Branch Circuits - Part Two

Article 210 provides GFCI requirements in 210.8 and AFCI requirements in 210.12. These requirements apply to 125V receptacles rated at 15A or 20A (circuits are 120V, but the receptacles are rated 125V). Any time we refer to a receptacle in this discussion of GFCIs or AFCIs, we are referring to this kind of receptacle only.

Article 210 frequently uses the word “outlet.” However, it's important to note this isn't limited to just receptacles. Article 100 defines an outlet as a point in the wiring system where current supplies a load. Although this definition includes receptacles, it also applies to outlets for lighting, paddle fans, and smoke alarms.

GFCI basics. Before we get into GFCI requirements, let's address two basic points. First, GFCIs do work on 2-wire circuits. A GFCI works by measuring the current on the ungrounded conductor and comparing it to the current on the grounded (neutral) conductor. If the difference between the two is greater than 4 to 6 milliamperes, the circuit is interrupted. With this in mind, you can see how the equipment grounding conductor does not play a pivotal role in the operation of the GFCI.

It's also worth noting that all Code-change proposals to lessen the protection in bathrooms have been rejected. In fact, GFCI coverage has been expanding (see “GFCI Expanded Coverage” on page 59), and will probably continue to do so in the future. The reason is simple: safety.

GFCIs in dwelling units. GFCI protection is required for receptacles installed in any of the following eight areas of a dwelling unit [210.8(A)]:

Bathroom
Garage
Outside
Crawl space (at or below grade)
Unfinished basement
Kitchen
Laundry
Boathouse

Bathroom. A bathroom must have at least one 15A or 20A, 125V receptacle. All bathroom receptacles must be GFCI-protected. At least one receptacle must be within 3 feet of the outside edge of each basin [210.52(D)].

This circuit can have no other outlets [210.11(C)(3)]. This means, for example, it can't supply power to an outside receptacle or a garage receptacle. Exception: Where the 20A circuit supplies only a single bathroom, it can supply power to outlets for other equipment within the same bathroom, such as lighting outlets or an exhaust fan. In that case, follow the requirements of 210.23(A)(1) and (A)(2) for circuit loading.

Garage. A garage attached to a dwelling unit must have a receptacle [210.52(G)]. In an accessory building or a detached garage with power, a receptacle is also required. In either case, the receptacle must be GFCI protected [210.8(A)(2)]. A couple of exceptions exist:

Receptacles that aren't readily accessible, such as those in the ceiling for the garage door opener motor. See the definition of “Readily Accessible” in Art. 100.
A single receptacle on a dedicated branch circuit identified for a specific cord-and-plug connected appliance, such as a refrigerator or freezer. You can use a duplex receptacle without GFCI protection for two such appliances. Receptacles permitted by this exception must be within 6 feet of the appliance [210.50(C)].

Receptacles that aren't readily accessible (or those for a dedicated branch circuit for a specific cord-and-plug connected appliance, as permitted in the two exceptions above) do not count as the required receptacle described in 210.52(G).

Outside. Each ground floor unit of a multifamily dwelling (one that contains three or more dwelling units [Art. 100]) with individual exterior entrances must have at least one outdoor receptacle with GFCI protection. Dwelling units above ground level of a multifamily dwelling unit do not require an outdoor receptacle. If you choose to install one, it still must be GFCI protected [210.52(E)].

Receptacles installed on the outside of a dwelling unit (even if installed under the eaves of roofs) must be GFCI protected.

GFCI protection isn't required for a fixed electric snow-melting or deicing equipment receptacle supplied by a dedicated branch circuit, if the receptacle isn't readily accessible, and it complies with the requirements of 426.28 for ground-fault protection of equipment.

Crawl space. Receptacles installed in crawl spaces at or below grade of a dwelling unit must be GFCI protected. You don't have to install a receptacle in the crawl space, except when heating, air-conditioning, and refrigeration equipment is installed there [210.63].

Basement. You must install a receptacle in each unfinished portion of a dwelling unit basement [210.52(G)]. If this space isn't intended as a habitable room (and is limited to storage and work areas), provide GFCI protection for all receptacles (Fig. 1). Two exceptions exist:

Receptacles that aren't readily accessible.
A receptacle on a dedicated branch circuit identified for a specific cord-and-plug connected appliance.

Kitchen. GFCI protection is required for all receptacles that serve countertop surfaces in a dwelling unit. It's not required for receptacles that serve built-in appliances that do not serve the countertop, such as dishwashers and kitchen waste disposals. See 210.52(C) for location requirements.

Laundry and wet bars. GFCI protection is required for receptacles located within 6 feet of a laundry, utility room, or wet bar sink [210.8(A)(7), 210.52(F)]. There are no exceptions to this rule, so even a receptacle for a clothes washer must be GFCI protected if it is within 6 feet of the sink (Fig. 2).

Boathouse. You don't have to install a receptacle in a boathouse. But if you do, it must be GFCI protected.

Commercial/industrial GFCI. Remember, we're referring only to 125V receptacles rated at 15A or 20A [210.8(B)]. The requirements don't apply to equipment rated 230V, such as a baseboard heater or room air conditioner — nor do they apply to welding receptacles or other outlets that aren't 125V (either 15A or 20A). GFCI protection is required for all receptacles installed in the following commercial/industrial locations.

Bathroom. You don't have to install a receptacle in a commercial or industrial bathroom (as defined in Art. 100). But if you do, it must be GFCI protected.

Kitchen. All receptacles installed in a kitchen must be GFCI protected, even those that do not serve the countertop. GFCI protection isn't required for receptacles in employee break rooms containing portable cooking appliances. For this requirement, a “kitchen” is an area with a sink and permanent facilities for food preparation and cooking.

Rooftop. Receptacles installed on rooftops must be GFCI protected. A receptacle must be installed within 25 feet of heating, air-conditioning, and refrigeration equipment [210.63].

Just like the rule for outdoor dwelling unit receptacles, there is an exception for installations that fall under 426.28.

Outdoor public space. Receptacles installed outdoors in public spaces used by (or accessible to) the public must be GFCI protected. Whether the public has access is a judgment call, so check with the AHJ.

Heating, air-conditioning, and refrigeration equipment

All outdoor receptacles installed at an accessible location for the servicing of heating, air-conditioning, and refrigeration equipment per 210.63 must be GFCI protected.

Arc-fault circuit-interrupters (AFCIs). An AFCI device de-energizes the circuit when it detects the current waveform characteristics that are unique to an arcing fault [210.12(A) (Fig. 3). It does not protect a person from shock. That's what a GFCI does. AFCIs prevent fires from arc faults.

You cannot use an AFCI device to satisfy GFCI requirements (or vice versa). GFCI and AFCI devices are based on entirely different principles, though you can get both functions in one combination AFCI/GFCI device.

After January 1, 2008 (basically a 2008 NEC requirement), AFCI protection must be provided by a combination AFCI device (see “Why Combination Devices?” on page 54), as opposed to the branch/feeder type in use today.

Bedroom circuits. A 120V branch circuit that supplies outlets in dwelling unit bedrooms must be protected by a listed AFCI device (Fig. 4).

Smoke alarms. These have to be AFCI protected if on a 15A or 20A bedroom circuit in a dwelling unit. This may seem to conflict with Art. 760, but it doesn't. The exemption from AFCI protection for the fire alarm circuit [760.21 and 760.41] doesn't apply to the smoke alarm circuit. Why? Because a smoke alarm circuit isn't a fire alarm circuit. It's an alarm circuit [See NFPA 72, National Fire Alarm Code].

The GFCI requirements apply to receptacle outlets. The AFCI requirements apply to all outlets — where electricity is being “let out” so people can use it, if those outlets are 125V and either 15A or 20A.

GFCIs apply to dwellings and to commercial and industrial applications. They keep people from being shocked. For the time being, AFCIs apply only to dwelling units. They keep wires from causing a fire where people are sleeping in their homes. Knowing you've properly applied GFCI and AFCI requirements to your branch circuits should help you sleep easier.

Sidebar: Why Combination Devices?

Standard branch/feeder AFCI devices operate when the arc exceeds 75A peak, but combination AFCI protection devices detect arcs as low as 5A peak. This dramatic difference in detection enhances safety performance. Combination devices are also intended to protect the premises wiring as well as the cord connecting the appliance. These devices also “see” arc faults for both series arcs and parallel arcs, whereas branch/feeder type AFCIs only respond to parallel arcs. See UL 1699, “Standard for Arc-Fault Circuit Interrupters” (www.UL.com) for information on the differences between the two types of devices.