Every year there are over 40,000 residential fires in the United States attributed to faulty electrical wiring. These fires take the lives of more than 350 men, women and children and injure over 1,200 others. The vast majority of these fires were caused by Arc Faults, an electrical fault that isn’t detected by or protected against by either a regular CB (Circuit Breaker) or fuse, or by a GFCI (Ground Fault Circuit Interrupter) CB.
Circuit breakers and fuses protect equipment and wiring against short circuits, a system fault where the hot conductor comes into direct contact with a grounded conductor or surface. GFCI breakers or receptacles protect human beings against potentially fatal shocks caused by a ground fault in the electrical system or utilization equipment attached to the wiring system. Ground faults occur when the neutral conductor, the grounded conductor, comes into contact with a grounding conductor or with a grounded surface. GFCI detects the unbalance in the current flow between the hot and neutral conductors and trips the circuit open. Neither a regular CB nor GFCI is designed to detect and respond to an “Arc Fault” condition.
Arc Faults are a condition that arises when there is a partial break in the circuit. This damage could occur when someone unknowingly drives a nail through a wire while hanging pictures, an extension cord is caught under a piece of furniture, or a lamp cord becomes frayed with age. Arc faults occurred when receptacles, light switches, lights or some other device is installed incorrectly. Arc faults can occur inside receptacles and switches when the internal contacts lose their tension with age. The arcing that occurs at these points generates a great deal of heat which can ignite any combustible materials in close enough proximity to it. Arc faults cause erratic current flow which is what the AFCI (Arc Fault Circuit Interrupter) detects and protects against. AFCI are designed to not trip out from normal arcing such as when a light switch is opened or closed or some energized device is unplugged.
The 1999 Revision of the NEC was the Code Revision that made AFCI mandatory protection on all residential bedroom branch circuits. Article 210.12(B) of the 2008 Revision of NEC expanded this requirement to include”…family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, and similar rooms and areas.” There are a few exception to this rule listed in the Codes FPNs (Fine Print Notes) but the safest way to go is to install AFCI breakers on all new circuits and to replace the standard CBs on already existing circuits with AFCI breakers.
AFCI units combine the function of a regular CB with an AFCI protective device in one unit. AFCI breakers like GFCI breakers should be tested regularly by depressing the test button on the breaker to simulate an Arc Fault condition. The breaker should trip out instantly.
To replace an old style CB with an AFCI breaker
Follow the detailed instructions provided with the breaker by the AFCI breaker manufacturer but the following steps is a good general outline of the steps involved
· Turn of the panel’s Main Breaker
· Remove the panel’s cover
· Disconnect the branch circuits hot conductor from the old breaker
· Disconnect the neutral conductor for that branch circuit from the panel’s neutral bar
· Remove the old breaker
· Install the AFCI breaker connecting the circuit’s hot conductor to the right screw and the circuit’s neutral conductor to the left screw.
· Connect the coiled white wire attached to the AFCI to the panel’s neutral bar.
· Turn the panel’s main breaker on
· Test the AFCI for proper operation.
This is the instruction sheet that comes with a GE 2-pole AFCI breaker that might be used to protect a split-wired (Multiwired) 110-volt receptacle circuit or a 220-volt branch circuit. The connections would be the same for a single-pole breaker except there will only be connections for one hot conductor instead of two.
