Installation requirements for arc-fault circuit interrupters (AFCI) in 210.12 of National Electrical Code (NEC) have been modified considerably in the past three NEC cycles and have changed dramatically in the 2014 NEC. To understand the ramifications of these changes, the best method is to provide the actual text from the 2014 NEC and then follow this text with an explanation.
The introductory text in 210.12 has been modified as follows: “Arc-fault circuit-interrupter protection shall be provided as required in 210.12(A), (B), and (C). The arc-fault circuit interrupter shall be installed in a readily accessible location.” There are three subsections to the section with (A) covering AFCI protection requirements for typical dwelling units, (B) covering AFCI protection for branch-circuit extensions and modifications for dwelling units, and (C) covering AFCI protection for dormitory units. A new last sentence in the introductory text requires AFCIs to be installed in a readily accessible location, so these devices can be tested and reset. Dormitory units were added to the AFCI requirement since many of the same safety issues occur in dormitories as in other dwelling areas.
In 210.12(A), kitchens and laundry areas have been added to the rooms or areas requiring AFCI protection. In addition, the installer is provided with six different methods that can be used to provide this protection. The first protection method is “(1) A listed combination-type arc-fault circuit interrupter, installed to provide protection of the entire branch circuit.” This method of protection has existed since the 2008 NEC and requires a listed combination AFCI device.
The second method is “(2) A listed branch/feeder-type AFCI installed at the origin of the branch-circuit in combination with a listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet box on the branch circuit. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.” This method permits a listed branch/feeder AFCI device to be used at the source or origin of the circuit (previously permitted in the 2005 NEC and in previous editions of the Code) but only where a listed outlet branch-circuit type AFCI is installed at the first outlet box in the circuit, and it must be marked to indicate that it is the first outlet of the circuit. This permits an AFCI branch/feeder device to protect the branch circuit for parallel faults up to the AFCI outlet with the outlet providing parallel fault protection for the remainder of the circuit and series-fault protection for the entire circuit.
The next AFCI protection method is “(3) A listed supplemental arc protection circuit breaker installed at the origin of the branch circuit in combination with a listed outlet branch-circuit type arc-fault circuit interrupter installed at the first outlet box on the branch circuit where all of the following conditions are met: a. The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit arc-fault circuit interrupter. b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 ft) for a 14 AWG conductor or 21.3 m (70 ft) for a 12 AWG conductor. c. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.” While this method is somewhat longer than the first two, let’s take it a piece at a time and analyze it. This method introduces a supplemental arc-protection circuit breaker, installed at the origin of the circuit, to be used in combination with an outlet branch-circuit AFCI that is to be located at the first outlet, often in a multiple outlet circuit, although this circuit could supply an individual branch circuit. Remember that an individual branch circuit is defined as a branch circuit that supplies only one utilization equipment or outlet. The length of the circuit from the source connection in the panelboard plus the minimum size of conductors in this part of the circuit is critical for the operation of the circuit. To make it easy to inspect and troubleshoot, the first outlet—where the listed outlet branch-circuit AFCI device is located—must be marked. This marking could be similar to the marking provided with ground-fault circuit interrupter devices or could be etched into the cover plate. The NEC has not clearly defined the method for marking the outlet.
There are three more methods of protection, an exception, and three informational notes—more than I can cover in this space—so, I’ll discuss the new text accepted for the 2014 NEC further next month.