GFCI and AFCI protection: what they do and where homes need them
Updated · KeystoneProGuide editorial team
What is the difference between a GFCI and an AFCI?
They guard against different dangers. The National Fire Protection Association explains that a ground-fault circuit interrupter is designed to protect people from shock from ground faults, such as those from a defective appliance or corded tool, while an arc-fault circuit interrupter shuts off electricity when it senses abnormal arcing, the kind of fault that can start a fire.
The Electrical Safety Foundation, a nonprofit safety group, describes the mechanics. A GFCI cuts the power if the current flowing into a circuit differs by even a slight amount from the current returning. It says a person who becomes part of the path for that leaking current will be severely shocked or electrocuted. An AFCI replaces a standard breaker in the panel (it also comes as an outlet) and detects arc faults caused by damaged, overheated or stressed wiring or devices, which the foundation says may otherwise be hidden from view until it is too late.
What causes the arcing an AFCI detects?
Everyday things. The NFPA gives two examples: a nail driven into a wall to hang a picture that touches a wire, and an appliance plugged in with a defective cord. It says such arcing is rarely seen.
Where are GFCIs needed?
Wherever water and electricity can meet. The NFPA says GFCIs should be installed by a licensed electrician in bathrooms, kitchens, garages and basements, and that all outdoor receptacles should have GFCI protection. The foundation says a GFCI should be used in any indoor or outdoor area where water may contact electrical products.
Where are AFCIs needed?
In most living spaces. The foundation says the National Electrical Code has required AFCIs to protect almost every circuit in the home since its 2008 edition, and that a U.S. Department of Housing and Urban Development report listed the absence of AFCIs among the primary residential hazards for burns and fire injuries.
For renovations, the foundation summarizes the 2020 code room by room:
| Area being renovated | Protection ESFI lists under the 2020 code |
|---|---|
| Bathrooms | GFCI |
| Kitchens | AFCI, and GFCI for countertop receptacles or within 6 feet of a sink |
| Laundry areas | AFCI and GFCI |
| Bedrooms, family and dining rooms, dens | AFCI |
| Hallways and closets | AFCI |
| Finished basements | AFCI |
| Crawl spaces at or below grade | GFCI |
| Garages and outdoors | GFCI |
Which edition of the code your municipality enforces under Pennsylvania's Uniform Construction Code was not stated on any page read for this guide, so ask your code office or electrician what applies to your job.
Does an older house have to be brought up to date?
The pages read do not say that existing wiring must be upgraded just because the code has changed. What the safety bodies say is that it is worth doing. The NFPA says that if AFCIs are not installed in your home, you should ask a licensed electrician to install AFCI protection. The foundation suggests asking an electrician whether your home would benefit from it, especially during an inspection of an older home or an upgrade, and lists AFCIs, GFCIs, surge protection and tamper-resistant receptacles as the devices to have installed when you renovate.
Pennsylvania's code regulation exempts ordinary repairs from permits but not added or relocated wiring, so whether a given change needs a permit depends on what the electrician has to do; ask.
What do the devices cost?
Angi, a home-services marketplace, says breakers generally cost $5 to $40 each, with high-amperage AFCI or GFCI breakers reaching $70 or more, and that replacing a breaker with installation costs $100 to $200. These are national figures.
How do you test them?
With the test button, once a month. The NFPA says to test AFCIs and GFCIs after installation and monthly afterwards, following the manufacturer's recommendations. The foundation says the same for GFCIs and adds AFCIs to its monthly list along with smoke alarms.
The NFPA adds three cautions: replace a defective device immediately, because one that no longer works gives a false sense of security; choose devices carrying the label of an independent testing laboratory; and have them installed by a qualified electrician, whether they are the breaker type or the outlet type.
What are tamper-resistant outlets?
Outlets with built-in shutters. The NFPA says tamper-resistant receptacles work like standard ones but have a mechanism that helps stop objects pushed into them from being energized. It says they are required in all new homes, with or without children, because occupants change and children visit. The foundation dates the requirement for new construction to the 2008 code, and the U.S. Fire Administration recommends installing them if you have young children.
The signs that a circuit may already have a problem are in the warning signs guide, what you can safely test and what to leave alone is in doing it yourself or hiring, and prices for common jobs are in the cost guide. Electricians are listed on the electricians directory page.
Sources
- Electrical Home Fire Safety, National Fire Protection Association (NFPA)
- Understanding Your Home Electrical System, Electrical Safety Foundation International (ESFI)
- Home Safety Devices - Renovate Your Home to Code, Electrical Safety Foundation International (ESFI)
- Home Electrical Fires, Electrical Safety Foundation International (ESFI)
- Appliance and Electrical Fire Safety, U.S. Fire Administration
- How Much Does It Cost to Upgrade an Electrical Panel? [2026 Data], Angi
- 34 Pa. Code § 403.62. Permit requirements and exemptions., Commonwealth of Pennsylvania (Pennsylvania Code)