How to Determine when to Use Arc Fault Circuit Interrupters is one of the topics discussed in the DoItYourself.com community.

An arcs-fault circuit interrupter (AFCI) is a circuit breaker that breaks the circuit when it discovers the electric arcs that are a signature of loose connections in home wiring.Over time, loose connections can become hot enough to cause house fires.An AFCI distinguishes between a harmless arc and a potentially dangerous one, for example, in a lamp cord with a broken conductor.

Since the beginning of the 21st century, the electrical codes of Canada and the United States have required the protection of most residential outlets.Adoption is slower in parts of the world where the higher voltage means lower currents, specifically Western Europe and the UK, and their use is optional, except in high risk cases.

Residential electrical fires are one of the leading causes in the US.Over 40,000 fires are caused by home electrical wiring in the United States each year.Over 350 deaths and 1,400 injuries are caused by these fires each year.[5]

Conventional circuit breakers only respond to overloads and short circuits, so they don't protect against arcs that produce erratic, and often reduced current.Arcing faults in the home electrical wiring can cause fires.The current is continuously monitored by the AFCI circuitry.The potential for a fire to occur is reduced when the AFCI opens its internal contacts.[6]

The electronics inside an AFCI breaker can detect electrical currents that are associated with wire arcs, which are sustained for more than a few milliseconds.A combination AFCI breaker provides protection against parallel and series arcs, as well as ground and overload protection.If dangerous arcs are detected, the circuit will be opened.

When installed as the first outlet on a branch circuit, AFCI receptacles provide protection for the entire circuit.They provide parallel protection for the branch circuit.Regardless of the panel, the AFCI receptacle can be used on any wiring system.

The 1999 and 2002 versions of the National Electrical Code in the United States and the Canadian electrical code in Canada require the use of AFCIs in all circuits that feed outlets in bedrooms of dwelling units.All branch circuits supplying outlets or devices installed in dwelling unit kitchens are required to have AFCI protection.They are required in dormitory units as well.This requirement can be accomplished by using a "combination type" breaker, which is a specific kind of circuit-breaker, in the breaker panel that provides combined arcs-fault and overcurrent protection.It is important to check local code requirements because not all U.S. jurisdictions have adopted the NEC's requirements.

The purpose of the AFCI is to prevent fire.The Canadian Electrical Code uses different terminology but the same technical requirements for the "branch" and "combination" types of circuit breakers.A branch type AFCI travels 75 amperes of current from the line wire to either the neutral or ground wire.Branch type performance can be improved with a combination type.The combination type trips on 5 amperes.

There is an alternative solution to the AFCI breakers.There are dangers associated with parallel and series arcs.The ability to test and reset with buttons located on the face of the device is offered by the AFCI receptacles.This can save a journey to the breaker panel but can also encourage resetting by a user without investigating the underlying fault, as would presumably happen if someone with access to an electrical panel was notified.

In 2002, the NEC removed the word "receptacle" and left "outlets", with the effect that lights and other wired-in devices such as ceiling fans within bedrooms were added to the requirement.The 2005 code made it clear that all outlets must be protected, despite the discussion in the code-making panel about not including bedroom smoke detectors.The NEC defines "outlets" to include receptacles, light fixture and smoke alarms.An outlet is any point where AC electricity is used to power something.

The NEC requirement only applies to "combination type" AFCIs.The 2008 NEC requires the installation of combination-type AFCIs in all 15 and 20 ampere residential circuits with the exception of laundries, kitchens, bathrooms, garages, and unfinished basements.The NEC added kitchens and laundry rooms to the list of rooms requiring protection.[7]

The first edition of the Wiring Regulations in the UK indicates if the design has a high risk of fire from arcs.The method of testing is not described in the annexes, but the correct operation must be verified before completion.RCDs require a number of trip times at different fault current levels to be verified.[8]

Elderly care homes, community centres and kindergartens are examples of places that the German Wiring rules recommend for high risk situations.

It is designed to protect against fires caused by electrical arcs.While the sensitivity of the AFCIs helps in the detection of arcs, they can also indicate false positives by identifying normal circuit behaviors as arcs.Some vacuum cleaners and some laser printers trip as a result of lightning strikes.The effectiveness of AFCIs is reduced by nuisance tripping.There is research being done in this area.[9]

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