A GFI Outlet Problem FAQ

Does the GFI test trip OK with its pushbutton ? Does the GFI test OK with a plug-in tester ? Have you tried a different extension cord ? John T.

I experienced the same type of problem with a ceiling fan I have in a bedroom. It does not trip the GFI every time it is turned off, but often does. I searched the Internet and found others with the same experience. I believe it is the inductive spike caused by the fan windings that is tripping the GFI.

while probably has nothing to do with the GFI tripping that 16 gauge cord seems light for a heater. If like most heaters it should have atleast a 14 gauge wire going to it.

Things with motors in them will often trip a GFI due to the inductance of the motor. It depends on when the switch is turned off in the AC cycle.

What is the wattage of the space heater? Putting it on a cord is a bad idea, anything over 10A on 16 GA is a dumb idea. NONE of the wire should be warm.

Keep a phone handy and put 911 on speed dial.

It operates ok when pushed into On or Off.

I don't know what kind of test you are reffering to. I used a volt meter and it shows 120 v when GFI is On, and 0 v when GFI is off with it's button outward.

Nope. What baffles me is if it is because the cord is not large enough for the amount of current being used, why is it that only the plug and the first inches or so or of the extension cord wire are kind of warm to the touch? I'd expect much more of the wire to be overly warm.

That's a bummer. I read a web site by a Fire Chief that said fan fires inside the ceiling were the most destructive and hardest to contain by fire fighters.

I agree. I'm going to start checking around for a heavier gauge extension cord.

The GFI even clicks off when I turn the Heat switch Off and wait a number of seconds before I turn off the fan itself. Even with the Heating element set to Off, the tripping will still happen when I afterwards turn off the fan blade.

The fan blade has the On/Off feature so when the heater is set to Auto, the fan can be allowed to run or not while the heating element is off.

These testers are quite common - this is just one example :

The plug end of the cord gets warm because there is resistance at the junction between the blade and the wire conductor. Throw that cord away and do not ever use it again. Whether it solves your GCI problem or not, the cord needs to be retired with prejudice.

An inductive voltage spike is a high-voltage, low-current thing, like a spark plug sparking. The GFI works on current ground faults, or current imbalance, not voltage. It's hard to see it causing the 5 mA hot-neutral current imbalance so it must be causing current to flow to ground.

Maybe a cheap surge suppressor like you use for a computer would solve his problem.

I'll assume that you have at least 1 GFI receptacle in your kitchen. Take the heater into the kitchen, plug it directly into the GFI receptacle, let it run for as long as it ran in the bathroom when the extension cord plug became hot, and then cycle the heater a few times. If the kitchen GFI trips off, the problem is being caused by the heater. If the GFI doesn't trip, try attaching the same extension cord in the kitchen you were using in the bathroom and let the heater run long enough so that the plug of the extension cord gets as hot as it did in the bathroom. Then cycle the heater a few times. If the GFI still doesn't trip, the problem is probably the bathroom GFI. If it does trip, the problem is likely to be the under-rated or bad extension cord

If it's the bathroom GFI, you might just have a loose connection between one of the wires and the GFI terminal that wire connects to. A loose connection will cause heat and the wire may move just enough to create a momentary surge and trip the GFI. You already said the extension cord plug gets hot. Some of that heat may be heating the GFI in addition to heating the plug and adjacent part of the extension cord wire. Turn off the circuit breaker supplying the bathroom GFI. Take out the GFI mounting screws and pull the GFI with attached wires out of the wall far enough to examine where the wires attach to it. Even if the wires seem secure, try tightening the screws holding the wires to the terminal. If the screws don't turn at all, your wires weren't lose. If any of the screws turn, after tightening, reinstall the GFI into the wall, turn on the circuit breaker, and see if the GFI trips as before. If not, you found and solved the problem. If the GFI still trips, make sure to once again turn off the correct circuit breaker, disconnect the GFI, and take it to your local hardware store. Get a replacement GFI with the same specs and install it making sure to connect all the wires to the correct terminals. That should fix the problem.

I'm am going to dump the cord.

Thanks.

I'm going to get a larger gauge extension cord and buy a checker someone sent me a url for. I never knew this type of checker existed.

Thanks. I'm going to get one of them.

I never knew such a thing existed.

That tester will tell if the GFCI is providing protection but it will NOT tell you if it is overly sensitive or "nuisance tripping"

The 'protection' part is the important part I worry about, not so much the 'nuisance tripping'.

To heck with it. I'm going to get that meter and check what it says about the wiring, etc., then I'm going to have the GFI replaced.

What I don't understand is why the GFI trips off when I turn the heater fan off but not when I turn the unit on.

I turn off the heating element first, and then I wait a few seconds before turning off the fan. That's when it trips. I don't get why it trips when it's only the fan that was still running. That's not a current overload.

Yes, exactly. At least that's one big possibility

That seems rather wasteful. You can cut the plug off the end of the cord and connect a new plug, and use it for other things. BUT, maybe that's not the problem at all. One should also consider the connection between the plug and the receptacle. It could be the prongs of the plug, or it could be the receptacle. IIRC, I've not had any luck bending one of the prongs to make it push harder against the receptacle. OTOH, if the plug's prongs are each folded back, so they are two layers, you can carefully pry them apart and make them wider. I think that has helped in a couple occasions. But the most serious time was when the receptacle was 40 years old and loose**. Regardless of the age, the receptacle could have lost its springiness and its ability to squeeze the prongs of the plug. **In that case, the hard rubber plug on the heater got so hot that it had flames coming from it, 1 or 2" high. They died out quickly when I pulled the cord out of the wall.

I'd try a different extension cord to see if the problem follows the cord, or stays with the receptacle. Or don't use an extension for a while. How big is your bathroom you that the heater has to be closer to the tub than the heater's own cord permits.

It measures the current going out on the hot wire and comming back on the neutral wire. If there is more than a very small difference the GFI will trip, something less than .01 amp. Say if you put your fingers in the hot and neutral wires it will not trip but if you put your fingers in the hot and ground pin it will trip hopefully fast enough not to hirt you very much or kill you.

Devices with motors or other coils of wire in them can case problems. When the switch is cut off the electric field of the motor will generate a current. If it is very much then the GFI will trip.

I lost track, is this at the main breaker box or at the outlet ?

If an outlet it does not protect a current overload but will if in the breaker box.

The heater is plugged into a GFI mounted on the bathroom wall.

I'm really through with this matter. I'm going to use the cures I mentioned earlier - bigger extension cord, check for a bad ground, and then get a new one installed once I'm sure it ain't the house wiring.

Enuf is enuf with the headaches. : o)