What is a GFCI?

I’m starting off my Minnesota home inspection blog to address the quizzical look I often receive when I start rambling on about the lack of GFCI protection. My intent is to keep this simple, concise, and understandable. So without going into too much detail, I will explain GFCI protection.

GFCI stands for Ground-Fault Circuit Interrupter. A GFCI is a protection device meant to interrupt an electrical circuit in the event of a ground-fault.

So what exactly is a ground-fault? Electricity in a properly functioning circuit will travel from the hot conductor (usually black or red) to the neutral conductor (usually white), these are the two prongs in a two-pronged receptacle. Should, for any reason the path of electricity stray from this intentional path, it will seek a path of the least resistance to the earth to complete the circuit.

This may occur when a wire touches a metal electrical box, a water pipe, or any electrically conductive materials with the potential to become energized. To help protect against this, a 3rd wire is added to electrical systems and components, a ground wire. This is the 3rd prong on modern electrical receptacles, and under normal circumstances it does nothing. Should electricity stray from its intentional path, the 3rd ground wire (often green or bare copper) provides an alternative path for electricity to ground. Under normal circumstances, a circuit breaker will trip if this occurs, disabling the circuit. However, even before tripping this could be fatal if you happen to interrupt this path.

An added level of protection is offered by a properly functioning GFCI protected circuit. A GFCI measures the differential in current between the hot and neutral and should this exceed approximately 5 milliamperes it will shut off electric power in as little as 1/40 of a second, ideally preventing a fatal shock.

Although not required by code I recommend replacing 2 prong receptacles with a GFCI if adding a functional ground is not feasible. This is because the GFCI will still work by comparing the amount of current going to and returning from equipment along the hot and neutral wires. When the amount going differs from the amount returning by approximately 5 milliamperes, the GFCI interrupts the current. This is a great safety upgrade.

It may not necessarily be required by code but I recommend GFCI’s in any area that may be susceptible to water contact. This includes outdoors, garages, unfinished basements, laundry rooms, utility rooms, bathrooms, kitchens, and within 6 feet of areas of water. I’m not a code inspector, rather a Minnesota Home Inspector and while I do educate myself on current code requirements, I care more about the best and safest building practices. This means I’m not looking at when or where a home was built, but rather what are the current best practices in the industry.

What is a GFCI?