If you’ve ever bought a breaker or had electrical work done, you’ve probably encountered the terms AFCI and GFCI. They sound similar, they’re often confused, and they do completely different jobs. Here’s the breakdown.
GFCI — Ground Fault Circuit Interrupter
What it protects against: Electric shock from ground faults — situations where current is flowing somewhere it shouldn’t, like through a person.
How it works: It monitors the difference between current flowing out and current returning. If there’s a discrepancy (even as small as 5 milliamps), it shuts off in about 1/40th of a second — fast enough to prevent electrocution.
Where it’s required (per NEC):
- Bathrooms
- Kitchens (countertop outlets within 6 feet of a sink)
- Garages
- Outdoor outlets
- Basements
- Areas near pools or hot tubs
You probably already know GFCI from the outlets with the little TEST/RESET buttons. A GFCI breaker does the same job but protects the entire circuit from the panel.
AFCI — Arc Fault Circuit Interrupter
What it protects against: Electrical fires caused by arc faults — unintended electrical arcing from damaged wiring, loose connections, or a nail through a wire inside a wall.
How it works: It detects the specific electrical signature of an arc and trips the breaker before it can ignite surrounding materials.
Where it’s required (per NEC):
- Bedrooms (required since 1999)
- Living rooms, hallways, kitchens, and most other living spaces (expanded in 2014 and 2017 NEC updates)
Local codes vary — not every jurisdiction has adopted the latest NEC — so check with your local building department if you’re doing permitted work.
Can You Have Both?
Yes, and sometimes you need both. Dual-function AFCI/GFCI breakers exist and cover both requirements in a single unit. They’re more expensive but required in some locations — bathrooms and kitchen circuits, for example, may require both protections.
Quick Reference
| GFCI | AFCI | |
|---|---|---|
| Protects against | Shock | Fire |
| Typical locations | Wet areas | Living spaces |
| Detects | Ground faults | Arc faults |
When in doubt about what your specific project requires, pull the permit and let the inspector tell you. That’s what they’re there for.