The Ins and Outs of AFCI Protection

The arc-fault circuit-interrupter (AFCI) has been around for three National Electrical Code (NEC) cycles and, with the advent of the new 2005 NEC, will have been present in three editions, although with various changes within each edition. However, there are still questions concerning how and where to apply these devices in the field. While this article will try to address many of the common applications, there will undoubtedly be others that will be very unique and must be dealt with by installers and inspectors on an individual basis.

An arc-fault circuit-interrupter is a device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected. These devices were tested using almost every possible appliance, motor, or situation where limited arcing from normal use would occur to ensure that arcing from a non-fault situation would not provide nuisance tripping.

With one of the largest audiences to witness a Panel discussion on particular subject in NEC history, AFCI protection was inserted into the 1999 NEC by Panel 2 in new Section 210-12 with an effective date of Jan. 1, 2002. Since the 2002 NEC became an effective standard of Aug. 2, 2001, and the effective date for AFCI protection was Jan. 1, 2002, this placed the effective date for the AFCI requirement after the new 2002 NEC was issued. Many states, municipalities and counties do not adopt the newest NEC immediately, so this effective date permitted AFCI protection to be eased into use for a very limited application for dwelling unit bedroom receptacle circuits.

Arc-fault circuit-interrupter protection was limited to all branch circuits supplying 125V, single-phase, 15 and 20A receptacle outlets installed in dwelling unit bedrooms. No other circuits within a dwelling, other than those supplying receptacles in a bedroom were required to have AFCI protection. This made it very easy to determine where an AFCI was required.

If the circuit entered the dwelling unit bedroom to supply receptacles, then AFCI protection was required. If the circuit supplied only non-receptacle loads in a bedroom of a dwelling unit, then AFCI protection was not required. If a circuit supplied both lighting and receptacles in a dwelling unit bedroom, then AFCI protection was required. Receptacles, for example, in a bathroom connected to a bedroom did not require AFCI protection since the receptacles were not in the bedroom and 210-11(A)(3) did not permit any other outlets on the bathroom receptacle circuit so supplying a receptacle in the bedroom was a violation.

The 2002 NEC dropped the effective date of Jan. 1, 2002, and made a very major change to 210.12 by deleting the word “receptacle” before “outlets” so the text now is as follows: “All branch circuits that supply 125V, single-phase, 15 and 20A outlets installed in dwelling unit bedrooms shall be protected by an arc-fault circuit-interrupter listed to provide protection of the entire branch circuit.”

Eliminating the word “receptacle” meant that all 125V, single-phase, 15 and 20A branch circuits supplying outlets (loads) in a dwelling unit bedroom must have AFCI protection. Although always intended as protection of the entire branch circuit, the new text in the 2002 NEC also clarified that AFCI protection was intended to apply to the entire branch circuit, since arcing faults could occur in the wiring within the walls or ceilings.

With this new change applying to all 125V, single-phase, 15 and 20A outlets within a dwelling unit bedroom, determining where AFCI protection applied was not as simple and easy to accomplish. Branch circuits for smoke detectors, small window air conditioners, ceiling paddle fans, refrigerators, heaters, and lighting units (luminaires), as well as other outlets throughout the bedroom, were now required to be AFCI protected. Questions were raised about whether luminaires in walk-in closets required AFCI protection, which were easily answered by supplying it from a bedroom circuit already AFCI protected. Since switches are devices, not outlets, a switch located in a bedroom but supplying luminaire(s) located outside the bedroom area, such as security lighting or for bathroom lighting, would not require AFCI protection.

A more difficult question to answer, however, was whether a fire/burglar alarm panel located in a bedroom or in a walk-in closet was required to be protected by an AFCI circuit since the panel is an outlet. What would be the ramification of an arcing fault that disabled the 15 or 20A, 125V power circuit supplying a fire alarm panel with standby battery power for 24-hours where a family was gone over a weekend resulting in no fire alarm protection and no trouble signal to indicate loss of power?

These and other questions will be addressed in future articles dealing with the 2005 NEC. EC

ODE is a staff engineering associate at Underwriters Laboratories Inc., in Research Triangle Park, N.C. He can be reached at 919.549.1726 or at




About the Author

Mark C. Ode

Fire/Life Safety Columnist and Code Contributor
Mark C. Ode is a lead engineering associate for Energy & Power Technologies at Underwriters Laboratories Inc. and can be reached at 919.949.2576 and .

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