Understand the National Electrical Code

Arc Fault Protection for Dwelling Units

The 2011 NEC 70 Code Book has once again managed to confuse electricians nationwide, simply because sometimes we fail to think about basic definitions. In this post I hope to correct any confusion, specifically concerning Arc Fault protection in dwelling units.

In order to understand what I am referring to, let’s take a look at what the 2011 NEC says…


210.12 Arc-Fault Circuit-Interrupter Protection.

(A) 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, sunrooms, 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.

At first glance, you might be saying to yourself,”seems pretty clear to me”. Let me ask you this, does the above code mean that only  receptacles in the stated rooms are required to be protected via arc fault? If you answered “no, it means receptacles and lighting outlets”, then CONGRATULATIONS!! You are absolutely correct. If, on the other hand, you answered “yes”, you should continue to read further.

The misunderstanding of the 2011 Arc Fault Code is whether or not it refers to receptacles and/or lighting. In order to clear this up, we simply look at the much overlooked section in the code – Definitions.

The definition of “outlet” in the 2011 NEC is as follows:

Outlet. A point on the wiring system at which current is taken to supply utilization equipment.

Now we need to understand “utilization equipment”:

Utilization Equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.

To state it simply – an outlet is a point (box) which essentially make something happen – lights on, plug in tv, etc.

With these basic definitions, you can see that the 2011 NEC Arc fault section for dwelling units refers to both receptacle and lighting outlets.

I hope this helps. It is often easy to get tied up in the Code. As electricians we have much to take in to account everyday. Article 100 is a great starting point if you are having trouble with some of the language – USE IT.