Electrical circuit-interrupters

Safety Tip

  • All AFCIs and GFCIs, whether circuit-type or breaker-type, should be installed by a qualified electrician.
  • Test AFCIs and GFCIs after installation and once a month thereafter to make sure they are working properly.
  • Replace defective AFCIs and GFCIs immediately. A defective device may create a false sense of security to those who do not know that it is non-functional.
  • Choose AFCIs and GFCIs that carry the label of an independent testing laboratory and always follow the manufacturer's instructions.

Protective devices capable of responding to overloads and short circuit, such as circuit breakers, have been available for a number of years. Newer technologies now provide enhanced protection from arcing or ground-faults, which may prevent fires or shock.

AFCIs (arc-fault circuit-interrupters)
When an electrical switch is opened or closed, an arc, or discharge of electricity across a circuit, occurs. Unintentional arcs can occur at loose connections or where wires or cords have been damaged. Such arcs can lead to high temperatures and sparking, possibly igniting combustibles. AFCIs (arc-fault circuit-interrupters) protect against fire by continuously monitoring the electrical current in a circuit and shutting off the circuit when unintended arcing occurs. These devices are designed to discriminate between unintended arcing and the type of arcing that occurs when a switch is operated.

GFCIs (ground-fault circuit-interrupters)
A ground-fault is an unintentional electrical path between a source of electrical current and a grounded surface. Electrical shock can occur if a person comes into contact with an energized part. GFCIs (ground-fault circuit-interrupters) can greatly reduce the risk of shock by immediately shutting off an electrical circuit when that circuit represents a shock hazard (i.e., a person comes in contact with a faulty appliance together with a grounded surface). GFCIs can be installed in a circuit breaker panelboard or directly in a receptacle outlet.

Facts and figures

  • AFCI installation is required by the National Electrical Code® (NEC) in bedrooms of new residential construction (effective as of January 1, 2002). Bedrooms were selected as the first area in which to implement this requirement because of a history of fires there.
  • GFCI installation is required by the NEC for receptacles in kitchens, bathrooms, outdoor areas, basements and garages in new residential construction because of a history of shock hazards in these areas.

AFCIs and the National Electrical Code

What are Arc-Fault Circuit Interrupters (AFCIs)?
The 2008 National Electrical Code® (NEC®) requirement for AFCI protection considerably expands this fire prevention technology to the majority of circuits installed in new and renovated homes. The type of AFCI currently available commercially is a next-generation circuit breaker that not only provides the conventional safety functions, but its advanced design also rapidly detects potentially dangerous arcs and disconnects power in the circuit before a fire can start. Fire safety officials throughout the United States endorse AFCIs as a significant step forward in electrical fire safety.

Why should they be installed in homes?
AFCIs will save lives and make homes safer. According to the U.S. Fire Administration, each year home electrical problems cause about 70,000 fires, resulting in 485 deaths and $868 million in property loss.

Why mandate AFCIs for newer homes when statistics show the majority of problems have occurred in older homes?
Fire safety officials recommend the use of AFCIs in all dwellings. While it is true that fire statistics in many cases are derived from older dwellings, damage to appliance cords or to wires hidden in a wall can occur regardless of the home’s age. In addition, incorrectly performed electrical installations can occur in both new and old homes. As technology evolves and the NEC is revised, the enhanced level of safety is typically required only in new construction that is subject to the latest adopted edition. Homes wired per the 2008 NEC will have the majority of their circuits protect by AFCIs for the life of the electrical system.

How do you know AFCIs will prevent fires and save lives?
Since 1999, AFCIs have been thoroughly field-tested. Underwriters Laboratories, the National Association of State Fire Marshals (NASFM), the U.S. Consumer Product Safety Commission, and many other experts have found AFCIs to be reliable and effective. By eliminating a significant source of electrically related fires, future statistics will demonstrate a reduction in fires of electrical origin.

Are AFCIs expensive?
The cost of the enhanced protection is directly related to the size of the dwelling and the number of circuits installed. Current retail prices of AFCI-type circuit breakers at several national building supply chains are in the range of $35 to $40 per unit. Even for larger homes with more circuits, the cost increase is insignificant compared to the total cost of the home, particularly when the increased level of safety is factored.

Do AFCIs interfere with smoke alarms and appliances, and trip unnecessarily?
AFCIs do not interfere with power supply reliability. These state-of-the-art devices identify problems that current circuit breakers are not designed to protect against, which can result in what appears to be an unexplained circuit breaker trip. By actually identifying these problems, residents are safer.

What is the NEC?
The NEC is the National Electrical Code. The NEC’s mission is to provide practical safeguards from the hazards that arise from using electricity. It is the most widely adopted safety code in the United States and the world, and it is the benchmark for safe electrical installations. The NEC is an evolving document, developed through an open consensus process. A new edition is issued every three years.

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