What might cause GFCI outlet problems?

In: Home Electricity, Electrical Troubleshooting, Recreational Vehicles (RVs) [Edit categories]

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Answer:

Answer for USA, Canada and countries running a 60 Hz power supply service.

The device could be faulty and it could also be working perfectly, as they typically do. You could receive a life threatening shock. GFCI's are extremely sensitive and most likely you have plugged in a piece of equipment that should be thrown away.

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Sounds like you tripped the circuit breaker. Microwave ovens use a lot of current and can cause this. The microwave could also be faulty. You should have the microwave either plugged into a 20 amp circuit or a dedicated (only feeding the microwave) 15 amp circuit. If the microwave has been on this outlet for a while it may have worn out the mechanism by tripping it frequently.

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1. you suggest your microwave made a loud noise - try it in another outlet that works - maybe it is no good and tripped the breaker, as suggested before. If it trips the new breaker, get a new microwave.

2. if the breaker is tripped, then the GFCI may not reset [depends on how old a model it is] and it won't test with the power out. If the breaker resets, you may find the GFCIs work. [The second outlet doesn't work because it is connected to the load terminals of the GFCI.]

3. if the breaker resets and the GFCI still won't work, you may have damaged the GFCI when the microwave failed. Have the GFCI replaced. 4. I suggest you probably should call an electrician.

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The Capacitor on a single phase motor (for a "fan", etc.) sometimes causes a GFCI to trip. Commercial Grade GFCIs are better suited to this application.   

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Two other things can cause false tripping:

1. A noise filter or surge protector in the circuit after the GFCI bypasses high frequency noise to ground. This unbalances the current in the hot and neutral, tripping the device.

2. Dirt or insects inside the outlet box. One time I opened an outlet box that was tripping the GFCI even with no plug in the socket. The box was full of dead roaches. I removed the bugs, and the device started working normally. 

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GFCI circuit breakers perform two functions. If it is a true circuit breaker it will prevent "over-current" conditions from overheating the wiring of your home and hopefully minimize the potential for fire. All circuit breakers and fuses are designed to 'trip' or 'blow' when an over-current condition exists. GFCI circuits have an additional function. To prevent or minimize the potential for hazardous shocks, GFCI circuits compare the current that goes across the two wires that make up the hot and common voltage lines of an outlet. If the current on the two wires does not match precisely, the assumption is that current is being lost to something outside of the circuit. This condition is called a "ground fault". In simple terms, it means that there is high potential that YOU are grounded, as in standing in a puddle of water, and YOU have touched the "hot" side of the circuit or the device somehow allows current to go outside of the normal voltage path. A ground fault can exist if an outside outlet has become wet with rainwater, or an outside extension cord is laying in water or an appliance is in the process of failing and voltage leaks to the ground wire. But as already mentioned, it can also indicate that the GFCI has failed, although that doesn't often happen.

G.F.C.I. [Ground Fault Circuit Interrupter] trips when it senses a ground fault. In a correctly wired circuit the return path should be on the neutral wire. The circuit will trip if the GFCI senses a difference in the current (Amps) in the Black "hot wire" from what is returning in the White "neutral wire". These two values should be the same unless you are leaking electricity which is called a ground fault. This can happen in a wet location when electricity is using the water as it's ground and not returning back through the neutral wire. Older motors can also leak electricity in to their motor housings. If the electricity is not returning through it's designed path then you may have a safety hazard and your GFCI is protecting you.

To test a tripping GFCI follow these steps.

1. Remove every appliance connected to the GFCI's circuit and reset it. If it doesn't reset there may either be a wiring fault behind a socket outlet or your GFCI itself has become faulty.

2. Make sure what ever you are plugging in to the GFCI is dry and not damaged.

3. Only plug in one item at a time. If you are plugging in a defective item it will cause the GFCI to trip and that item should be replaced.

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From what this question is saying, the TEST button is doing its job - it is testing ( = checking) that the GFCI is working correctly!

After you have tested the device by pressing the TEST button you should be able to press the RESET button again - and DO NOT PRESS THE TEST button again - and everything should work.

Either your GFCI is bad [in which case replace it] or it is working perfectly.

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It is probably working. My sister had a similar problem. She just kept resetting until it held, but every time she got in her hot tub she got shocked.
Luckily she wasn't killed. It turned out to be the fly weights shorting out against the capacitor wires, turning the water into the hot leg. Don't mess around with this kind of problem.

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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.