GFCI and AFCI are both safety measures, but they are distinct and not interchangeable. Let’s compare and contract GFCI vs AFCI so you can be sure you’re getting the right thing.
If you don’t know, buying combination GFCI/AFCI outlets or breakers is an option, and it’s not a bad idea. But if you can’t afford the higher price for a combo unit, or want to maximize convenience, knowing GFCI vs AFCI is important so you get the right safety feature for your application.
Learning GFCI vs AFCI the hard way
I learned about GFCI vs AFCI the hard way. I bought a house, and it was full of ungrounded outlets. The seller paid someone to fix the problems my home inspector found. The contractor chose to install GFCI circuit breakers at the panel rather than replace all of the outlets, since ungrounded GFCI outlets are acceptable, at least per my local code. But then the house failed the occupancy inspection. What I found was that the contractor who did the work installed a mixture of AFCI and GFCI breakers. So when the inspector tried to trip the GFCI, those outlets didn’t trip.
It was probably an honest mistake. Somehow I found out what the seller paid to get the work done, and it was much lower than anyone I know would have charged for that work. I think the guy who did the work did a rush job to make up for bidding the work too low. The breakers probably got mixed up at the store, and the guy who installed them either didn’t notice, or installed them anyway, hoping no one else would notice.
What GFCI does
Between GFCI and AFCI, you’re probably more familiar with GFCI. Every kitchen and bathroom is supposed to have them. If something interjects itself into the normal flow of electricity and provides a closer path to ground, the GFCI trips. An example of this would be dropping a hair dryer into the sink or bathtub. When I was growing up, they used to tell you that using a hair dryer in the tub was a good way to electrocute yourself. You still shouldn’t use a hair dryer in the tub, but a properly working GFCI should cut off the flow of electricity before it can kill you.
This is on top of the protection that a ground plug provides. As far as protecting human life is concerned, having GFCI is an appropriate substitute for not having a ground. When it comes to protecting the device you plug into the outlet, it might not be. But building codes are mostly concerned with preserving human life, so that’s why they allow us to make that substitute.
GFCI protects against wet conditions, but you’re also supposed to use them in basements and garages. An uncovered cement floor isn’t a great conductor of electricity, but it’s much better than carpet, vinyl, or wood, especially if it’s wet.
Most commonly, we install GFCI outlets where we need GFCI, but you can also buy GFCI circuit breakers, which effectively turn any outlet attached to them into GFCI. It’s convenient to install, but less convenient when it trips since you can’t just push a button on the outlet. You have to find the tripped breaker and reset it there.
What AFCI does
GFCI stands for Ground Fault Circuit Interruptor. AFCI stands for Arc Fault Circuit Interruptor. Hey, three of the words are the same. It’s also a safety feature, but it’s protecting you against a different kind of fault.
AFCI protects you against wiring problems. An arc is when electricity flows, but the wiring puts up a fight. This causes heat, and if it continues for a long time, it can cause a fire. The circuitry in an AFCI detects this and trips, interrupting the flow of electricity if the wires get too hot. This protects you against worn out wiring in the house, and also worn-out power cords or extension cords, keeping a small problem from turning into a house fire.
It’s not at all interchangeable with GFCI, because it protects against a completely different problem. It’s still a good idea, and the National Electric Code has been requiring AFCI in new construction for years now.
Like GFCI, you can buy AFCI outlets or breakers. But with AFCI, the difference isn’t a matter of convenience. AFCI breakers are definitely more effective. If the arc occurs in the wiring running to a light fixture, an AFCI outlet can’t do anything about that unless it happens to be in the way. But the AFCI breaker will be in the way, so it will trip under those conditions.
There’s one more distinction when it comes to GFCI vs AFCI. You generally aren’t supposed to run heavy appliances on GFCI, at least if you ask my local inspectors. While local rules can vary on AFCI when it comes to heavy appliances, there’s no harm in running them on AFCI.
Combination GFCI and AFCI
At the time my GFCI vs AFCI mixup occurred, you couldn’t get combination GFCI/AFCI devices, at least not locally. Today you can. That makes GFCI vs AFCI a little easier to deal with. If you don’t know, you can just pay a little extra and get both. Frankly it’s not a bad idea. We can’t anticipate everything that can go wrong, so having both safety measures in place definitely helps.
Now, when cost isn’t a consideration and you want to maximize convenience, do this instead of buying combination GFCI/AFCI devices. Install AFCI at the breaker. Then install GFCI outlets in the rooms that need them. That way, when you get a GFCI trip, you don’t have to go to the breaker box to reset it. And then you aren’t GFCI-protecting heavy appliances like refrigerators, which, if you go by the book, you aren’t supposed to do.
David Farquhar is a computer security professional, entrepreneur, and author. He started his career as a part-time computer technician in 1994, worked his way up to system administrator by 1997, and has specialized in vulnerability management since 2013. He invests in real estate on the side and his hobbies include O gauge trains, baseball cards, and retro computers and video games. A University of Missouri graduate, he holds CISSP and Security+ certifications. He lives in St. Louis with his family.