⚡ GFCI
Protects: People from electrocution
Detects: Current leaking outside the circuit (≥ 5mA)
Trips in: ~25 milliseconds
NEC rule: 210.8 — wet/damp locations
Where required: Bathrooms, kitchens, garages, outdoors, pools, unfinished basements
🔥 AFCI
Protects: Property from arc-fault fires
Detects: Arcing signatures in circuit waveform
Trips in: Milliseconds after arc detection
NEC rule: 210.12 — dwelling living areas
Where required: Bedrooms, living rooms, hallways, kitchens (2020 NEC), laundry areas
What Is a GFCI — How It Works
A Ground Fault Circuit Interrupter (GFCI) continuously compares the current flowing out on the hot conductor to the current returning on the neutral. In a healthy circuit they are equal. If there's a ground fault — current leaking through a person, a wet floor, or damaged insulation — the returning current is less than the outgoing current by at least 5 milliamps (0.005A). The GFCI detects this imbalance and trips in about 25 milliseconds, cutting power before enough current flows to cause ventricular fibrillation (which requires ~100mA).
A GFCI can be a receptacle (with TEST/RESET buttons) that also protects downstream outlets on the same circuit, or a GFCI breaker in the panel that protects the entire circuit. Both satisfy NEC 210.8.
NEC 210.8 — Where GFCI Is Required
The 2023 NEC requires GFCI protection for all 15A and 20A, 125V receptacles in:
- Bathrooms
- Garages and accessory buildings
- Outdoors (all exterior receptacles)
- Crawl spaces (at or below grade)
- Unfinished basements
- Kitchen receptacles within 6 ft of a sink
- Laundry areas
- Boathouses and pool areas
- Rooftop receptacles
- Boat hoists
GFCI protection is about moisture risk — anywhere water and electricity could meet.
What Is an AFCI — How It Works
An Arc Fault Circuit Interrupter (AFCI) uses digital signal processing to continuously monitor the circuit's electrical waveform for the signature patterns of arcing — the rapid current changes and high-frequency noise that parallel arcs and series arcs produce. It distinguishes between normal arcs (motor brushes, switches opening) and dangerous arcs (damaged insulation, loose connections, nail through a wire) and trips when it detects a hazardous arc.
AFCI protection must be provided by a breaker (or listed panel-level combination device) — a receptacle cannot provide AFCI protection. This matters when replacing circuits or adding outlets in AFCI-required locations.
NEC 210.12 — Where AFCI Is Required
Under the 2023 NEC, AFCI protection is required for all 120V, 15A and 20A branch circuits supplying outlets in dwelling unit:
- Bedrooms (required since 1999 NEC)
- Living rooms, parlors, libraries, dens, sunrooms
- Recreation rooms, closets, hallways
- Laundry areas
- Kitchens (added in the 2020 NEC)
- Dining rooms
- All similar dwelling unit rooms
AFCI is about arc-fault fire risk — anywhere energized conductors run through walls and ceilings in living spaces.
Dual-Function (Combination) GFCI/AFCI Breakers
Many circuits require both GFCI and AFCI protection — particularly kitchen, laundry, and garage circuits in newer NEC editions. A dual-function breaker provides both in a single panel slot, satisfying both NEC 210.8 and 210.12 simultaneously.
Dual-function breakers are more expensive (~$40–60 each vs. ~$10–25 for a standard breaker) but are the cleanest solution when both requirements apply. They're available from Square D (QO), Eaton (BR, CH), and Siemens for all common panel types.
Which Do You Need? — Quick Decision
| Location | GFCI | AFCI | Both (Dual) |
|---|---|---|---|
| Bathroom | ✅ Required | Depends (local AHJ) | Often recommended |
| Bedroom | — | ✅ Required | — |
| Kitchen (2020+ NEC) | ✅ Sink area | ✅ Required | ✅ Use dual |
| Laundry (2020+ NEC) | ✅ Required | ✅ Required | ✅ Use dual |
| Garage | ✅ Required | — | — |
| Living room / den | — | ✅ Required | — |
| Outdoors | ✅ Required | — | — |
Requirements vary by NEC edition adopted by local jurisdiction. Always verify with your local Authority Having Jurisdiction (AHJ).
Frequently Asked Questions
GFCI protects people from ground faults (shock, electrocution). AFCI protects property from arc-fault fires in wiring and devices. They detect completely different hazards and are often both required on the same circuit.
NEC 210.8 requires GFCI in bathrooms, garages, outdoors, kitchens (near sinks), crawl spaces, unfinished basements, laundry areas, pool areas, and other wet/damp locations.
NEC 210.12 requires AFCI in bedrooms (since 1999), and progressively more dwelling rooms with each NEC edition — now extending to kitchens, laundry, hallways, and most living areas in the 2020/2023 NEC.
Yes. A GFCI outlet satisfies NEC 210.8 for GFCI requirements. But for AFCI, you need a breaker — a receptacle cannot provide arc fault protection.
A combination breaker that provides both GFCI and AFCI protection in one device, satisfying both NEC 210.8 and 210.12. Required for circuits needing both (kitchen, laundry with 2020 NEC). Available from Eaton, Siemens, Square D.