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Two single pole 20 amp Cutler Hammer Type CH Arc Fault Circuit Interrupter circuit breakers in a load center

Arc Fault Circuit Interrupters

Dear Mr. Electrician: What is the reason for Arc Fault Circuit Interrupter (AFCI) type circuit breakers? Answer: Arc Fault Circuit Interrupter type circuit breakers and receptacles provide an additional level of protection against fires.  Electrical arcs create heat and sparks.  If combustible materials are nearby, a fire could erupt.  Arc Fault Circuit Interrupter circuit breakers protect us from potential fire starters that we cannot see. Many residential homes have wood frame construction.  The electrical switch and receptacle boxes in the walls are attached to wood framing members.  The electrical wiring runs through the wood framing. Wood is a combustible material.  NOTE: Some text links below go to applicable products on Amazon.com A Series Arc or low current arc can be as a result of frayed power cords, old appliances, or loose electrical connections. A Parallel Arc or high current arc can occur from a screw or nail being partially driven into a live wire causing a poor connection to be made between two current carrying conductors.  Also known as a line-to-neutral arc. Line-To Ground Arc or ground fault indicates electrical current leaking to earth ground. A combination AFCI will protect against the three types of arcs. Causes of Electrical Arc Faults An electrical arc can be caused by lightning of course and your grounding electrode system, if it is in good condition, should handle that.  However other causes of arcing are usually not as obvious until some damage or a fire takes place.  For instance, an electrical receptacle with a loose connection may be fine until one winter you decide to plug an electric heater into it. The heater uses a lot of current to keep you warm.  With the extra LOAD on it, the loose connection that was fine for a few years now arcs each time the heater is on.  Arcing creates heat and sparks which can cause damage to the electrical receptacle, the wiring in the electrical box and wall, and even the heater plug.  In addition, the potential for fire is high.  If combustible materials are nearby such as drapes and curtains, bedding or even furniture, a fire can start whether you are home or not. Other Issues That Can Cause Arc Faults and Heat - Loose or broken plugs or cords on appliances and lamps. - Nicks in the house wires and/or the wire insulation that occurred during the original        construction or a renovation thereafter.  Even a nail driven into the wall to hang a painting can nick a wire. - Worn out electrical receptacles that do not hold the plugs in tightly. - Frayed insulation on appliances and lamps. - Worn electrical switches. - Very old electrically powered tools and appliances where the internal electrical insulation has degraded. Another possibility for wiring getting damaged is from a major redecoration or renovation project where the old existing wiring is disturbed.  A small unnoticed problem that occurred during the original renovation may not manifest itself into a major hazard until months or years later.  Existing wiring is best left alone in older houses. Like everything else in a house, wiring...