Find Out What a GFCI Outlet Is and How It Works

Paige Bennett
Written by Paige Bennett
Updated April 19, 2022
Ground fault interrupter electricity receptacle and wall plate.
Photo: The Toidi / Adobe Stock

The special outlets in your bathrooms, kitchen, and outdoor spaces are designed to keep you safe

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Have you ever wondered why some of your outlets have reset buttons while others don’t? It’s all in the name of safety, and those special outlets with extra buttons are called GFCI outlets. Find out what a GFCI outlet is, how it works, and why it’s crucial to keeping you and your family safe.

How Does a GFCI Outlet Work?

Most of us rarely think about outlets until we’re searching for a place to charge our phones or other essential devices around our homes. And let’s face it: most of us charge our devices in virtually any outlet we can. But not every outlet offers the same charge or protection from electrocution. 

A ground fault circuit interrupter (GFCI) outlet is designed to prevent electrocution. The National Electrical Code requires these outlets. 

So, how can a GFCI outlet stop serious electrocutions? The outlet will cut power, or trip, to stop the electrical current if it detects any minor changes, even as small as four to five milliamps. This prevents a ground fault when electricity flows outside the intended circuit and is working to reach the ground through any path necessary, even the human body. 

If the GFCI outlet notices excess energy or an abnormal flow, it can cut the power in less than 1/30 of a second before the electricity reaches the heart. You might still feel a shock, but this outlet helps prevent serious injuries and deaths.

GFCI vs. Standard Outlet

A GFCI outlet is easy to detect because it has a “Reset” and a “Test” button on the outlet’s face between the two plug-ins.

A standard outlet cannot protect you from accidental shocks. Similarly, a circuit breaker won’t protect you from electric shocks but will protect your home’s electrical system by cutting power when it notices abnormalities, like excess energy or a short circuit.

Types of GFCIs

There are three main types of GFCI outlets.

  • Receptacle: This is the most common GFCI outlet type and resembles traditional outlets. It is either wired as a single-location outlet, which protects just one outlet, or as a multiple-location GFCI, which will protect all outlets, even standard, downstream outlets.

  • Circuit Breaker: A circuit breaker GFCI will protect an entire circuit, protecting both the electrical system (like a standard circuit breaker) and humans (like a GFCI outlet). This is ideal for outdoor spaces and garages with several GFCI outlets.

  • Temporary: Never use a temporary GFCI for permanent use. Instead, pros often use this type for construction as well as power tools or mowers.

Where Should You Install GFCI Outlets?

Person resetting GFCI outlet
The Toidi -

The National Electrical Code requires GFCI outlets in several locations throughout your home. There should be GFCI for outlets within six feet of a sink or water source. If the outlet is likely to come into contact with water, there should be a GFCI outlet.

  • Bathrooms: Bathrooms were the first place for GFCI outlets to be required. All 15- and 20-amp, 125-volt outlets in bathrooms require GFCI protection.

  • Kitchens: GFCI outlets must be within six feet of a sink, wet bar, or another water source.

  • Garage: All 15- and 20-amp, 125-volt outlets in the garage must be GFCI outlets. You might also consider a GFCI circuit breaker if you have several outlets in your garage.

  • Basements: If you have an unfinished basement, it must have GFCI outlets. If you have a finished basement with a bathroom, bar, or another water source, it also requires GFCI outlets. If your finished basement is simply a home theater or art studio with no sinks, standard outlets

  • Laundry Rooms: A recent 2005 revision of the National Electrical Code requires all 15 and 20-amp, 125-volt outlets in laundry rooms to have GFCIs.

  • Outdoor Spaces: Planning to install some fairy lights over your patio? Make sure you are GFCI protected. The National Electrical Code requires all outdoor outlets to have GFCI protection and weatherproof covers. Outdoor outlets must be no higher than 6.5 feet above a walking surface because they must always be within easy reach.

  • Crawl Spaces: Crawl spaces require GFCI outlet protection, but because they can be harder to access, pros recommend GFCI circuit breakers for this area.

Bedrooms, living rooms, or offices do not require GFCI outlets. But if you want the added safety, consider replacing ungrounded outlets with GFCI outlets for more protection.

How to Test GFCI Outlets

As you can see, GFCI outlets are essential for preventing electrocution. Just make sure to test them regularly, about once a month, to ensure they are working properly.

  • Plug in a lamp, alarm clock, or other small devices into the GFCI outlet.

  • Turn on the device.

  • Press the test button.

  • You should hear a click, the device should shut off, and the outlet’s reset button should pop out.

  • Press the reset button to restart the GFCI protection.

If the lamp or other small device does not shut off, you need to call an electrician immediately to replace the old GFCI outlet. A malfunctioning GFCI outlet could lead to serious and even fatal injuries.

How to Install GFCI Outlets

If you want added protection in various rooms throughout your home, you might consider installing GFCI outlets in your bedrooms and living room.

But working with electricity is dangerous and can be fatal. It’s best to hire an electrician to help you install GFCI outlets and circuit breakers. The cost to install or replace GFCI outlets is about $150 per receptacle, and this price includes materials and labor.

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