Green Valley Home Inspections

Arc-Fault Circuit Interrupters (AFCIs)

Posted in Uncategorized by Administrator on the May 7th, 2014

Arc-fault circuit interruptersĀ  (AFCIs) are special types of electrical receptacles or outlets and circuit breakers designed to detect and respond to
potentially dangerous electrical arcs in home branch wiring.


How do they work?
AFCIs function by monitoring the electrical waveform and promptly opening (interrupting) the circuit they serve if they detect changes in the wave
pattern that are characteristic of a dangerous arc. They also must be capable of distinguishing safe, normal arcs (such as those created when a switch is turned on or a plug is pulled from a receptacle) from arcs that can cause fires. An AFCI can detect, recognize and
respond to very small changes in wave pattern.


What is an arc?
-When an electric current crosses an air gap from an energized component to a grounded component, it
produces a glowing plasma discharge known as an arc. For example, a bolt of lightning is a very large,
powerful arc that crosses an atmospheric gap from an electrically charged cloud to the ground or
another cloud. Just as lightning can cause fires, arcs produced by domestic wiring are capable of
producing high levels of heat that can ignite their surroundings and lead to structure fires.


Where are arcs likely to form?
Arcs can form where wires are improperly installed or when insulation becomes damaged. In older
homes, wire insulation tends to crystallize as it ages, becoming brittle and prone to cracking and
chipping. Damaged insulation exposes the current-carrying wire to its surroundings, increasing the
chances that an arc may occur.
Situations in which arcs may be created:
electrical cords damaged by vacuum cleaners or trapped beneath furniture or doors.
damage to wire insulation from nails or screws driven through walls.
appliance cords damaged by heat, natural aging, kinking, impact, or over-extension.
spillage of liquid.
Loose connections in outlets, switches and light fixtures


Where are AFCIs required?
Locations in which AFCIs are required depend on the building codes adopted by their jurisdiction. The 2006 International Residential Code (IRC) requires that AFCIs be installed within bedrooms in the following manner: E3802.12 Arc-Fault Protection of Bedroom Outlets. All branch circuits that supply120-volt, single-phase, 15- and 20-amp outlets installed in bedrooms shall be protected by a combination-type or
branch/feeder-type arc-fault circuit interrupter installed to provide protection of the entire branch circuit.




Green Valley Home Inspections

Serving Rancho Cucamonga, Upland, Riverside, San Bernardino, Los Angeles, Corona and the rest of Southern California


Eric Richards

Certified Master Inspector

President of Inland Empire Chapter of InerNACHI




Leave a Reply