July 29, 2015
What is the purpose of AFCI Technology in the Your Home?
Arc Fault Circuit Interrupters (AFCIs) are electrical safety devices and are
required by the Canadian Electrical Code (CE Code) for certain electrical
circuits in your home.
What are arc faults?
In simple terms, arcs are the passage of electric energy through the air. The
temperatures of these arcs can exceed 10,000 degrees Fahrenheit. The
most immediate danger from an uncontained and uncontrolled electrical arc
in your home is fire because the heat of the arc will ignite surrounding
materials.
The CSA Standard for AFCIs (CSA C22.2 No. 270) defines an arcing fault
as “an unintentional arcing condition in a circuit”. Arcing creates high intensity
heating at the point of the arc resulting in burning particles that may over time
ignite surrounding material, such as wood framing or insulation.
How is an arc fault detected?
An AFCI utilizes advanced electronic technology to “detect” the different
arcing conditions. While various AFCI manufacturers use different
technologies to measure arcs, the end result is the same, detecting arcing
faults in damaged wiring and turning off the circuit before a fire can start.
Note: Arcs can be classified as parallel (arcing between wires - line to line,
line to neutral and line to ground) or series (arcing along a single
broken or frayed wire, or at a loose connection).
How does arc fault detection work?
Arc fault detection is accomplished by the use of advanced electronic
technology to monitor the circuit for the presence of both “normal” and
“dangerous” arcing conditions.
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Some equipment in the home, such as a motor driven vacuum cleaner or
furnace motor or turning off a light switch naturally create arcs – and these
are accepted as normal.. Damaged wiring or loose connections will allow
dangerous arc faults to occur. The advanced electronics in AFCIs are smart
enough to sense the difference between a normal arc and a dangerous arc.
A dangerous arc, occurs for many reasons including damage of the electrical
wire, its insulation, a loose terminal as the building ages or a frayed or
pinched extension cord. The AFCI constantly monitors and analyses the
electrical circuit. When any arc occurs, the AFCI instantly assesses the
characteristics of the event and determines if it is a normal arc or a
dangerous arc. If it is a dangerous arc the AFCI turns off or de-energizes
the circuit to stop the arcing and related heating effect. If the arc was normal
the AFCI does nothing except wait to assess the next arc.
AFCI manufacturers test for the hundreds of possible operating conditions
and then program their devices to measure constantly for the normal and
dangerous arcing conditions.
Types of AFCIs
Arc Fault Circuit Interrupter (AFCI)
AFCIs are intended to mitigate the effects of arcing faults by functioning to
de-energize the circuit when an arc-fault is detected. AFCIs are required by
the CE Code to be “approved” products. This means that they must be
evaluated by a nationally recognized testing laboratory to the national
standard for AFCIs (CSA C22.2 No. 270). Rules 26-724(f) and (g) establish
the requirement to use AFCIs. Protection is required for branch circuits as
specified in these CE Code Rules.
Branch Feeder AFCI
An AFCI intended to be installed at the origin of a branch circuit in the
electrical panel. The Branch Feeder AFCI provides for detection of parallel
arcing faults that can occur line-to line, line to neutral and line to ground.
Branch Feeder technology is being phased out with the introduction of the
2015 CE Code Part 1.
July 29, 2015
Combination AFCI
Combination AFCI provides series arc detection in addition to the protection
provided by the Branch Feeder AFCI. . This series arc detection is beneficial
to detect lower level arcing in both branch circuits and appliance, lamp and
extension cords. The Combination AFCI protection requirement was
introduced to the new 2015 CE Code Part 1.
Outlet Branch-Circuit AFCI
The 2015 CE Code also allows Outlet Branch Circuit (OBC) AFCI devices
as an alternative solution to Combination AFCI circuit breakers, but the wires
must be protected by conduit or armoured cable from the electrical panel to
the first receptacle. They provide for detection of parallel and series arcing
faults and offer the benefits of localized TEST and RESET.
AFCI and GFCI Protection
An AFCI can be used in conjunction with GFCI protection, to provide arcing
fault protection as well as 5mA ground fault people protection from electric
shock. A common way to provide both types of protection is to use an AFCI
circuit breaker and a GFCI receptacle. Now AFCI's can also incorporate 5mA
GFCI protection into the same package. This solution for AFCI and GFCI on
the same circuit can be useful where the CE Code requires both types of
protection, and where the installer or user want to have both types of
protection.
What is the difference between a ground fault and an arcing fault?
A ground fault is when electricity “leaks” to ground via water, moisture or
some other method when an appliance or other electrical device is used and
can become a shock hazard. A ground fault circuit breaker or GFCI outlet is
designed to “sense” when that leakage is occurring and shut off the power
to the circuit or outlet.
An arc fault is an “arcing condition” that takes place when electricity is
"jumping" or “arcing” from one conductor to another due to damaged wiring,
either in the wall or on the electrical product’s power cords. These arcs have
July 29, 2015
the potential to initiate fires after repeated arcing events. The Arc Fault
Circuit Interrupter is designed to shut off the power when these events occur.
An AFCI does not replace a GFCI. They are two different technologies used
for different safety reasons even though both offer protection from electrical
hazards. When in doubt, contact a qualified electrician as to their application
and what is required by your local electrical Code. More information on the
subject of arc faults and arc fault interruption can be obtained at:…