By now, everyone is familiar with the bathroom GFCI outlet, but its history isn't that long, and the National Electrical Code (NEC) was slow to adopt it. Invented in 1961 by University of California engineering professor Charles Dalziel, the ground fault circuit interrupter (GFCI) made its first appearance in the NEC in 1971— just after the moon landing — and according to the Real Estate Inspection Company, it wasn't required in bathrooms until 1975. Today, there are few rooms in the house in which GFCIs aren't required, but because code changes don't apply to wiring that predates the changes, many older homes still don't have them.
If yours is a house that doesn't have GFCI protection, either in the form of outlets or circuit breakers, you're missing out on an important technology that saves lives and prevents fires. The bathroom GFCI is perhaps the most important one in the house because everyone uses the bathroom, and it's one of the places where ground faults are most likely to occur. It's actually fairly easy to provide GFCI protection for the bathroom, and while the most effective strategy involves installing circuit breakers, you can do it without working in the electrical panel.
What Is a Ground Fault?
Long before GFCIs came on the scene, the NEC required all household circuitry to be grounded, which prevented shocks while flipping light switches and plugging in appliances. The path provided by the ground wire prevents residual electricity from collecting where it isn't supposed to, such as on switch toggles and frayed appliance cords, by directing it to the earth, which is the largest receptacle for stray electricity available.
If damaged conductor insulation or a faulty terminal allows a hot wire to come in contact with the ground wire or a grounded metal electrical box, the result is an electrical current surge that can cause electrocution or start a fire. That's called a ground fault.
A ground fault can also occur if a person touches an exposed wire and creates a path to ground, and it can cause a severe electrical shock or even electrocution. You may have heard stories of people being electrocuted while standing in bare feet on a wet floor or in the bathtub while holding a hair dryer with insufficient electrical insulation. They caused a ground fault by providing a path for electricity to flow, and that's the type of accident a GFCI receptacle is designed to prevent.
How Does a Bathroom GFCI Outlet Protect You?
A GFCI outlet or circuit breaker contains a sensor that detects the current surge of a ground fault, and it has a breaker that switches off the power, usually in as little as 0.25 seconds. That's still enough time for a shock to occur, but because the shock isn't a prolonged one, it's less likely to cause injury or start a fire.
The bathroom GFCI outlet is recognizable by the two pushbuttons on its face. The top one, which is often black, is a test button, and when you press it, the breaker should trip, which is how you know your bathroom GFCI outlet is working. The bottom one, which is usually red, is the reset button, and you have to press it to restore power after the outlet has tripped. The reset button pops out after tripping, and you push it back in until it clicks.
Three Ways to Get GFCI Protection
The first and most expensive way to get ground fault protection in the bathroom is to replace all the electrical outlets with GFCI receptacles. This is usually unnecessary, however, because there are two easier options that are just as effective.
One is to install a GFCI circuit breaker in the electrical panel to control the outlet circuit, which must be dedicated to the bathroom to satisfy code. Once the breaker is in place, you can install standard 20-amp outlets in the bathroom, and they will all be GFCI protected by the breaker. Unlike a standard breaker, a GFCI breaker has a neutral wire that connects to the neutral bus in the panel, so if you aren't comfortable doing this yourself, call a licensed electrician.
The other option is even easier, but it may require some circuit detective work on your part. The bathroom outlets are daisy-chained together, and if you can locate the first one in the chain, which may or may not be closest to the electrical panel, all you have to do is replace that outlet with a GFCI, and that outlet will protect all the ones that come after it in the circuit. A DIYer can identify the outlet by turning off the circuit breaker, disconnecting the prime suspect outlet, turning the breaker back on and verifying that all the other outlets lose power. If not, try another outlet.
How to Install a Bathroom GFCI Outlet
A GFCI outlet differs from a standard one in an important way. Both have two hot terminals, two neutral terminals and a ground terminal. On a standard outlet, the two hots are interchangeable with each other, as are the two neutrals, but on a GFCI outlet, they aren't.
One pair of terminals, called the LINE terminals, are for the incoming circuit wire, and the other pair, the LOAD terminals, are for daisy-chaining outlets farther down the circuit. If you mix these up, the outlet will still work, but it won't provide ground fault protection.
Step 1: Turn Off the Power
Locate the breaker for the circuit and turn it off. It's good practice to test the wires with a voltage tester to make sure they're dead before you touch anything. Even after checking, you should wear rubber gloves and use insulated tools for safety.
Step 2: Disconnect the Old Outlet
If you're replacing a standard outlet, disconnect the incoming and outgoing hot and neutral wires and label them with tape. If you don't know which pair is which, separate the wires, turn on the breaker, test each pair with a voltage tester to see which gives you a positive reading and turn the breaker back off.
Step 3: Identify the LINE and LOAD Terminals
Most GFCI receptacles come with a piece of tape applied across the LOAD pair of terminals, but if this tape is missing, you'll see LINE and LOAD clearly marked on the back of the receptacle housing. If the tape is there and you don't plan on wiring a load, you can leave it in place.
Step 4: Hook Up the Hot and Neutral Wires
GFCI outlets don't have push-and-lock inlet holes, so you have to wrap each wire clockwise around the corresponding terminal screw and tighten the screw with a screwdriver. Hot wires always attach to brass screws and neutral wires to chrome ones.
Step 5: Connect the Ground Wires
Join the ground wires that you are going to connect to the outlet either by twisting them together with pliers or crimping them with ground crimps. Leave one wire longer than the other, wrap it clockwise around the green ground screw and tighten down the screw.
Installing a GFCI in Ungrounded Circuitry
If your house is too old to have grounded circuitry, you can still install a bathroom GFCI outlet and it will protect you, but it won't ground any device you plug into it. For this reason, the code requires you to affix a label that says "no equipment ground" to the outlet cover. This label usually comes with the outlet.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker.com.