AFCI — Arc Fault Circuit Interrupter
Also known as: Arc fault breakerAFCI breakerdual-function breaker (when combined with GFCI)AFCIArc fault circuit interrupterCombination AFCI
An AFCI is a special type of circuit breaker that detects the electrical signature of arcing — the tiny sparks that happen when a wire is damaged, a connection is loose, or insulation fails. Normal breakers only trip on overload (too much current) or short circuit (direct fault). AFCIs trip on patterns that indicate an arc fault, which is the cause of most residential electrical fires.
The NEC has steadily expanded AFCI requirements since 1999. The 2026 CEC requires AFCI protection on virtually every 15A and 20A 120V branch circuit serving dwelling unit areas — bedrooms, living rooms, kitchens, dining rooms, hallways, closets, laundry rooms, and similar.
When AFCI requirements first rolled out, they had a reputation for nuisance tripping — flagging normal motor inrush from vacuums or refrigerators as arc faults. The current generation of AFCI breakers (post-2014) is significantly better; nuisance tripping is rare but not zero.
When you upgrade a panel or add a new circuit, current code applies — meaning the new circuit gets AFCI protection regardless of what the rest of the house has. If you're upgrading a panel in an older house with no AFCI anywhere, you have two paths: upgrade only the circuits being modified (cheapest, code-compliant for the work being done) or upgrade everything to match (more expensive, dramatically reduces fire risk). We'll talk through both.
If your house was built before 2002 and you have the budget, upgrading the whole panel to AFCI/GFCI dual-function breakers during a panel replacement is the single best electrical safety investment you can make. Statistically, AFCIs prevent fires that the homeowner would otherwise never know were at risk.
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