What Are GFCI?

An example of a GFCI outlet.

It’s easy to get confused by some of the terms electricians use when discussing electrical repairs or upgrades. Arc fault this and amperage that — it’s enough to leave your head spinning and send you running to Google for clarification.

To help, we’re going to take a moment to explain one of the terms that often causes confusion: GFCI.  

What Are GFCIs?

Another example of a GFCI outlet -- note the indicator light beside the reset button.

GFCI is an acronym that stands for ground fault circuit interrupter. GFCIs are safety devices designed to help prevent electric shocks by interrupting circuits when they detect ground faults.

Clear as mud, right? Let’s back up for a second.

The amount of current flowing out of an electrical outlet and into a device should be the same as the amount of current flowing back into the outlet from the device. In other words, if 8 amps travel from your outlet to your coffee maker, 8 amps should travel back into the outlet.

GFCIs monitor this. They measure the amount of current flowing out and back into outlets — and they do so with staggering precision. If they detect a difference of only 4 to 6 milliamps (that’s 0.004 to 0.006 amps), they shut down or interrupt the circuit.

Why Do GFCIs Shut Down Circuits?

GFCIs help prevent electric shocks and provide additional safety.

In some cases, electrical circuits or devices can malfunction and allow electricity to leak out. When this happens, the electricity will find its way to the ground — a phenomenon known as a ground fault.

If you have the misfortune of touching anything along this path, you could suffer an electrical shock. But if the device in question is plugged into a GFCI, the circuit will be interrupted as soon as the ground fault is detected, thereby preventing you from being shocked.

This all happens remarkably quickly. A GFCI can shut down a circuit in as little as 25 milliseconds (that’s 1/40th of a second).   

How Can You Tell if an Outlet Is a GFCI?

Spotting a GFCI is easy: Just look for the test and reset buttons.

It’s actually quite easy to tell if an outlet is a GFCI; you can simply look for two small buttons on the outlet. Generally situated between the two receptacle openings, these buttons are labelled “reset” and “test.”

The reset button is used to turn the circuit back on once it’s been interrupted. Say, for example, you plug your malfunctioning coffee maker into the outlet. This causes a ground fault to occur, which causes the GFCI to shut down the circuit.

Once you unplug the faulty coffee maker, you can then press the reset button to restore power to the outlet (if you do so without unplugging the coffee maker, the GFCI would simply keep interrupting the power each time you pressed the button).

The test button does exactly what it sounds like: It tests the circuit to ensure it is working properly by simulating a ground fault. When you press the test button, the circuit should become interrupted and require you to hit the reset button. If this doesn’t happen, the outlet is malfunctioning and in need of replacement.  

Where Are GFCI Used?

GFCI outlets come in an array of colors.

The National Electrical Code (NEC) requires any outlet to be a GFCI in a few key situations. This generally includes anywhere where there’s a higher risk of electric shock due to moisture or grounding conditions.

This means you’re likely to see GFCIs in the following places:

·         Bathrooms

·         Kitchens 

·         Laundry areas

·         Basements 

·         Garages

·         Utility rooms

·         Outdoor outlets 

·         Dishwashers

·         Garbage disposals

·         Hot tubs

·         HVAC Equipment  

Get GFCIs Installed at Your House

Ryan, after installing a GFCI for a customer.

GFCI installation is a pretty simple project that can keep your home or business safer and help prevent electric shocks. It’s not terribly expensive, nor does it take much time. Schedule a knight today to get started!

We’ll be happy to examine your home’s existing electrical system, identify the places you should have GFCIs installed, and get to work providing these key safety upgrades. And as always, we’ll be happy to explain any of the unfamiliar electrical terms we use in plain English, so that you are crystal clear about everything we’ll be doing.