Arc-Fault Circuit Interrupters (AFCIs)

Most of my clients for home cottage and commercial inspections in Orillia, Gravenhurst, Bracebridge,and Muskoka area are well aware of GFCI outlets and breakers and that they protect them from shocks but few are aware of what the newer AFCI or Arc Fault Circuit Interupter breakers do. Arc-fault circuit interrupters (AFCIs) are a different type of circuit breaker designed to detect and trip when dangerous electrical arcs occur in home branch circuits.

AFCI breakers constantly monitor the power

AFCIs work by monitoring  electrical waveforms for a pattern  that matches a dangerous arc and tripping the breaker if they detect those changes. They have to distinguish a safe normal arcs, like a plug being pulled from a receptacle or a switch being turned on, from arcs that can cause fires.  AFCI breakers trip by sensing  and recognizing very small changes in wave patterns.

Its the arc that creates the heat

When electric current crosses an air gap from a power source to a grounded element it produces a glowing plasma discharge known as an arc. This the basic principal behind Arc wielding. And like arcs produced by a wielder to heat and fuse steel, home wiring that is arcing can produce very high levels of heat that will ignite their surroundings leading to residential fires.

Although short-circuits and overloaded circuits account for many home fires, arcs are responsible for the majority and they are not detected by standard circuit breakers.

Several situations cause arcs 

Arcs begin from connections being improperly made and from wires installed  incorrectly. Arcs can start when insulation becomes damaged and in older homes wire insulation tends to crystallize as it ages becoming brittle. Any renovations in an area with brittle insulation can easily crack and chip it. Damaged insulation makes it possible exposed power carrying wire can arc to surrounding metals, nails in rafters or trusses , electrical  fixtures or boxes etc. Loose connections in outlets, switches and light fixtures, damaged electrical cords, nails and screws used in hanging pictures or art work,  and just old age can all cause arcing.

Other things can cause tripping AFCI breakers

AFCI breakers can trip and create needless power shortages.  There are several things for an  electrical contractor to check to reduce potential nuisance tripping.  The load power wire, panel neutral wire and load neutral wire should be checked to ensure they are properly connected.  The wiring  should be checked for shared neutral connections which need correction, and the junction box and fixture connections can be checked to be sure that the neutral conductor contacts a grounded conductor.

Where and when are Arc Fault Circuit Interrupters (Breakers) required

Building codes in Orillia, Gravenhurst, Bracebridge, and all Muskoka where Done Right Home Inspections serve our clients require AFCI's be installed in bedrooms of all new homes and in renovations to existing homes in bedrooms only. Essentially, all newly created or newly renovated bedrooms must have all branch circuits ( that supply120-volt, single-phase, 15- and 20-amp outlets installed in them)  protected by a combination-type or branch/feeder-type arc-fault circuit interrupter installed to provide protection of the entire branch circuit.

There are other types of AFCI protection available than the Branch/feeder—installed at the main electrical panel or sub-panel. This is the most commonly seen AFCI protection seen in the Orillia, Gravenhurst, Bracebridge, Muskoka areas but you can also get an outlet circuit AFCI which is installed in a branch-circuit outlet box.    

The difference between Arc Fault and Ground Fault devices

It is important to note the difference between AFCI devices and Ground Fault Circuit Interrupter (GFCI) devices. GFCIs detect ground faults,  this is a fault which occurs when current leaks from a hot and ungrounded conductor, to a grounded object  (possibly you ) as a result of a short-circuit.  GFCIs work by constantly monitoring the current flow between hot and neutral, or grounding, conductors. GFCI's activate when they sense a difference of 5 milliamps or more.  

GFCIs help to prevent personal injury due to electric shock.  AFCIs help prevent personal injury and property damage due to fires.

It is easy to tell the difference when I am doing a home cottage or commercial inspection as AFCI breakers all have the white pigtail to connect them to the neutral buss. GFCI`s do not have a pigtail.  My clients in Orillia, Gravenhurst, Bracebridge, and all Muskoka know I will be looking for both GFCI`s and AFCI`s because it`s my job to make sure they are protected and if not, I then inform them of the facts about Arc Fault Circuit Interrupters.