was a similar thread on this which I myself inquired on. My fridge was all of a sudden blowing the gfi on my house where the airstream was plugged in to. This never happened in previous years. I traced the problem to the fridge. I replaced the heating element on the fridge ($50 with shipping) and no more blowing of the gfi.
Link to similar thread that helped me: http://www.airforums.com/forums/f37/...ker-87863.html
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Old 03-24-2012, 12:25 PM   #14
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Quote:
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I haven't heard that before and am not sure I believe very much of it. Could you supply an authoritative source for this lengthy list?
You're not obligated to believe a single word of it; that's the great thing about advice. And for that matter, I don't much care if you believe me. If we all agreed with each other all the time, the world would be a very boring place.

I have accumulated my information over a long career as an engineer (college degree as a civil engineer, crossed over to mechanical engineering later), working side-by-side with electrical engineers, electricians, and general contractors. Every single item on my list has been a source of actual "nuissance tripping" on at least one project I've worked on in my 31-year career.

If you want to go to your local library and find sources, start with the National Electrical Code. Cross-reference the National Electrical Safety Code. If you want to get your information in easily digestible factoids from the Internet, you can Google "GFCI nuissance tripping." Or you can go to college and take some electrical courses.

Or you can blow off my advice and do it your own way. Whatever makes you happy.
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