Changes have been made to this section to address fire alarm circuiting, Type MC Cables, concrete-encased raceways, and branch circuit extensions or modifications.

210.12(A) Where Required. All 15A or 20A, 120V branch circuits in dwelling units supplying outlets in family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas must be protected by a listed AFCI device of the combination type. (click here to see Fig. 3)

Ex. 1: AFCI protection can be of the branch circuit type located at the first outlet if the circuit conductors are installed in RMC, IMC, EMT, or Type MC or steel armored Type AC cable meeting the requirements of 250.118, and the AFCI device is contained in a metal outlet or junction box.

Ex. 2: Where a listed metal or nonmetallic conduit or tubing is encased in not less than 2 in. of concrete for the portion of the branch circuit between the branch circuit overcurrent device and the first outlet, an outlet branch circuit AFCI at the first outlet is permitted to provide protection for the remaining portion of the branch circuit.

Ex. 3: AFCI protection can be omitted for an individual branch circuit to a fire alarm system in accordance with 760.41(B) and 760.121(B), if the circuit conductors are installed in RMC, IMC, EMT, or steel sheath Type AC or MC cable that qualifies as an equipment grounding conductor in accordance with 250.118, with metal outlet and junction boxes.

(B) Branch-Circuit Extensions or Modifications — Dwelling Units. Where branch-circuit wiring is modified, replaced, or extended in any of the areas specified in 210.12(A), the branch circuit must be protected by:

(1) A listed combination AFCI located at the origin of the branch circuit; or

(2) A listed outlet branch circuit AFCI located at the first receptacle outlet of the existing branch circuit.

Analysis: Fire alarm systems covered by Art. 760 have been exempted from the requirements of AFCI protection, but the circuiting of those systems was previously not addressed. This inadvertently left a loophole for installers to incorporate other outlets in areas specified by 210.12 on the same circuit as the fire alarm system and omit the AFCI protection required for circuits in those areas. This change also includes MC cable as a permitted wiring method when employing this exception.

Section 210.12 Ex. 1 has been revised to allow MC cables as one of the allowable wiring methods in the exception. MC cable meeting the requirements of 250.118 has been proven safe, so this allowance seems fair enough.

New to the NEC is 210.12(A) Ex. 2. Concrete encased raceways obviously provide an increased level of protection for circuit conductors, so a new exception was added to allow such raceways to be installed without AFCI protection at the source, provided that there’s an outlet type AFCI installed at the first outlet of the circuit.

Also new to the NEC is subsection (B), dealing with branch-circuit extensions or modifications in existing buildings. The question of what to do with existing buildings in regard to AFCI protection has been prevalent ever since AFCI requirements were added to the Code in 1999. With this change, it’s clear that when branch circuit wiring is extended or modified, some level of AFCI protection will be required.