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I am installing 120v wiring for a dorm-type setting, and some of the rooms are over 70 feet from the breaker panel. The NEC says that the home run may not exceed 50 feet for 14 AWG and 70 feet for 12 AWG conductors. If it does the first receptacle in the branch circuit has to be an AFCI receptacle.

So, in the case where the 1st receptacle is more than 70 feet from the panel do I need both (an AFCI breaker and an ACFI Receptacle)?

  • What make and model of breaker are you installing? – ThreePhaseEel Oct 11 '16 at 23:34
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I could be wrong here, but the way the code is written, the circuit length should only matter if...

  • The AFCI protection is provided by a receptacle type device installed at the first outlet.
  • A supplemental arc protection circuit breaker is installed at the origin of the circuit, and a receptacle type AFCI device is installed at the first outlet.

210.12(A)(1) allows the circuit to be protected by a "combination-type arc-fault circuit interrupter", without any mention of the length of the circuit. So I would expect as long as you're installing a combination-type AFCI, and not a "supplemental arc protection circuit breaker". Then there should be no problem. But I've been known to misinterpret code from time to time.

National Electrical Code 2017

Chapter 2 Wiring and Protection

Article 210 Branch Circuits

210.12 Arc-fault Circuit-Interrupter Protection.

(A) Dwelling Units. All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas shall be protected by any of the means described in 210.12(A)(1) through (6):

(1) A listed combination-type arc-fault circuit interrupter, installed to provide protection of the entire branch circuit.

...

(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:

...

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 14 AWG conductors or 21.3 m (70 ft) for 12 AWG conductors.

...

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  • The outlet cannot be longer than 50' from the panel for 14 awg and 70' for 12 awg 210.12.A.3.B. Over these lengths an afci outlet is required is the way I read it. – Ed Beal Oct 12 '16 at 14:37
  • @EdBeal The code says "shall be protected by any of the means described in 210.12(A)(1) through (6)". To me, that means if you installed a combination AFCI breaker (the first method), you're done. Instead, if you chose to install a supplemental arc protection circuit breaker and AFCI at the first outlet (third method), then you're limited to 50' or 70'. The code does not say "shall be protected as described by", or "shall be protected by bits and pieces of the methods listed below". – Tester101 Oct 12 '16 at 16:21
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    Notice in the edit of the answer, the 50/70 ft condition only applies to means 3. – Tester101 Oct 12 '16 at 16:28

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