An arc-fault circuit interrupter, usually called an AFCI, is a safety device designed to recognize electrical arcing that can start a fire. AFCI protection is commonly built into a breaker at the electrical panel, but its purpose and behavior are different from both a standard breaker and a GFCI.
What is an electrical arc fault?
Arcing occurs when electrical current crosses an unintended gap or damaged connection. Cracked insulation, damaged cords, loose connections, and injured wiring can create arcing and sparking conditions. If nearby material can burn, that heat can become a fire hazard.
What an AFCI is designed to do
The U.S. Consumer Product Safety Commission explains that ordinary fuses and circuit breakers may not respond to early arcing conditions. An AFCI monitors the circuit for characteristics associated with a hazardous arc and opens the circuit when it detects one, adding protection against wiring-related fire hazards.
AFCI, GFCI, and standard breakers have different jobs
A standard breaker protects circuit wiring from overloads and short circuits. An AFCI is intended to address fire hazards from arcing. A GFCI is intended to reduce the risk of serious electrical shock when current leaves its intended path. Some devices combine AFCI and GFCI functions, but the terms are not interchangeable.
- Standard breaker: overcurrent and short-circuit protection
- AFCI: protection from hazardous arcing conditions
- GFCI: protection from ground-fault shock hazards
- Dual-function device: AFCI and GFCI protection in one breaker
How to identify an AFCI breaker
An AFCI breaker normally has a TEST button and labeling that identifies its protective function. Dual-function breakers are labeled for both AFCI and GFCI protection. Panel designs and breaker markings vary, so use the manufacturer’s instructions for the exact device rather than relying on color or button position alone.
How to test installed AFCI protection
CPSC’s home electrical safety checklist recommends testing AFCI breakers periodically. Follow the instructions printed on the breaker or supplied by its manufacturer. A functioning test should cause the breaker to trip; reset it only as directed. If the test button does not trip the breaker, or the breaker will not reset, arrange an evaluation by a qualified electrician.
Why an AFCI breaker may trip
A trip means the device detected a condition it was designed to respond to, but it does not identify the cause by itself. The source may be fixed wiring, a receptacle or switch connection, a cord, or equipment plugged into the circuit. Repeated resetting can hide a developing problem instead of solving it.
- A damaged or pinched cord
- Loose or deteriorated wiring connections
- Insulation damaged by a fastener or physical wear
- A faulty appliance or other connected equipment
- A worn, incompatible, or defective protective device
What to do after an unexplained trip
Turn off or unplug portable equipment on the affected circuit if you can do so safely, then follow the breaker manufacturer’s reset instructions once. If the AFCI trips again, will not reset, or is associated with heat, odor, buzzing, sparking, or visible damage, leave the circuit off and call an electrician. Do not remove the panel cover or attempt to replace a breaker yourself.
AFCI requirements depend on the project
The protection required for new wiring, a remodel, or a panel change depends on the electrical code and local rules that apply to the work. Idaho’s Division of Occupational and Professional Licenses states that electrical work requires permitting and that jurisdiction varies because some cities and counties administer their own programs. Confirm the applicable requirements before installation.
When to have the circuit evaluated
Professional troubleshooting is appropriate when an AFCI fails its test, trips repeatedly, affects important equipment, or begins tripping after new work or a change in appliance use. Walker Electric can trace residential circuit problems, inspect visible connections and devices, and explain the appropriate repair or upgrade for Treasure Valley homes.