Welcome back to this series of articles discussing the various requirements for branch circuits and feeders in the National Electrical Code (NEC). Last month’s article took an in-depth look at where Article 210 requires ground-fault circuit interrupter (GFCI) protection, primarily for receptacles. This issue we will shift our focus to the arc-fault circuit interrupter (AFCI) protection required by Section 210.12. Whereas GFCI protection is focused mainly on requirements for receptacles, AFCI is more about safeguarding the entire branch circuit. 

We will start our journey by going to Section 210.12, which is broken up into different subsections that cover methods to provide AFCI protection, where it is required and what happens when a branch circuit without AFCI is added to or modified. Regardless of where the AFCI will be installed, all the devices must be listed and installed in a readily accessible location so that if they trip, they can easily be reset. We will start by jumping ahead a bit to discuss locations where AFCIs are required and then cover how the NEC allows for providing the required protection of the branch circuit.

Where do they go?

Section 210.12(B) covers locations in dwelling units that require AFCIs; the section begins stating which branch circuits are appropriate, i.e., 120V, single-phase branch circuits. This means that circuits operating at 240V will not require AFCI protection. 

There is also guidance on the ratings of branch circuits that require AFCI protection. AFCI is only required for 10A, 15A and 20A branch circuits, which means we won’t need to track down an AFCI circuit breaker for the range circuit or an electric clothes dryer. 

Section 210.12(B) requires AFCI protection to branch circuits with outlets or devices in areas in listed specific locations. Even if a branch circuit supplies receptacles or lighting outlets not in one of the listed locations, it still might need AFCI protection if a device, such as a switch, is installed in a listed location.

What’s on the list?

So, what are the specific locations that require AFCI protection? The list has been slowly expanding over several cycles but has remained roughly the same for the 2020 and 2023 NEC editions. It has pretty much expanded to cover most of a dwelling unit over time, and it might be easier to simply discuss the areas of a dwelling that do not require AFCI protection. 

The main areas of a dwelling that are not listed include bathrooms, garages or detached buildings, attics, and outdoor areas. Several folks brought up expanding the list into some of these areas for the 2026 edition, but these suggestions were voted down and the list will remain as is going forward. Fire alarm systems are also excepted where an unexpected interruption of power would leave a critical fire and life safety system unable to function. 

Remember, the requirement is for branch circuits that supply outlets or devices in one of the required locations. So just because a location isn’t listed, it doesn’t mean a branch circuit supplying a light or receptacle in that area won’t require AFCI. For example, it is not uncommon for a bathroom lighting circuit to also supply lighting in the hallway or bedroom, where AFCI is required for the branch circuit. Another example needing AFCI protection might be an outdoor lighting circuit with a switch mounted by a sliding door off the back of the kitchen. 

There are also requirements for AFCI in dormitories, hotel rooms, patient rooms in nursing homes and sleeping areas for public service groups such as fire stations. In dormitory units, the list is similar to those in dwellings, except there may be different spaces. However, those that do exist in dormitories are often used similarly to those in a dwelling. The same goes for other sleeping quarters, such as guest rooms and hotel and motel suites. 

How to provide protection

Now let’s take a look at how AFCI protection can be achieved. Probably the most common and popular method is to install a combination-type AFCI circuit breaker in the panelboard. Combination-type AFCI circuit breakers detect series and parallel arcs in the circuit and therefore don’t need anything else to help protect the circuit from arcs.
Since they are installed where the circuit gets its supply, that is all that must be installed. But there are five other ways 210.12(A) can be used to provide AFCI protection. 

One allows for the use of a branch/feeder­-type circuit breaker in the panelboard in combination with an AFCI device at the first outlet to protect everything downstream. This first outlet must be marked as such. The branch/feeder protection at the circuit breaker typically provides parallel arc-fault protection, while the outlet device provides the series arc-fault protection. These seem to be phasing out in new installations because of the convenience of the combination-type circuit breaker, but they can still be used. 

There are also two methods that can use a standard circuit breaker and an outlet­-type AFCI device at the first outlet to protect everything downstream; however, both require protection of the wiring that runs from the panelboard to the first outlet. This protection can either be achieved by having the branch circuit wiring inside a metal raceway that qualifies as an equipment grounding conductor per 250.118, or it can be achieved by using a wiring method that can be encased in at least 2 inches of concrete. This extra protection of the wiring method prevents damage that could cause an arcing fault in the wiring between the panelboard and the first outlet.

The final two methods use either a supplemental arc protection circuit breaker or a standard circuit breaker, but they come with some serious conditions. 

First, to use either of these methods, the wiring must be continuous from the panelboard to the first outlet and not exceed a certain length, depending on the conductor size. Next, the first outlet must be marked to indicate it is the first outlet on the circuit. And finally, if using the standard circuit breaker option, the circuit breaker and the outlet-type AFCI device must be listed and identified as a system combination-­type AFCI. While these methods are obtainable, the combination-type AFCI circuit breaker is far more convenient and without restrictions.

Branch circuit changes

Finally, there is the question of what happens if a branch circuit is modified or extended. Section 210.8(E) specifies that in this case, AFCI protection must be provided. This can either be achieved by any of the means discussed here today, or by placing an AFCI outlet-type device at the first receptacle outlet of the circuit. However, these only apply if the branch circuit modification or extension is longer than 6 feet. 

Now that we have discussed where AFCI and GFCI protection is required, we must discuss where outlets are required to be placed. Next month’s article will head further into Article 210 and cover outlet placement.

Until next time, stay safe and remember to always test before you touch! 

stock.adobe.com / Serhii Savchenko