Branch circuits
A branch circuit is the wiring between the final overcurrent device and the outlets it serves. NEC Article 210 sets which branch circuits a building needs, where GFCI and AFCI protection is required, where receptacle outlets go, and how circuits are rated. Exam questions on it are mostly short location and distance lookups.
What Article 210 covers and why it matters on the exam
Article 210 governs the last leg of the wiring system, so it touches almost every room you wire. Exam questions are usually quick lookups: is GFCI required here, how far apart can these receptacles be, how many 20 A circuits does this kitchen need. Know where to find GFCI (210.8), required circuits (210.11), AFCI (210.12), ratings and loads (210.19 to 210.23) and receptacle outlets (210.52).
GFCI protection: 210.8 and the 2023 changes
GFCI protection is required for receptacles where a person is likely to be wet or grounded. For dwellings, 210.8(A) covers 125-volt through 250-volt receptacles on single-phase circuits of 150 volts or less to ground, so a 240-volt dryer receptacle in a listed location needs GFCI too.
The dwelling list includes bathrooms, garages and accessory buildings, outdoors, crawl spaces, basements, kitchens, laundry areas, boathouses, and receptacles within 6 ft of a sink bowl, bathtub or shower stall. Distances are measured along the shortest cord path, not through a wall, door or window.
Changes in the 2023 NEC that show up on exams:
- All kitchen receptacles. The limit to receptacles serving the countertop was dropped, so a dwelling refrigerator receptacle now needs GFCI.
- Indoor damp and wet locations were added to the dwelling list.
- Specific appliances. 210.8(D) points to the appliance list in 422.5(A), which includes dishwashers.
- Outdoor outlets. 210.8(F) covers dwelling outdoor outlets, not just receptacles, rated 50 A or less on single-phase circuits of 150 volts or less to ground, such as an air-conditioning condenser.
For other than dwellings, 210.8(B) covers places such as bathrooms, kitchens, rooftops, outdoors, locker rooms with showers and service bays. It reaches single-phase receptacles up to 50 A and three-phase receptacles up to 100 A, at 150 volts or less to ground.
AFCI protection: 210.12
AFCI protection is required for 120-volt, single-phase, 10-, 15- and 20-ampere branch circuits that supply outlets or devices in most dwelling living spaces, per 210.12(B). The list includes kitchens, family rooms, dining rooms, living rooms, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas and similar rooms.
Bathrooms, garages and outdoors are not on the AFCI list. Kitchens and laundry areas are on both lists, so they need GFCI and AFCI, often from a dual-function breaker. Article 210 also requires AFCI in dormitory units and hotel guest rooms. A combination-type AFCI breaker is the usual method. Extending an existing circuit 6 ft or less with no added outlets does not trigger AFCI.
Required branch circuits: 210.11
Every dwelling needs these 20 A circuits on top of the general lighting circuits, under 210.11(C):
- At least two 20 A small-appliance circuits for the kitchen, pantry, breakfast room and dining room receptacles
- At least one 20 A laundry circuit, which may serve laundry receptacles only
- At least one 120-volt, 20 A bathroom circuit, either for bathroom receptacles only or for all outlets in a single bathroom
- At least one 120-volt, 20 A circuit for attached garages and for detached garages with power
Small-appliance circuits may not supply outdoor receptacles or the range hood. See how these circuits count toward service size in dwelling load calculations.
Receptacle outlets: 210.52
210.52 sets where dwelling receptacles must go, and the exam tests the distances.
- General wall space (210.52(A)). No point along the floor line may be more than 6 ft from a receptacle, so they can be 12 ft apart. Any wall 2 ft or wider counts.
- Kitchen countertops (210.52(C)). No point along the wall line may be more than 24 in from a receptacle, so spacing is 4 ft maximum. Any counter space 12 in or wider needs one. Under 2023, an island or peninsula without a receptacle needs provisions for adding one later.
- Bathrooms (210.52(D)). At least one receptacle within 3 ft of the outside edge of each basin.
- Outdoors (210.52(E)). One-family dwellings need one at the front and one at the back, no more than 6 ft 6 in above grade.
- Garages and hallways. At least one receptacle in each garage vehicle bay, and one in any hallway 10 ft or longer.
Branch circuit ratings and loads
A branch circuit is rated by its overcurrent device, not its wire size. Multioutlet circuits are rated 15, 20, 30, 40 or 50 A, and the 2023 NEC added a 10 A rating that may not supply receptacles. Under 210.19, conductors must carry 125% of the continuous load (three hours or more) plus the noncontinuous load. Under 210.21 and 210.23:
- 15 A receptacles are allowed on a 20 A circuit with two or more receptacles.
- A single receptacle on an individual circuit must be rated at least the circuit rating.
- On a 15 or 20 A circuit, one cord-and-plug load may use 80% of the rating, and fastened-in-place equipment 50% when other loads are also served.
Worked examples
Example 1: countertop receptacles. A 13 ft (156 in) wall countertop has no breaks. The end receptacles go 24 in from each end, at 24 and 132 in, leaving 108 in between. Spacing may not exceed 48 in: 108 ÷ 48 = 2.25, so 3 spaces, which is 4 receptacles (at 24, 60, 96 and 132 in).
Example 2: living room wall. An unbroken 26 ft wall needs receptacles within 6 ft of each end and no more than 12 ft apart. (26 − 12) ÷ 12 = 1.17, rounded up to 2 spaces, so 3 receptacles (at 6, 13 and 20 ft).
Example 3: continuous lighting load. A 120-volt circuit supplies 1,800 VA of continuous lighting. I = 1,800 ÷ 120 = 15 A, and 15 × 1.25 = 18.75 A minimum, so a 20 A circuit works. Table 310.16 gives 20 A for 12 AWG copper at 60°C. More on the 125% rule in overcurrent protection and conductor ampacity.
Common exam mistakes
- Using the 2020 kitchen rule. Under 2023, every dwelling kitchen receptacle needs GFCI, not just countertop receptacles.
- Forgetting that 210.8(A) reaches 250-volt receptacles, such as dryer receptacles in laundry areas.
- Putting bathrooms or garages on the AFCI list. They are GFCI locations, not AFCI locations.
- Mixing up the 6 ft wall rule with the 24 in countertop rule.
Practice questions
More mixed questions: the free practice test and exam calculations guide.
Frequently asked questions
Does a refrigerator receptacle need GFCI protection under the 2023 NEC?
Yes, in a dwelling kitchen. The 2023 edition applies 210.8(A) to all kitchen receptacles, not only those serving the countertop.
Which rooms need both GFCI and AFCI protection?
In a dwelling, kitchens and laundry areas are on both the 210.8(A) GFCI list and the 210.12(B) AFCI list, so their 120-volt, 15- and 20-ampere receptacles need both.
How many receptacles can go on a 20 amp circuit in a house?
The NEC sets no maximum for dwelling general-purpose circuits. Some local codes add a limit, so check your jurisdiction.
How far apart can receptacles be on a wall?
Up to 12 ft apart along a general dwelling wall, since no point may be more than 6 ft from a receptacle (210.52(A)). Along a kitchen countertop, 4 ft apart, since no point may be more than 24 in from one.
Do bathroom receptacles need AFCI protection?
No. Bathrooms are not on the 210.12(B) AFCI list, but bathroom receptacles need GFCI under 210.8(A).