AFCI (Arc Fault Circuit Interrupter)
A breaker or outlet that detects the electrical signature of dangerous arcing (loose connections, damaged wires) and cuts power before the arc starts a fire.
Arcing is electricity jumping a gap: a nail through a cable, a loose wirenut, a cord pinched by a couch leg. Arcs run thousands of degrees and are a leading cause of electrical fires, yet they draw too little current to trip a standard breaker. AFCIs analyze the current waveform and trip on the arc signature itself. Code has required them on most living-area circuits in new construction since the 2000s, expanding with each cycle.
AFCIs also have a reputation for nuisance tripping, and the truth is in the middle: some trips are compatibility quirks with certain electronics, but many "nuisance" trips are real arcs at loose backstabbed connections. An AFCI that keeps tripping deserves diagnosis, not removal: swapping it for a standard breaker silences the smoke alarm logic of the circuit.
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- Electrical Panel (Breaker Box) : The gray metal box where utility power enters your home and splits into individual protected circuits.
- Main Breaker : The single large breaker at the top of your panel that can disconnect the entire house, and whose rating (100, 150, 200 amps) defines your service size.
- Subpanel : A secondary breaker panel fed from the main panel, used to add circuit capacity or put breakers closer to where the power is used: garages, shops, additions, ADUs.
- Bus Bar : The rigid metal bars inside a panel that distribute power to the breakers.