The NEC ® and UL ® Standard
2008 NEC ® AFCI Code Language
2008 NEC ® AFCI Applications in the Home
National Electrical Code
The National Electrical Code specifically defines and mandates the installation of AFCIs. In the 1999 edition of the NEC®, Section 210.12 required that dwelling unit bedrooms have AFCIs installed to protect all branch circuits that supply 125-volt, single-phase, 15 and 20-ampere receptacle outlets installed in the dwelling unit bedrooms. This requirement became effective January 1, 2002.
In the 2002 edition, the update of section 210.12 on expanded AFCI protection to all bedroom outlets (lighting, receptacle, smoke alarm, etc.).
The 2005 NEC 210.12 expanded the AFCI requirement to provide for a technology upgrade. While previous generations of product detected parallel arcing, this new device – a combination AFCI – would also detect series arcing, and at lower current levels.
Product standards to cover AFCIs began to be developed in the mid 1990's. Underwriters Laboratories published UL 1699 - Standard for Safety for AFCIs - in 1996 to cover a wide variety of conditions to evaluate an AFCI. The standard includes requirements for the follow conditions:
• Humidity Conditioning
• Leakage Current
• Voltage Surge
One of the most frequent questions about AFCIs is related to resistance to unwanted tripping.
There are four varieties of tests the UL standard specifies for unwanted tripping:
• Inrush Current: High current draw devices such as tungsten filament lamps and capacitor start motors.
• Normal Arcing : Brush motors, thermostatic contacts, wall switch and appliance plugs.
• Non-Sinusoidal Waveforms : Examples of devices creating these electrical waveforms include electronic lamp dimmers, computer switching-mode power supplies and fluorescent lamps.
• Cross Talk: This test measures trip avoidance for an AFCI when an arc is detected in an adjacent circuit. Only the circuit with the arc should cause the breaker to trip. Not another circuit.
The 2005 NEC® will require combination-type AFCI protection in the bedroom effective on January 1, 2008. The 2008 NEC® has recently been approved by the National Fire Protection Association Standards Council for publication and will be available for purchase in September of 2007. In short, the 2008 NEC 210.12 expands the AFCI protection requirement into other rooms of the house.
The NEC Code Panel has taken the next step in the requirement of AFCI by expanding protection into a number of additional rooms, using language that parallels the language found in 210.52 (A) (requirement for receptacle installation). A few other areas such as closets and hallways were also added.
(B) Dwelling Units. All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sun rooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter, combination-type, installed to provide protection of the branch circuit.