GFCI conundrum

bodbs · 10-10-2010, 12:18 PM

A GFCI in my kitchen tripped, and wouldn't reset. I isolated the problem to be an instant hot water heater under my sink. This is the only device plugged into that particular outlet. When I unplugged it, the GFCI could be reset. But when I plugged the water heater into another outlet on the same circuit, it did not trip. Additionally, when I plugged a different appliance into the outlet that the water heater was originally plugged into, the circuit did not trip. This water heater had been plugged into the same outlet continuously for 3 years with no problem.

Any idea what might cause the water heater to trip the GFCI when plugged into this particular outlet, but not when plugged into another outlet, and when this outlet does not trip with another appliance plugged into it?

TimPa · 10-10-2010, 01:00 PM

good troubleshooting so far. although you tried plugging the heater into another outlet "on the same ckt", it isn't clear if that receptacle is gfci protected or not. with power off, you may want to open it up and look to see if all the wires are intact, esp the heating coils.

AllanJ · 10-10-2010, 01:01 PM

1. Are you sure that the alternate outlet into which you plugged the heater was under the jurisdiction of the same GFCI?

2. There may have been an intermittent loose connection or fault such as in the cord or plug or outlet depending on the angle the cord was curled or bent.

bodbs · 10-10-2010, 01:38 PM

I appreciate your help and suggestions.

Yes, the second outlet is protected by the same GFCI. I pulled the heater out and opened it up to take a look, but all wires appear to be solidly intact. Also, it's unlikely that there are loose wires in the heater, since I have moved it back and forth between outlets several times, and the only time it trips the circuit is when it's plugged back into the original receptacle.

Would the next step be to replace the outlet under the sink, even though other electrical devices appear to work in it, and hope that fixes it?

frenchelectrican · 10-10-2010, 07:10 PM

Take the ohm meter and read the ground and netural ditto with ground and hot plug side and you will see the numbers there and the way you describing more likey the heating element is on the way to be history.

I have see it and it did happend to me twice before.

Merci.
Marc

bodbs · 10-12-2010, 03:53 PM

OK, I tested the appliance cord with a multimeter, and the ground + neutral and the ground + hot both read about 1800 when I have the range selector switch set to 200k. Unfortunately, I'm a neophyte when it comes to this stuff, and don't know how to interpret that.

frenchelectrican · 10-12-2010, 08:01 PM

If you going to read in Ohms scale make sure your tester probe is on the ohms fitting { some will do that by moving one plug on the tester } and set the Ohm scale at the lowest setting you can get and read it with instat waterheater undersink verison you should get about 40 to 50 Ohms range anything lower or higher then the element is done and useally most case the element is not a replaceable item on undersink instat waterheater.

Merci,
Marc

bodbs · 10-12-2010, 08:09 PM

Yes, I had it in the Ohm fitting. And I tried each of the lower settings, starting with the lowest. The reading never changed from "1" until I got to the highest setting. It sounds like what you are saying is that the readings I got indicated that the heater is toast. I'll go ahead and replace it.

Thanks for the help.

frenchelectrican · 10-12-2010, 08:12 PM

Quote:

Originally Posted by bodbs

Yes, I had it in the Ohm fitting. And I tried each of the lower settings, starting with the lowest. The reading never changed from "1" until I got to the highest setting. It sounds like what you are saying is that the readings I got indicated that the heater is toast. I'll go ahead and replace it.

Thanks for the help.

That is correct if you can not get any reading in low scale setting and did you try to hit the probes together to see if that drop down to zero or near zero { that what I always do that all the time before I do use the Ohm scale to make sure they are good reading }

Merci.
Marc

bodbs · 10-12-2010, 08:27 PM

When I connect the probes with the switch in the 2000K position, the 200k position, or the 20K position, I get a reading of 0. But in the 2K position, it reads 2, and in the 200 position, it reads 1.1. Shouldn't it read zero in all positions? Do I need to try a different multimeter? I thought the digital multimeters were self-correcting.

frenchelectrican · 10-12-2010, 08:31 PM

Quote:

Originally Posted by bodbs

When I connect the probes with the switch in the 2000K position, the 200k position, or the 20K position, I get a reading of 0. But in the 2K position, it reads 2, and in the 200 position, it reads 1.1. Shouldn't it read zero in all positions? Do I need to try a different multimeter? I thought the digital multimeters were self-correcting.

Not all the DVM are self correcting and most case they will get pretty close to the specs what the manufacter call and on low scale side expect a digit or two show up like yours I have done the same thing with my DVM that why I always use the standard AVM { Anlong volt meter } with real neddle pointer so I can able finetune as need to.

and test the instant tankless water heater on 200 Ohms postion and read the numbers on that and that will give you a answer on it.

As I mention above with good element you should have about 40 to 50 Ohms range. { basied on 1200 watt element on 120 volt set up }

Merci.
Marc

bodbs · 10-12-2010, 08:43 PM

OK. I wasn't sure if 1.1 or 2 were what you considered to be "close to zero", or if by "close to zero" you meant something more like 0.2. Now I understand. And yes, in the 200 Ohms position, the reading stays at 1 (and stays at 1 until the highest setting position).

Thank you Marc, for helping me definitively determine that I need a new heater, and that the problem is not with my house wiring or outlets.

frenchelectrican · 10-12-2010, 08:49 PM

Quote:

Originally Posted by bodbs

OK. I wasn't sure if 1.1 or 2 were what you considered to be "close to zero", or if by "close to zero" you meant something more like 0.2. Now I understand. And yes, in the 200 Ohms position, the reading stays at 1 (and stays at 1 until the highest setting position).

Thank you Marc, for helping me definitively determine that I need a new heater, and that the problem is not with my house wiring or outlets.

Now you can understand the basic function of the DVM and that help you to rule it out and the way you read it stay at "1" that means the element is open or allready fizted out { can shorted to the frame that cause the GFCI to trip }

And it is not a problemé at all that what we are here for.

Merci.
Marc