Installing a GFCI outlet in every American household can prevent over 300 electrocutions each year. In this post, we explain what a GFCI outlet is, compare the terms GFCI and GFI, compare breakers to outlets, outline the rules and name the cables used in GFCI outlets.

What is a GFCI outlet?

GFCI stands for Ground Fault Circuit Interrupter outlets. This outlet protects people from electric shocks (ground faults) by quickly cutting off power when they detect an imbalance between the incoming and outgoing current. A ground fault occurs when an unintended connection forms between a power source and a grounded surface, creating an abnormal electrical pathway. 

The outlet works by monitoring the electricity flowing in the circuit with the help of special sensors. Regular electric outlets do not offer such protection.

The GFCI outlet can be visually recognized based on a red reset button on its faceplate.

GFCI vs. GFI

GFCI and GFI outlets are the same thing. GFCI stands for ground fault circuit interrupter, and GFI stands for ground fault interrupter, which are identical. You will encounter these terms interchangeably, but GFCI is a more common term.

GFCI/GFI is different from AFCI arc-fault circuit interrupter, which protects not from the ground faults, but from arching faults resulting from faulty wiring.

GFCI breaker vs. GFCI outlet

If you are choosing the type of GFCI protection, the question that you will arrive at sooner or later is whether to select a GFCI circuit breaker or a GFCI outlet (receptacle). The function of GFCI breakers and GFCI outlets is the same - they both detect the imbalance in the electrical circuit and cut off the power if the imbalance is detected.

Both GFCI breakers and GFCI outlets will be useful in your house for ground fault protection. A GFCI circuit breaker is a superior choice for protecting the entire house from ground faults, while a GFCI outlet is the best for individual outlets. 

Individual GFCI outlets are a cost-friendly option for localized protection. They are a great solution when only some outlets at the breaker require protection and others don't. Another great reason to use them is when the breakers are located too far away from the panel box. They can be reset directly at the outlet, while circuit breakers are reset at the service panel. 

Outlets should not be installed behind furniture and appliances. In this case, a circuit breaker is a better option.

Naturally, a GFCI outlet and a GFCI circuit breaker should not be installed on the same circuit.

Requirements for GFCI Outlets

• The rules for GFCI outlets in the United States are outlined in the National Electric Code.
• GFCI outlets are required to be used in wet or damp areas, anywhere where the water is present. These include residential buildings, commercial buildings, and public objects.
• In сommercial and non-commercial buildings, GFCI outlets are required in bathrooms, toilets, garages, outdoor areas, kitchens, laundry areas, usable rooftops, basements, locker rooms, areas with sinks, and other damp areas. 
• Every exterior outlet should be GFCI.
• GFCI outlets are subjected to monthly testing. They are also tested right after the installation and after every power outage, even unrelated ones. The outlets are tested by plugging in a lamp and using the test button, followed by the rest button.
• GFCI outlets expire in 15-25 years, so it is recommended to replace them every 10-15 years.
• GFCI outlets can also be used when working with DIY electric tools around the house and gardening tools.
• Large appliances like refrigerators and freezers should not be installed in a GFCI outlet as they might overload the circuit.
• Emergency lighting should not be protected by GFCI.

Types and Sizes of Cables for GFCI Outlets and Circuit Breakers

• It is not required to use any special cables with GFCI outlets and circuit breakers. The cables that are used with any outlet or circuit are a solid choice. 
• The cables used for GFCI protection are supposed to have a hot wire, a neutral wire, and a hot wire.
• As for the size, use 14 AWG for 15-amp circuits and 12 AWG for 20-amp circuits.
• The most common cable for GFCI is NM-B Romex.
• Other acceptable cable types are Type MC cable, UF-B cable for underground service and as a direct burial cable, and THHN/THWN-2 and XHHW-XHHW-2 in conduit (for commercial/industrial installations.