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)
AFCI vs CAFCI — what the C actually means
CAFCI is not "AFCI plus GFCI." That's the misconception the name invites, so let's kill it first: the "combination" in Combination AFCI refers to combining two kinds of arc detection — it has nothing to do with ground-fault protection. The breaker that combines AFCI and GFCI in one body is the dual-function (DFCI) breaker, covered above.
Here's the actual history. The first generation of AFCIs (branch/feeder type, 1999-2008) could only detect parallel arcs — current jumping between two conductors, like a nail through a cable. They were blind to series arcs — current arcing across a break in a single conductor, which is exactly what a frayed lamp cord or a loose backstab connection produces. A combination-type AFCI (CAFCI) detects both parallel and series arcs.
The practical upshot for your panel:
- Every AFCI breaker sold new today is a CAFCI. NEC 210.12 has required combination-type devices since 2008, so if you buy an "AFCI breaker" at the supply house, you're buying a CAFCI — the terms are interchangeable on modern stock.
- If your panel has pre-2008 branch/feeder AFCIs, upgrading to CAFCI gets you real protection you don't currently have (series-arc detection covers the most common failure mode: damaged cords and loose terminations) — plus far better nuisance-trip immunity.
- Need arc AND ground-fault protection on one circuit? That's the DFCI, not the CAFCI. Kitchen and laundry circuits typically land here.
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.
What's the difference between AFCI and CAFCI?
CAFCI (Combination AFCI) detects both parallel arcs and series arcs; the original branch/feeder AFCI only caught parallel arcs. The "combination" does NOT mean AFCI+GFCI — that's a dual-function (DFCI) breaker. Every AFCI sold new since 2008 is a CAFCI.
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.