2021 IRC Chapter 39
This lesson covers where a dwelling must have a receptacle outlet, not how the circuit feeding it is protected or sized. Those questions are answered elsewhere: circuit sizing was Lesson 4, and GFCI and AFCI protection is Lesson 6. Here the question is simpler and shows up on nearly every inspection: is there an outlet where the code says there has to be one, in the kitchen, the bathroom, along every wall, outdoors, in the laundry area, the basement, the garage, the hallway, and near the HVAC equipment. These placement rules exist so that an occupant is never more than a few feet from a place to plug something in, which in practice is also what keeps extension cords from becoming the default wiring method in a house.
E3901.2 sets the baseline rule for kitchens, family rooms, dining rooms, living rooms, bedrooms, dens, and similar rooms: receptacle outlets must be placed so that no point measured horizontally along the floor line of any wall space is more than 6 feet from an outlet (E3901.2.1). Applied wall by wall, that works out to receptacles spaced no more than 12 feet apart along a continuous wall, since two outlets 12 feet apart each cover 6 feet in either direction. Under E3901.2.2, a wall space is any space 2 feet or more in width, including space measured around corners, that is unbroken along the floor line by doorways and similar openings, fireplaces, and fixed cabinets without countertops; a narrow strip less than 2 feet wide does not by itself force an additional outlet. Fixed panels in exterior walls and fixed room dividers such as railings and freestanding bar-type counters count as wall space too. A floor receptacle counts toward the total only if it is within 18 inches of the wall (E3901.2.3).
Kitchen and dining area countertops get their own, tighter version of the same idea. Under E3901.4.1, a receptacle outlet must be installed at each wall countertop or work surface 12 inches or wider, so that no point along the wall line is more than 24 inches, measured horizontally, from an outlet. No receptacle is required on the wall directly behind a range, counter-mounted cooking unit, or sink in the arrangement shown in Figure E3901.4.1. Countertop receptacles must be on or no more than 20 inches above the counter, or no more than 12 inches below it where the counter does not extend more than 6 inches beyond its support base (E3901.4.3), and a receptacle may not be installed face-up in a countertop unless it is listed for that use (E4002.16). These receptacles are supplied by the small-appliance branch circuits from Lesson 4, never from the general lighting circuit, and countertop receptacles are GFCI protected, which Lesson 6 covers in detail.
Under E3901.4.2 of the 2021 IRC, islands and peninsular countertops are sized for receptacles by countertop area rather than by a fixed distance rule: at least one receptacle outlet is required for the first 9 square feet of countertop space or any fraction of it, and one more for every additional 18 square feet or fraction of it beyond that. A peninsular countertop is measured from the connected perpendicular wall, and at least one of the required receptacles must be located within 2 feet of the outer end of the peninsula; beyond that, additional locations are left to the installer, designer, or owner, within the location limits of E3901.4.3. Local amendments can change any of this, so confirm against the edition and amendments a jurisdiction has actually adopted.
E3901.6 requires at least one receptacle outlet in each bathroom, located within 3 feet (36 inches) of the outside edge of each lavatory basin. That receptacle may be placed on the wall or partition adjacent to the basin or countertop, on the countertop itself, or on the side or face of the basin cabinet, but not more than 12 inches below the top of the basin or countertop, which rules out mounting it low enough to invite a dangling cord next to the sink. Every bathroom receptacle is GFCI protected regardless of its distance from water, which Lesson 6 covers.
Under E3901.7, each dwelling unit with direct access to grade needs at least one receptacle outlet at the front and one at the back, each readily accessible from grade and not more than 6 feet 6 inches above grade. Balconies, decks, and porches that are accessible from inside the dwelling (within 4 inches horizontally of the dwelling unit) also need at least one receptacle outlet accessible from the balcony, deck, or porch, located not more than 6 feet 6 inches above its surface. A receptacle that can be reached only from an elevated deck is not readily accessible from grade, so it does not stand in for the grade-level outlet.
E3901.8 requires at least one receptacle outlet in areas designated for laundry equipment, and E3901.5 requires an appliance receptacle such as the laundry one to be within 6 feet of the intended location of the appliance. That outlet is on its own 20-ampere circuit that serves only receptacle outlets in the laundry area (E3703.3, Lesson 4). Separately, E3901.9 requires at least one receptacle outlet, in addition to any provided for specific equipment, in each separate unfinished portion of a basement, in each vehicle bay of an attached garage or of a detached garage with electric power, and in accessory buildings with electric power; garage receptacles are not more than 5.5 feet above the floor. A finished basement room is not an unfinished portion, so it follows the general wall-space rule of E3901.2 like any other living space.
A hallway 10 feet or more in length, measured along the centerline without passing through a doorway, must have at least one receptacle outlet (E3901.10). A foyer that is not part of a hallway and is larger than 60 square feet needs a receptacle in each wall space 3 feet or more wide (E3901.11). Separately, E3901.12 also requires a 125-volt, 15- or 20-ampere receptacle outlet at an accessible location on the same level and within 25 feet of heating, air-conditioning, and refrigeration equipment such as a furnace, air handler, or condensing unit, to give a technician a place to plug in test equipment or a work light without running an extension cord from another room. That servicing receptacle is not permitted to be connected to the load side of the equipment's own disconnecting means, since the point is to have power available even when the equipment itself is shut off for service.
A worked example: a kitchen island countertop measures 4 feet by 6 feet, or 24 square feet. The first 9 square feet requires 1 receptacle. The remaining 15 square feet is less than 18 square feet, but any fraction of the 18-square-foot increment still counts, so a second receptacle is required. A 4-foot by 8-foot peninsula, 32 square feet, needs the same math: 1 for the first 9 square feet, 1 more for the next 18 square feet, and 1 more for the last 5 square feet, since any fraction of an increment counts, for 3 receptacles total, with at least one of them within 2 feet of the peninsula's outer end.
In the field
A common GCHS rehab scenario is a kitchen remodel that adds a peninsula where a wall used to be. Staff estimating the electrical scope should count countertop square footage the way the code does, not assume "one outlet per island" the way older jobs were often wired, and should flag any bathroom vanity outlet mounted directly under the sink drain, which almost always violates the 12-inch-below- countertop limit and invites a slow drip straight onto a receptacle.
1. Under the general wall-space rule, a receptacle outlet must be placed so that no point along a qualifying wall is more than:
2. A short section of wall next to a door is only 18 inches wide. Under the wall-space rule, this space:
3. Along a kitchen countertop, a receptacle outlet must be placed so that no point along the countertop wall line is more than:
4. An island countertop measures 24 square feet. Under the area-based method of E3901.4.2, how many receptacle outlets are required at minimum?
5. On a peninsula, at least one of the required receptacles must be located:
6. A bathroom receptacle outlet must be located within what distance of the outside edge of the basin?
7. An inspector finds a bathroom receptacle mounted on the cabinet face, 18 inches below the countertop. This is:
8. One- and two-family dwellings must have at least one outdoor receptacle at the front and one at the rear, each no higher above grade than:
9. A rear deck is reached through a door from inside the dwelling. Besides the required grade-level receptacle at the rear of the house, the deck itself needs:
10. A hallway in a dwelling unit triggers the receptacle requirement once its length, measured along the centerline, reaches:
11. A receptacle outlet for servicing HVAC equipment must be located:
12. An inspector finds a finished basement family room with only the general wall-space receptacles present and no receptacle installed specifically for the basement. Is this compliant?
13. A garage on the property is detached from the house and has electric power run to it for lighting. Under E3901.9, this garage:
14. Which circuit supplies the required laundry area receptacle outlet?