Ground Fault Circuit Interrupters: How They Work and How to Install Them

Ever since introducing a ground fault circuit interrupter (GFCI outlet) in 1973, deaths from electrical shock have reduced by 83%.

The GFCI outlet or residual current drive (RCD) is a fast-acting circuit breaker that shuts off power once it senses a ground fault. The receptacle works by comparing the input and output current from electrical appliances.

When the input current differs from the output (current leakage) by, say, 0.005 amps, the breaker trips.

Ground fault and what it means.

Under normal conditions, currents flow through insulated wires to various outlets and appliances. But when a ground fault occurs, currents find their way to the ground.

A ground fault occurs when electricity follows an unintended path to the ground. Common causes include faulty wiring and damaged cords.

When a ground fault occurs, the current flows through any conductor around. If the conductor is a human being, electrocution occurs. But since water is an excellent conductor of electricity, a greater chance of ground faults occurring in areas such as the bathroom and kitchen is always higher.

How GFCI outlets work

The outlet works like circuit breakers and fuses. But while breakers protect wires and receptacles from overheating, GFCI protects humans from electrocution.

The surge arrester has a sensor that detects when the input and output current varies. When the current differs, even with 4 or 5 milliampers, it trips.

That is why we install it in the bathroom and kitchen, where skin contact with the ground and metallic objects are common.

GFI also protects against fires from short circuits and other electrical faults that do not involve humans. For example, a low current that has not reached the tripping point for a circuit breaker.

That is why the National Electrical Code recommends the installation of ground circuit interrupter on every building.

Types of residual current drive (RCD)

There are three types of GFCI, they include:

  • GFCI outlets
  • GFCI circuit breaker
  • Portable GFCI.

GFCL outlet

This is the most commonly used among the 3 receptacles, similar to a wall outlet, it protects any appliance plugged into it. It can also be wired to protect other outlets connected to it.

GFCI circuit breaker

Ground fault circuit breakers protect the entire circuit. When you install one on your service panel, it protects the entire circuit, appliances, wiring, and other devices connected to it.

Instead of installing several receptacles in your home, install one GFCI circuit breaker for complete protection.

Temporal or Portable GFCI

This is the type of ground fault interrupter we use on mobile applications, gardens, and in construction sites. You can also use it outdoors, on electrically powered appliances.

However, do not use it as a permanent option for a normal GFCI device.

How to install the arc fault circuit interrupter

Installing or replacing a worn out GFCI is quite easy, just follow these steps.

  • Turn OFF power from the circuit breaker
  • Loose out the existing outlet with your screwdriver
  • Inspect the wires and mark how they are connected
  • Replace the reciptacle and place it back on the wall.

How to test your ground fault breaker.

Testing your GFCI outlets is easy, you can do it yourself. Experts recommend testing it once every month and replacing the outlet every decade.

To test it, look at the face of the outlet. Between the slots where you plug in cords, lie two rectangular buttons labeled ‘TEST’ and ‘RESET’.

Press the test button to shut off the power. Confirm if the outlet is OFF, using your multimeter or by plugging in a device in the slot. Once you confirm it, press the reset button to restore the current to it.

Benefits of installing ground fault circuit breaker

Since introducing residual current drive (RCD) by NEC, electrical shocks have reduced. Below are their benefits;

  • It prevents electrical shock.
  • Prevent electrical fires.
  • Protect electrical appliances from damage.

Difference between AFCI outlet and GFCI

Arc-fault circuit interrupters (AFCI) and ground-fault circuit interrupters (GFCI) are both electrical devices that protect against fire and electric shock.

The law requires that we install them in every new building. While they do almost the same work, their difference lies in the area they protect.

AFCI detects electrical faults within your circuit, which may damage your wiring system and appliances. (They protect wiring systems and appliances).

Meanwhile, the GFCI protects human beings from electrical shock.