Arc Fault Prevention

Electrical wiring is to blame for over 40,000 homeJohn Servier Fossil Plant. As quoted by TVA
fires annually. High temperatures are producedspokesman Scott Brooks, a large electrical panel
creating risk of ignition of nearby wood, paper andcaught fire when a unit failed and began to arc.
carpets when an electrical arc fault occurs.An arc fault can occur because of damaged or
 There is no way to stop an appliance ordeteriorating wires and cords, yet such causes like
electronic device from shorting out, but the riskthe puncturing of the wire insulation due to picture
of an arc fault occurring can be reduced byhanging or cable staples, poorly installed outlets or
installing an Arc Fault Circuit Interrupter (AFCI). Answitches, cords caught in doors or under furniture,
AFCI stops all electric current when detectingfurniture pushed against plugs in an outlet, natural
change in the charge from hot to neutral.aging and cord exposure to heat vents and
Some electronics such as computers, microwavessunlight are also to blame.
and TV's are equipped with transformers thatThere are three types of arc fault circuit
hold power when not in use as long as it isinterrupters; branch/feeder AFCI, outlet circuit and
plugged into a receptacle receiving an electriccombination.
charge. If an arc fault circuit interrupter is in place,- Required by the National Electric Code, branch
the AFCI would trip the breaker stopping allfeeder AFCI's are installed within a panel board to
electricity to the device if shortage occurs.provide parallel arc protection of the branch or
Bedroom lamps are high on the list of householdfeeder circuit wiring. It also aids in the protection
items causing arc faults because of their lowof arcs in the cord sets and supply cords.
voltage shorting making it hard for a circuit- An outlet circuit AFCI is placed at a branch
breaker to recognize an abnormality in order tocircuit outlet providing protection against arcing
trip the breaker. In 2002, the National Electricwithin the cord sets and power supply cords
Code made it a requirement to have an arc faultplugged into an outlet. This specific AFCI does not
circuit interrupter installed on all bedroomprovide protection on feed-thru branch circuit
receptacle outlets. conductors.
In the case of Unit 4 of the Tennessee Valley- A combination AFCI is typically a receptacle
Authority power plant, an Arc Fault Circuitproviding protection downstream of the device
Interrupter would have prevented the fire causedfor branch circuit wiring, cord sets and power
on December 31, 2009 at the Rogersville, TN,supply cords.