Side by side
| Feature | AFCI | GFCI | Dual-Function (DFCI) |
|---|---|---|---|
| What it catches | Arc faults (high-frequency electrical sparking) | Ground faults (current to ground via person) | Both |
| What it prevents | Fires | Electrocution | Both |
| Trip threshold | Arc signature pattern | 4-6 mA leakage | Arc + ground fault |
| Trip time | ~50 ms on arc | <25 ms (UL 943) | Same as each individually |
| NEC code | 210.12 (1999+, expanded each cycle) | 210.8 (1971+, expanded each cycle) | Where both required |
| Required locations | Most living-space 120V circuits | Kitchen, bath, laundry, garage, outdoor, basement, near water | Where both apply (kitchens, laundry) |
| Cost | $40-$55 breaker | $35-$50 breaker / $20 outlet | $50-$70 breaker |
Where NEC requires each (current code)
AFCI required (NEC 210.12)
Most 120V, 15A and 20A dwelling-unit branch circuits supplying outlets or devices in:
- Kitchens, dining rooms, living rooms, parlors, libraries, dens, sunrooms, family rooms, recreation rooms
- Bedrooms (the original 1999 requirement)
- Hallways, closets
- Laundry areas
- Similar rooms (the code's catch-all)
GFCI required (NEC 210.8)
- All bathroom receptacles
- Kitchen receptacles (NEC 2020+ extended to all kitchen receptacles, not just counter)
- Laundry/utility sinks
- All outdoor receptacles
- Garage receptacles
- Unfinished basement receptacles
- Within 6 ft of sink/tub/shower
- Dishwashers (NEC 2014+)
BOTH required (use a DFCI breaker)
- Kitchen receptacles (kitchen falls under both 210.8 GFCI and 210.12 AFCI)
- Laundry rooms (same reason)
- Many basement layouts (per 2017+ interpretation)
The nuisance-trip problem
First-gen AFCIs (2002-2008) had high false-trip rates with universal motors (vacuums, hair dryers, power tools), variable-speed appliances, and dimmers. If you have an older AFCI tripping with no real fault, upgrade to current-gen CAFCI (Combination AFCI, post-2008) or DFCI. The current generation is far better at distinguishing motor brush-sparking from real arc faults.
A persistent nuisance trip on a new CAFCI/DFCI is telling you something real. Don't bypass it. Investigate:
- Damaged extension cord on the circuit
- Loose backstab connection at an outlet
- Pinched cable in a stud cavity (often from drywall screws)
- Aging appliance with arcing brushes
FAQ
What's the difference between AFCI and GFCI?
AFCI catches arc faults (fires). GFCI catches ground faults (electrocution). Different threats, different mechanisms.
Do I need AFCI and GFCI in the same outlet?
Yes in many locations per current NEC — kitchens, laundry, dishwashers. Dual-function (DFCI) breaker is the clean solution.
Why do AFCI breakers trip on vacuum cleaners?
Universal motors in older vacuums produce brush sparking that looks like arc-fault signatures. First-gen AFCIs (2002-2008) high false-trip rates. Current-gen CAFCI / DFCI much better.
Which NEC code requires AFCI?
NEC 210.12 — expanded every code cycle since 1999. Most 120V 15A/20A dwelling-unit branch circuits.
Are dual-function breakers more expensive?
Standard $5-$10. GFCI $35-$50. AFCI $40-$55. DFCI $50-$70. Worth it when code requires both.
Related guides
- How to test a GFCI outlet — monthly trip-time verification
- Best home electrical tester kits 2026 — Klein RT310 tests both AFCI and GFCI
- Best whole-house surge protectors 2026 — separate fire-protection layer at the panel
Editorial standards: Cited authorities include NEC 210.8 (GFCI required locations), NEC 210.12 (AFCI required locations), UL 943 (GFCI trip-time spec). Reviewed by Al, Building Doctor — 18 years Class A commercial electrical.