What is a GFCI?

And How Does it Work?

What is a GFCI?

GFCI stands for ground fault circuit interrupter. It is an electrical device designed to protect people from electric shock. The most common type is GFCI outlets. You can identify them by the reset button, and they are usually located in the bathroom and kitchen. However, you will not find them in older homes.

What is a Ground Fault?

A ground fault is when electrical current flows through an unintended path to the ground. The typical path of electricity starts from power lines outside. Next, it goes to your breaker box(service panel). Then, it goes through a breaker and out the hot wire of a circuit. After it goes through an electrical fixture, it returns to the electrical panel through the neutral wire.

Ground faults are more common around a water source, such as a plumbing fixture, and the unintended path to the ground could be a human body. Needless to say, this can cause serious injury.

It’s important to note that a ground-fault circuit interrupter will detect short circuits, and that’s why we still use standard circuit breakers.

example of how gfcis work

image from https://www.electricaltechnology.org/2020/06/difference-between-gfci-afci.html

How Does a GFCI Work?

GFCI receptacles work by detecting tiny current imbalances between the ungrounded and grounded (aka the hot wires and neutral wires ) conductors. GFCIs can detect an imbalance of as little as 5mA and shut off in less than one-tenth of a second. In addition, they stop the flow of electricity to all electrical devices downstream.

The imbalance a GFCI detects happens when the electrical flow takes an unintended path. This alternative path could be through you (electrical shock)! This happens when you are simultaneously in contact with the ground or a grounded conductor and an energized part of the circuit. GFCI devices are required in areas prone to water contact, such as bathrooms, kitchens, garages, crawlspaces, and the exterior of your home. Although they may not have been required when your home was built, upgrading these areas to have GFCI protection is a good idea.

Where is a GFCI Required?

The National Electrical Code (NEC) regulates GFCI requirements. As of the 2020 NEC, GFCIs are required for receptacles in bathrooms, garages, outdoors, crawl spaces, basements, kitchen countertops, six feet from any sink, laundry rooms, and any damp indoor location.

It’s important to note that every electrical outlet in these areas needs to be a GFCI outlet. A GFCI device stops electrical current through the rest of the circuit. For example, a gfci circuit breaker protects all the standard outlets in the circuit.

GFCI requirements have changed over the years. So use the GFCI requirement chart below to see what was required when your home was built.

gfci requirement reference chart

Can a GFCI go bad?

GFCIs do fail in about 10-20 years. They may fail to trip when you press the test button. Also, they may fail to reset after tripping.

How to replace a GFCI?

Replacing a failed GFCI is simple. First, turn off the power to the circuit. Make sure you use a non-contact voltage detector to ensure the power is off. Second, use a screwdriver to remove the screw in the cover plate. Continue removing the screws in the receptacle and pull the GFCI out. Pro TIP: Take a photo of the wires to refer to when reinstalling. Next, use a screwdriver to loosen the wire screws, unhook the wires, and remove the receptacle. Now, go backward with your new GFCI receptacle.

However, if you don’t feel comfortable, you should call a professional electrician.

Testing Receptacle-Type GFCIs

Receptacle-type GFCIs are currently designed to allow for safe and easy testing that you can perform without any professional or technical knowledge of electricity. GFCIs should be tested right after installation to ensure they are working correctly and protecting the circuit. You should also test them once a month to ensure they are working correctly and providing protection from fatal shock.

To test the receptacle GFCI, first, plug a nightlight or lamp into the outlet. The light should be on. Then press the “TEST” button on the GFCI. The “RESET” button should pop out, and the light should turn off.

If the “RESET” button pops out, but the light does not turn off, it is improperly wired. Contact an electrician to correct the wiring errors.

If the “RESET” button does not pop out, it is defective and should be replaced.

If the GFCI is functioning properly and the lamp turns off, press the “RESET” button to restore power to the outlet.