When electricity manages to escape from the boundaries of the wiring in an appliance, a power tool, or a light fixture, it will attempt to take a new route to the ground – a process called a ground fault. An electrocution occurs when a human being unknowingly offers his or her body as a medium for that new route. Electricity passing through a human being can be damaging, and sometimes even deadly.
That’s why in 1961, a professor of electrical engineering at the University of California by the name of Charles Dalziel invented the ground fault circuit interrupter, which is now commonly referred to as a GFCI or GFI. Dalziel’s invention is a device that protects you from receiving shocks when electrical appliances malfunction. Let’s take a look at how these devices work, where they’re needed around the house, and how you can test them safely.
How does a GFCI work?
A ground fault circuit interrupter is composed in the same way as most other electrical outlets. You’ll see two vertical slots, a round role centered just below them, and test and reset buttons (more on those buttons later). You’ll notice that of the two vertical slots, the left slot is slightly taller than the one on the right. The left opening is referred to as “neutral”, the right slot is called “hot”, the round hole is called “ground”.
When electrical appliances are in proper working condition, the electricity used will flow from hot to neutral. If there is an imbalance in that current, even a slight difference of four or five milliamps, it means that there is electrical current is leaking out somewhere – and that leak could quite possibly run through someone’s body.
A GFCI monitors the electrical current flowing from hot to neutral, and if any sort of imbalance is detected, it will cut off the flow of electricity to the appliance. The GFCI can react and stop the current in as quickly as one-thirtieth of a second, greatly reducing the chance of a human being suffering any sort of tissue damage from the wayward current.
Where you should have GFCIs around the home
It’s hard to think of a location around the house that wouldn’t benefit from the presence of a GFCI switch, but they’re of particular importance in areas where moisture could come into contact with outlets. The presence of moisture significantly increases the risk of an accidental electrical shock. So the most pertinent places for GFCI switches are kitchens, bathrooms, garages, crawl spaces, basements, laundry rooms, and utility rooms. Local building authorities can have other requirements for installing GFCIs as well.
How to test a GFCI device
Like any electrical device, a GFCI can become damaged or wear out over time, so it’s important to test them routinely and verify they’re in proper working condition. A monthly check is the usual recommendation. Pushing the “test” button on the GFCI device should turn off the power to the circuit. Pushing the “test” button should also cause the “reset” button to pop out. Remember to push the “reset” button to get the power flowing again.
In some instances, a GFCI may be installed on your electrical panel. This may be for a hot tub, or a jet style bathtub. Be sure to test these once a month as well. In some cases, these will not have a reset button. Thus to reset these switches, you have to flip it all the way to the off position, and then back to the on position.