Arc-Fault Circuit Interrupters (AFCIs) 

Electical Arc Solid State Home Inspections

Electricity is a very dangerous but essential service in our homes. As we enter our second century of wiring homes for electricity, electrical safety authorities have come up with many safety innovations including the newer safety device, Arc-Fault Circuit Interrupters (AFCI's).

What is an AFCI?

Arc-fault circuit interrupters, like the name implies, are devices that can detect the electronic signature of arcing electricity and shut down the effected circuit nearly instantly. This is important as when electricity flows through wires properly in our homes there is no observable signs of the electricity. If wiring becomes loose or damaged though electricity, like lightening, may try and leap across a gap in the wire creating visible light and huge amounts of heat. This heat can start structural fires and is what a AFCI is in place to detect and stop.

Fire authorities have identified arcing electricity is one of the leading causes of electrical home fires. Common causes of arcs in the home can be caused by: Damaged electrical cords (vacuum cords in particular take a lot of abuse), liquid spills, or loose connections in outlets, switches, and lights.

Doesn’t a Breaker or Fuse do the same thing as an AFCI?

Breakers and fuses are designed to monitor the total load on a circuit and to trip if the load is greater than the circuit wiring can handle. Electrical arcing and corresponding structural fires can happen at electricity levels below the tripping point of the breaker or fuse. AFCI’s are able to monitor electronic signals of arcing in the circuit at very low electricity levels and respond to those signals which makes them very beneficial in electrical fire prevention.

How is an AFCI Different than a GFCI?

Ground Fault Circuit Interrupters (GFCI's) are designed to prevent personal electrocution injuries by recognizing electricity leaks that could be from an electrocution in progress. AFCI’s primarily protect the home (and occupants) from structural fires. GFCI’s can appear similar to AFCI’s as both may be located in an electrical panel and both have a test button, however GFCI’s are typically in wet environments only. Your home inspector can help you identify which breakers with test buttons are AFCI's and which are GFCI's. For more information on GFCI's, see our home inspection article on GFCI’s here.

What Circuits in a Home are Protected by AFCI’s?

The earliest use of AFCI’s has been in bedrooms based on the logic that we are most vulnerable to fires started in bedrooms as we may be sleeping when the fire starts, and that we may not be able to exit quickly and safely once the fire has been detected. National electric codes in both Canada and the USA now call for AFCI’s to be installed in all bedrooms although not all municipals have adopted all the national codes. Home inspectors cannot check for code compliance but should identify and test AFCI’s if they are found in a home inspection.

The electrical safety authorities have recognized that AFCI’s can be beneficial in other locations in the home however we don’t yet commonly find AFCI’s in home inspections outside of bedroom circuits. 

Where do I find an AFCI Device?

Breaker Style AFCI

Clearly labeled as AFCI with blue test button.

AFCI devices are typically built into the breakers on the bedroom circuits in the electrical panel. They are labelled with ‘AFCI’ and there is a test button on the breaker. Home inspectors can identify these AFCI’s and should test them to ensure they work correctly. This may be a nuisance for home occupants as clocks and other devices plugged into bedroom outlets may need resetting but the importance of testing life safety features for the home inspection client should outweigh the nuisance to the occupant. Home occupants should test AFCI’s monthly when they test GFCI’s.

There are outlet based AFCI's available but these are not commonly found in home inspections or used yet in new house installations. This may be as they could be hidden behind furniture making it difficult to test, reset after tripping, and inspect.

Nuisance Tripping and AFCI’s

AFCI’s are an excellent layer of safety protection in the home but like smoke detectors near kitchens, they can be tripped by false alarms. Devices with motors such as fridges, freezers, and air conditioners have been known to trip AFCI’s if wiring or grounding systems are not in good working order. This is another reason AFCI’s have been installed early on in bedrooms as these circuits are unlikely to have fridges or freezers where food may spoil if the circuit is tripped. It is easy to reset a tripped circuit and your home inspector should show you this during your home inspection.

Final Thoughts

AFCI’s can be retro fitted into existing bedroom circuits and is an excellent improvement to the safety features of any home. As always with electricity, leave it up to professionals like home inspectors or electricians to inspect your home and only allow licensed electricians to perform any changes to your electrical system.

By James Bell - Owner/Operator of Solid State Inspections Inc.