Norcold 1200 throwing GFCI

[bpu699]

I’ve read lots of threads on this, and reviewed the manual...

Just trying to make sure this isn’t “normal” with a 100ft extension cord...

Running the fridge on AC, runs for 30minutes then throws the GFCI...

Checked both heating rods, resistance 60-100 or so... neither touched to ground shows continuity...

This fridge has 2 heating rods...

If I leave either connected, runs indefinitely... plug in both, throws the GfCI...

Now, I’m running this off a 15 amp grounded house outlet, on a 100ft extension cord...

Propane works fine.

Haven’t had a chance to try it on a 50 amp pedestal...

(I had another thread about some voltage to the RV skin with an extension cord that lacked a ground and appears to be due to reverse polarity - since fixed with no issues. I wonder if the two have/had something to do with each other)...

[jimknoll]

My 1200 runs on a 15A circuit, but I don't know if it has 1 element, or 2. If you aren't headed to a 50A hookup soon, can you try to run the generator, instead of the 15A chord?

[amosnandy]

Originally Posted by bpu699

I’ve read lots of threads on this, and reviewed the manual...

Just trying to make sure this isn’t “normal” with a 100ft extension cord...

Running the fridge on AC, runs for 30minutes then throws the GFCI...

Checked both heating rods, resistance 60-100 or so... neither touched to ground shows continuity...

This fridge has 2 heating rods...

If I leave either connected, runs indefinitely... plug in both, throws the GfCI...

Now, I’m running this off a 15 amp grounded house outlet, on a 100ft extension cord...

Propane works fine.

Haven’t had a chance to try it on a 50 amp pedestal...

(I had another thread about some voltage to the RV skin with an extension cord that lacked a ground and appears to be due to reverse polarity - since fixed with no issues. I wonder if the two have/had something to do with each other)...

Motorhomes do not like being plugged into GFCI. It has something to do with failure to recognize the ground when on rubber tires. I suspect the ground fault is very minor, hence you can run one at a time but when you run both it doubles and thats just enough to trip the GFCI,

Is it running fin now on a no GFCI outlet. Have you checked all three lines for current draw. Line, Neutral and Ground?

[amosnandy]

Originally Posted by jimknoll

My 1200 runs on a 15A circuit, but I don't know if it has 1 element, or 2. If you aren't headed to a 50A hookup soon, can you try to run the generator, instead of the 15A chord?

A Norcold 1200 draws about 450 watts on 120v. So overloading isn't his problem.

[Ray,IN]

Originally Posted by bpu699

I’ve read lots of threads on this, and reviewed the manual...

Just trying to make sure this isn’t “normal” with a 100ft extension cord...

Running the fridge on AC, runs for 30minutes then throws the GFCI...

Checked both heating rods, resistance 60-100 or so... neither touched to ground shows continuity...

This fridge has 2 heating rods...

If I leave either connected, runs indefinitely... plug in both, throws the GfCI...

Now, I’m running this off a 15 amp grounded house outlet, on a 100ft extension cord...

Propane works fine.

Haven’t had a chance to try it on a 50 amp pedestal...

(I had another thread about some voltage to the RV skin with an extension cord that lacked a ground and appears to be due to reverse polarity - since fixed with no issues. I wonder if the two have/had something to do with each other)...

Did you ohm out the elements while they are installed?



I suspect a bad heating element, a good one should read 64 ohms. The Norcold 12xx has two 225W heating elements. What else is on that 15A circuit? I suspect you have overloaded that 15A circuit and after 30 minutes it trips the gfci due to overheating the wiring which then leaks current.

reference: http://bryantrv.com/docs2/docs/ncold1200.pdf


EDIT: to safely use a 100' extension cord for 15A, it must be AWG 8 wire size.

[twinboat]

It will work on 50 amp because there is no GFCI on them. No GFCI, no trip.

Its not to much current because GFCIs look for lost current, not overloads. That's the circuit breakers job.

So now we still have some leakage between neutral and ground.

Both heaters may be leaking a small amount of current but not enough to trip the GFCI.
If both are hooked up, the leakage between the two is enough to trip the GFCI.

Take each element and with an ohm meter probe the shell and each wire. You should have no reading, there should be no conductivity to the outer shell.

[Gary RVRoamer]

A amp overload won't trip a GFCI, which is a different condition altogether. A million amp over load won't cause a GFCI trip, but as little as 0.006 amps shorted to ground will.

Motorhomes do not like being plugged into GFCI. It has something to do with failure to recognize the ground when on rubber tires.

It has nothing to do with tires and a properly wired RV won't trip a GFCI circuit. Ever. Nor does it have anything t do with the length of the extension cord. It may be that both heat elements have very high resistance shorts to ground so that it takes two of them to yield the 6 milli-amps needed to trip the GFCI, but that seems far-fetched. Or that it takes 30 minutes to do that.


There won't be a GFCI on the 50A pedestal, so no trip is possible.

[bpu699]

Originally Posted by twinboat

It will work on 50 amp because there is no GFCI on them. No GFCI, no trip.

Its not to much current because GFCIs look for lost current, not overloads. That's the circuit breakers job.

So now we still have some leakage between neutral and ground.

Both heaters may be leaking a small amount of current but not enough to trip the GFCI.
If both are hooked up, the leakage between the two is enough to trip the GFCI.

Take each element and with an ohm meter probe the shell and each wire. You should have no reading, there should be no conductivity to the outer shell.

I took each wire, yellow and black, to ground (frame) and there was no conductivity... I didn’t touch it to the casing, as it seems pretty unreachable...

[bpu699]

Originally Posted by Ray,IN

Did you ohm out the elements while they are installed?



I suspect a bad heating element, a good one should read 64 ohms. The Norcold 12xx has two 225W heating elements. What else is on that 15A circuit? I suspect you have overloaded that 15A circuit and after 30 minutes it trips the gfci due to overheating the wiring which then leaks current.

reference: http://bryantrv.com/docs2/docs/ncold1200.pdf


EDIT: to safely use a 100' extension cord for 15A, it must be AWG 8 wire size.

One read 60, one read 100 ohms... manual says normal is 70 ohms or so...

Not sure if these heating elements are removable through the access port outside? It looks super tight...

[bpu699]

Originally Posted by jimknoll

My 1200 runs on a 15A circuit, but I don't know if it has 1 element, or 2. If you aren't headed to a 50A hookup soon, can you try to run the generator, instead of the 15A chord?

Prior owner had no issues using it... but then again he only used it at camp grounds, not on a house gfci...

I sometimes wonder if I spend too much time worrying about stuff.... that isn’t a problem....

My first trip is wendsday, just wanted to cool the fridge down for a couple days first....

[bpu699]

Originally Posted by Gary RVRoamer

A amp overload won't trip a GFCI, which is a different condition altogether. A million amp over load won't cause a GFCI trip, but as little as 0.006 amps shorted to ground will.



It has nothing to do with tires and a properly wired RV won't trip a GFCI circuit. Ever. Nor does it have anything t do with the length of the extension cord. It may be that both heat elements have very high resistance shorts to ground so that it takes two of them to yield the 6 milli-amps needed to trip the GFCI, but that seems far-fetched. Or that it takes 30 minutes to do that.


There won't be a GFCI on the 50A pedestal, so no trip is possible.

I bypassed the RV wiring, plugged the fridge directly to the cord, same result. So the RV wiring has nothing to do with it I suspect, unless it’s some leakage on the 12 volt circuit....

Any harm running the fridge on one heater core plugged in at home? Cooled the freezer down with no issues...

Fridge portion was pretty much the same temp after 6 hours though...

I would be happy to change both heaters if it would make a difference...

[Old-Biscuit]

One element will NOT cool fridge ....need both to properly heat the ammonia

That 100ohmed element is suspect

Hard to remove/replace via lower vent cover as access is very limited
Usually have to unscrew fridge and slide in out of campartment partially to get to them
When replacing.replace BOTH at same time

15A GFCI outlet on a 100' small gauge extension cord (doubt you have a heavy gauge).....lucky to run charger for maintaining batteries

[Ray,IN]

Originally Posted by bpu699

One read 60, one read 100 ohms... manual says normal is 70 ohms or so...

Not sure if these heating elements are removable through the access port outside? It looks super tight...

Nope, the manual states 64ohms, it does not state a range only a specific number. It also states ACV must be between 108-132VAC at the fridge, did you measure that?
Again, reference: http://bryantrv.com/docs2/docs/ncold1200.pdf

[bpu699]

Originally Posted by Ray,IN

Nope, the manual states 64ohms, it does not state a range only a specific number. It also states ACV must be between 108-132VAC at the fridge, did you measure that?
Again, reference: http://bryantrv.com/docs2/docs/ncold1200.pdf

Voltage was correct...

What I may do is just buy both heater cores, plug them into the circuit and leave outside the fridge, and see if it sets off the gfci... if it doesn’t, then go through the effort of removing the fridge...