DIY Dictionary: Arc Fault Circuit Interrupter

An arc fault circuit interrupter (AFCI) is a device that ‘trips’ or shuts down power to a circuit when it detects electrical arcing.

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What is an Arc Fault Circuit Interrupter?

An arc fault circuit interrupter (AFCI) is a device that “trips” or shuts down power to a circuit when it detects electrical arcing. Common causes of arcing include faulty and frayed lamp and appliance cords, faulty or overheated extension cords, loose connections in outlets, switches and light fixtures or even a nail inadvertently driven into a wire. How common is this? An estimated 40,000 fires a year are attributed to faulty wiring, resulting in over 300 deaths and 1,500 injuries. It’s important to learn how to diagnose and fix an arc fault circuit interrupter problem.

The AFCI protection can be in the form of a special circuit breaker in the breaker panel or a special AFCI receptacle. Generally, when an AFCI receptacle is installed as the first outlet in a circuit, those downstream are likewise protected. AFCI devices have been around since the late 1990s and the National Electrical Code has increasingly mandated their use; now (for new home construction and remodeling) they’re required in most living areas. Existing residential wiring isn’t impacted by the code—but it’s not a bad idea to upgrade circuits when you remodel, or for safety’s sake. Plus: Learn how circuit breakers work.

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