GFCI stands for Ground Fault Circuit Interrupters and it was designed by Charles Dalziel in 1961.

Mr. Dalziel apparently knew a thing or two about how much electricity it took to kill a person and developed a device designed to protect human lives. In contrast, circuit breakers were designed to protect equipment and buildings and operate completely differently.

Here’s a mini-lesson on electricity:

All electricity attempts to return to its original source. In other words, when an electrician refers to a circuit, he is talking about electricity leaving your panel, flowing through the insulated wires in your house to supply power to any energized items and then following a return path back to the panel. Circuit simply refers to a roughly circular route that starts and finishes at the same place…in this case, your electrical panel.

A GFCI outlet measures the power coming in and then returning to your panel as it completes the circuit. It was designed to detect any difference more than 4 or 5 milliamps and to react quickly (less than one-tenth of a second) to shut down any circuit out of this small range.

For reference, there are 1,000 milliamps in an amp. Any current over 1 milliamp can be felt, 5 milliamps will produce a painful shock, currents at 10-15 milliamps can paralyze or freeze muscles (making it impossible to release an energized object such as a tool, appliance or wire) and currents as low as 50-100 milliamps can be fatal. If a person is accidentally exposed to electricity, it is very important to stop the flow of electricity into the body as fast as possible.

When a GFCI “trips” it is working as designed. If the GFCI’s internal current transformer senses more than a 4-5 milliamp loss, it instantly shuts down the outlet and any outlets it feeds to prevent accidental electrocution. Most often, when a GFCI “trips” it is the result of a faulty appliance plugged into the outlet or an outlet down circuit. Before calling an electrician, you may want to try this simple diagnosis: Unplug all appliances plugged into or down circuit from the GFCI, reset your GFCI by pushing the button in the center of the outlet and then plug the appliances back into the GFCI one at a time and turn them on to see if any of the appliances are causing the appliance to “trip”. If you plug in your coffee maker and the GFCI immediately trips, it is likely you have a faulty appliance and the GFCI is operating as designed.

All man-made objects have a lifespan and eventually wear out. It is recommended that all GFCI’s should be tested monthly to ensure they are operating correctly. Simply push the TEST button to turn power off to the circuit which should cause the RESET button to pop up. You will need to hit RESET to turn the GFCI back on. Do not assume that because an outlet is working that the GFCI protection is in effect. Newer GFCI outlets have an interlock to prevent the outlet from working if the GFCI protection fails however older GFCI outlets do not have this built-in failsafe.

GFCI outlets should be installed in any area where moisture can be potentially present, examples include kitchen countertop outlets, bathroom outlets, all exterior outlets and garages. Your electrician may suggest additional areas where GFCI protection is recommended or required by the National Electrical Code.

What Causes Ground Fault Circuit Interrupter to Trip?
Here are five reasons your GFCI outlet keeps tripping and what you should do.

1. Ground Fault Occurrence
Ground faults occur when the hot wire or live wire comes into contact with the ground wire or the grounded area of an appliance. Usually, GFCIs function by detecting when the current is flowing along an unintended path (e.g. through water or a person).

The instant GFCI detects there is even the slightest of current leakage as low as 0.005 Amps, it trips right away.

How do you determine if the current is leaking? Unplug everything on that circuit and make sure all the switches are off. Check for any wear that may have occurred to the equipment. Any slight damage means the electrical part is no longer protected from the contact.

2. Moisture in the Receptacle Box
The accumulation of moisture is another major cause of GFCI tripping. Outdoor installations are the most vulnerable and rain is the most common culprit. However, due to the tropical climate of Florida, high humidity can also cause moisture buildup and make it harder for any water trapped in a receptacle box to evaporate.

Start your search by inspecting the receptacle box. Be sure to turn off the breaker before opening the box containing the receptacle. The box must be dry before you attempt to reset the GFCI. It is possible to speed up this drying process using a simple tool such as blow dryer, but that part is best left to a professional.

If the installation is outdoors or located in high humidity areas, such as the bathroom or kitchen, make sure the box is weatherproof and locked even when the receptor is in use. The presence of moisture can expose you to the risk of accidental electric shock.

3. Overloaded Circuit
Circuit overload occurs when more amperage flows through an electric wire or circuit than it can handle. This may happen if you connect malfunctioning or defective appliances. Loose, corroded wires or connections may also be to blame. Once the GFCI outlet senses an overload, it trips or “breaks” the circuit.

If you want to determine if overloading is really the problem, follow these steps in order.

Unplug all the appliances connected to the circuit in question
Reset the circuit on your fuse box
Wait several minutes
Plug an appliance back in and turn it on
Check to see that your circuit has not tripped
Plug in the next appliance, turn it on, check the breaker and so on
You may find you’ll need to replace the items causing the problem.

If the problem keeps reoccurring, you may need a new dedicated circuit and outlet that can handle the amperage required by the appliances.

4. Electrical Fault
If your GFCI outlet trips consistently, it could be an electric fault resulting from faulty structural wiring. An electrical outlet connected to the same circuit could also be the source of the problem, especially if it was not part of the original wiring of your home. In the case of an electrical fault, you will need a professional electrician to fix the problem.

5. Faulty GFCI Outlet
If you’ve tried all else and the GFCI outlet reset doesn’t solve the problem, that means outlet itself is defective. GFCI have highly responsive internal circuitry to detect whenever there’s a flaw in the electric system. With time, the sensitive circuitry wears out, rendering the outlet dysfunctional. In this case, the outlet will need repairing or even replacing and should be done by a qualified electrician.