AFCI (Arc Fault Circuit Interrupter) protection helps prevent residential electrical fires. Around 25,000+ home fires are reported each year with an estimated 280 deaths and 1,125 injuries according to the U.S. Fire Administration. Arc-fault protection is sometimes in the form of an outlet or a breaker with unique technology that senses the specific issues that arise just before a fire starts.
What are arc fault breakers?
Arc fault breakers look different than a standard breaker, characterized by a noticeable test button on the breaker. Arc fault breakers are also more sensitive than a standard breaker. The neutral wire on a standard breaker will terminate at the neutral bar in the breaker box and has no protection on it from any faults. With an arc fault breaker, the neutral wire from each circuit ties into the breaker so that it can read any faults on the neutral as well as the hot conductor. This wiring difference offers much better protection.
Arc fault protection was first written into the 1999 code book. This was done so that manufacturers could start producing them. It wasn’t until 2002 that we were first required to install them in bedrooms only. It has expanded over the years to include all interior 120 volt circuits.
How arc-fault protection works
When you have a load of X amps on the hot conductor while a circuit is in use, the corresponding neutral wire should have the same load of X amps. If there's a loose connection on the neutral wire somewhere in the circuit, this will cause the neutral load to vary from the hot. With a standard breaker, nothing would happen, but with an arc fault breaker, it will trip. I’ve seen outlets melt away because the neutral wires were loose. Since they had a standard breaker, nothing tripped. This example is the most common occurrence that an arc fault breaker will better protect your home.
Other scenarios that would make an arc fault trip is if a wire is slightly pinched in a wall and the neutral wire is touching the ground wire. This will also send some of that neutral load down the ground wire which isn’t designed to be energized. An arc fault breaker will read this and trip.
Some of the issues we run into when trying to retrofit an existing house that wasn’t wired for arc fault protection are shared neutral circuits and panels that are too small to accommodate arc fault breakers. In older homes built before the invention of arc fault protection, electricians would sometimes run a multiwire circuit from the panel to feed two different circuits. This wiring pattern would allow them to share one neutral wire between the two circuits. A standard arc fault breaker won’t work with a shared neutral. Some brands make a double pole arc fault breaker for this application, but they cost 3-4 times more than a standard and are hard to find.
Some panels that use tandem breakers, or thin breakers, simply don’t have the space to accommodate a full-size arc fault breaker. There is no tandem or thin arc fault breaker. In a panel fully loaded with thin or tandem breakers, we either have to replace the panel or look at installing arc fault receptacles.
There are two options for arc fault protection; one option is the previously discussed arc fault breakers, the other option is to install arc fault receptacles. These work very similar to GFCI receptacles; we install them at the first receptacle in the circuit, and they protect everything down the line from them on that same circuit. Please note that AFCI receptacles are not replacements for GFCI protection, but additions to GFCI protection. GFCI outlets and breakers are made to sense water and trip before anyone is harmed. For locations that need GFCI protection like bathrooms and kitchens, there are GFCI/Arc fault combination outlets and breakers.
Arc fault outlets will read the same faults and trip for the same reasons an arc fault breaker. In a shared neutral situation, we’ll have to find the start of both circuits and install a receptacle at each location. With the tandem or thin breaker scenario, we’ll have to locate the beginning of each circuit we are protecting and install a receptacle.
New home construction requires arc fault protection on nearly every 120-volt circuit within the home. Any remodel work where a circuit extends more than five feet also requires the addition of arc fault protection. If we are just replacing a breaker box for an upgrade, we are not required to install arc fault breakers on the existing circuits.
Every scenario is different and will require assessing the panel and number of circuits to determine what is the most cost effective way to properly arc fault protect your home. We do recommend arc fault protection as it will make your home a much safer place to live.
Arc Fault Protection
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