AFCIs – What You Need to Know

By: Jerry Durham | Oct 24, 2018

Arc Fault Circuit Interrupters (AFCIs) are an important electrical fire prevention and safety requirement of the National Electrical Code. With the changes to the NEC in 2017 there still seems to be questions regarding the use of AFCIs.  This primer will address these questions.

Section 210.12 requires that for dwelling units, all 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be protected by AFCIs.

So what does an AFCI actually protect?

AFCIs protect the entire circuit. This includes the electrical panel; the downstream wires that run through the walls; the outlets; the switches; all of the connections to those wires, outlets and switches; and anything that is plugged into any of those outlets and connected to switches on that circuit.

Nuisance Trips with AFCIs, True or False?

 It is well known that early AFCI’s were sensitive to arc simulations such as operating vacuum cleaners, mixers, etc.   These nuisance trips were very problematic as electrical contractors were forced to explain to customers why the devices were tripping.  This became a financial burden with repeated call backs to the job, as well as a safety issue when customers ended up taking the AFCIs out all together and replacing with standard breakers.

Today’s technology has improved greatly and there is much more acceptance all around.  There are times when an AFCI will trip and appear to be a nuisance trip when in reality it did pick up on a compromised circuit.

What are Combo AFCIs? 

The Combination Type AFCI differs from the Branch/Feeder AFCI in its ability to detect series arcing faults. The Branch/Feeder AFCI can only detect line-to-neutral and line-to-ground arcing faults. Combination AFCIs provide protection against the high-energy parallel (line-to-neutral and line-to-ground) arcing and low-energy series arcing. “Combination” does NOT mean an AFCI + GFCI. Combination = parallel + series arcing. Combination AFCIs protect downstream branch circuit wiring, cord sets, and power supply cords.

What about GFCI-AFCI Combo units?

 Dual Function Circuit Breakers combine Class-A 5mA GFCI and Combination Type AFCI technology, protecting against both Arc Faults and Ground Faults. The 2017 National Electrical Code (NEC®) requires both Arc Fault and Ground Fault protection on kitchen and laundry circuits. Before the release of Dual Function Circuit Breakers, the only option to comply with this code was to pair an AFCI circuit breaker with a GFCI receptacle. The Dual Function Circuit breaker combines these two devices into one.

Why have arc faults in the home become such a concern now?

AFCIs eliminate a significant source of electrically related fires. The National Fire Protection Association indicates future statistics on AFCIs will demonstrate a reduction in fires of electrical origin and the CPSC estimates more than 50% of electrical fires that occur every year can be prevented by AFCIs.

According to the U.S. Fire Administration, electrical issues within the home cause nearly 70,000 fires each year, contributing to 485 deaths as well as $868 million in property loss.

Thanks to AFCI protection, along with improved construction materials and other fire prevention technologies, the number of fires in the U.S. has dropped more than 20% since 2004, down to 1,240,000 in 2014, per the USFA.



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