NEC Article 210: What Is a Branch Circuit & How Is It Rated?

Every receptacle, light fixture, and hardwired appliance in a building is served by a branch circuit. Understanding what a branch circuit is — where it starts, where it ends, and what determines its rating — is foundational knowledge for anyone working with the NEC. It also shows up on nearly every journeyman and master electrician exam.

This guide covers the NEC Article 100 definition of a branch circuit, all four branch circuit types, how the ampere rating is determined, what loads each circuit type is permitted to supply, conductor and OCPD sizing rules, and the 2023 NEC changes to branch circuit ratings.

Here is what we cover:

• The NEC definition of a branch circuit — exactly where it starts and ends
• All four branch circuit types defined in NEC Article 100
• How branch circuit ratings are determined — and why it is the OCPD, not the wire
• Permitted ratings: 10, 15, 20, 30, 40, and 50 amperes
• Permissible loads by circuit rating — the 80% and 50% rules
• Conductor sizing and overcurrent protection requirements
• The 2023 NEC change that added 10-ampere branch circuits

What Is a Branch Circuit? — The NEC Definition

NEC Article 100 defines a branch circuit as: “The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).”

Breaking that down:

• “Final overcurrent device” — this is the last breaker or fuse before the conductors reach the load. In a typical residential or commercial installation, that is the circuit breaker in the panel. In a system with sub-panels or tap conductors, it is the last OCPD before the circuit conductors run to the outlets.
• “The outlet(s)” — any point on the wiring system where current is taken to supply utilization equipment. This includes receptacle outlets, lighting outlets, and equipment outlets. The outlet is not just a receptacle — it is any point of load connection.

The branch circuit begins at the final OCPD and ends at the outlet. The conductors in between — the hot(s), neutral, and equipment grounding conductor — are the branch circuit conductors. The feeder conductors that supply the panel are not part of the branch circuit.

Table 1: Branch Circuit Boundaries — NEC Article 100 (2023 Edition)

System Element	Part of the Branch Circuit?	NEC Reference
Service entrance conductors	No — these are service conductors (NEC Article 230)	Article 230
Feeder conductors (panel to sub-panel)	No — these are feeder conductors (NEC Article 215)	Article 215
Final overcurrent device (circuit breaker or fuse)	No — this defines the start of the branch circuit but is not part of it	Article 100 definition
Conductors from final OCPD to outlet(s)	Yes — these are the branch circuit conductors	Article 100, Article 210
Receptacle, luminaire, or hardwired equipment terminal	Yes — this is the outlet, the termination of the branch circuit	Article 100 (“outlet” definition)

The Four Types of Branch Circuits

NEC Article 100 defines four distinct branch circuit types. Each has its own definition and, under NEC Article 210, specific rules about what loads it may supply.

1. General-Purpose Branch Circuit

Defined in NEC Article 100 as: “A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.”

This is the most common branch circuit type in residential and commercial work. A general-purpose branch circuit can supply any combination of lighting outlets, receptacle outlets, and utilization equipment. The bedroom circuits, living room circuits, and hallway lighting circuits in a dwelling are general-purpose branch circuits. In a commercial building, the lighting and receptacle circuits throughout offices and corridors are general-purpose circuits.

Typical ratings: 15A and 20A. A 15A general-purpose branch circuit is the most common circuit in residential bedrooms and living areas. A 20A general-purpose circuit is required in kitchens and bathrooms (for small appliance and bathroom branch circuits) and is common in commercial spaces.

2. Appliance Branch Circuit

Defined in NEC Article 100 as: “A branch circuit that supplies energy to one or more outlets to which appliances are to be connected and that has no permanently connected lighting fixtures not a part of an appliance.”

The key distinction from a general-purpose circuit: an appliance branch circuit does not supply permanently connected lighting fixtures that are not part of an appliance. A washing machine circuit, a dishwasher circuit, or the small appliance branch circuits required in a kitchen countertop area (NEC 210.11(C)(1)) are appliance branch circuits. These circuits may have receptacle outlets — appliances are plugged in, not hardwired.

NEC 210.11(C)(1) requires a minimum of two 20A small appliance branch circuits for the kitchen, dining room, and pantry in a dwelling unit. These are appliance branch circuits.

3. Individual Branch Circuit

Defined in NEC Article 100 as: “A branch circuit that supplies only one piece of utilization equipment.”

An individual branch circuit supplies a single load — a water heater, a central air conditioner, an electric range, a dedicated receptacle outlet for one piece of equipment, or any other single load. Most electricians call this a dedicated circuit. The load consumes the full capacity of the circuit, so no other outlets or equipment may be connected.

Individual branch circuits can be any rating appropriate for the load — they are not limited to 15, 20, 30, 40, or 50 amperes the way multiple-outlet branch circuits are. A 60A individual branch circuit for a large HVAC unit, or a 100A individual branch circuit for a large piece of commercial equipment, is permitted.

4. Multiwire Branch Circuit

Defined in NEC Article 100 as: “A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.”

The multiwire branch circuit shares a single neutral conductor between two or more hot conductors connected to different phases. The rules governing multiwire branch circuits — including the simultaneous disconnect requirement, neutral continuity requirements, and load restrictions — are covered in detail in our guide to Multi-Wire Branch Circuits: NEC Code Rules & Safety Requirements.

How Is a Branch Circuit Rated?

This is a point that trips up many apprentices — and occasionally shows up incorrectly in the field. The branch circuit rating is determined by the maximum permitted ampere rating or setting of the overcurrent device — not by the size of the conductors in the circuit.

This is stated explicitly in NEC 210.18: “Branch circuits recognized by this article shall be rated in accordance with the maximum permitted ampere rating or setting of the overcurrent device.”

If you install 10 AWG conductors on a 20A breaker, it is a 20A branch circuit — not a 30A circuit, even though 10 AWG copper can handle 30A under NEC Table 310.16. The breaker rating establishes the circuit rating. Upsizing conductors for voltage drop or any other reason does not change the rating of the branch circuit.

Permitted Branch Circuit Ratings (NEC 210.18)

For other than individual branch circuits (i.e., multiple-outlet branch circuits), the permitted ratings are fixed at:

Table 2: Permitted Branch Circuit Ratings — NEC 210.18 (2023 Edition)

Circuit Rating	Minimum Conductor Size (Copper)	Permitted for Receptacles?	Notes
10 amperes	16 AWG (where permitted)	No — receptacles not permitted	New in 2023 NEC — for specific non-receptacle loads only
15 amperes	14 AWG copper	Yes — 15A or 20A receptacles	Most common residential branch circuit
20 amperes	12 AWG copper	Yes — 20A receptacles (15A also permitted)	Required for kitchens, bathrooms, laundry in dwellings
30 amperes	10 AWG copper	Yes — only 30A receptacles	Fixed loads or luminaires in other than dwelling units; single receptacles on individual branch circuits
40 amperes	8 AWG copper	Yes — only 40A or 50A receptacles	Cooking equipment, fixed heating
50 amperes	6 AWG copper	Yes — only 50A receptacles	Cooking equipment, fixed heating

Individual branch circuits are not constrained to these five ratings — they can be any rating that matches the load and the OCPD protecting the conductors.

The 2023 NEC Change — 10-Ampere Branch Circuits

The 2023 NEC added 10-ampere branch circuits to the permitted ratings in NEC 210.18 for other-than-individual branch circuits. This change was driven by the growth of energy-efficient loads (LED lighting systems, low-power control circuits, and similar applications) that operate well within 10A at all times.

Critical restriction: A 10-ampere branch circuit is not permitted to supply receptacle outlets. This is specifically stated because receptacles introduce unpredictable plug-in loads that could easily exceed 10A. The 10A rating is intended for fixed, non-receptacle loads where the current demand is known and controlled.

Permissible Loads by Branch Circuit Rating

NEC 210.23 establishes what loads a multiple-outlet branch circuit is permitted to supply. The key rules are not just about total current — they also limit individual equipment loads to prevent one device from dominating a shared circuit.

15 and 20-Ampere Branch Circuits — NEC 210.23(B)

A 15A or 20A branch circuit may supply lighting outlets, lighting units, or any other utilization equipment, subject to two load limits:

Rule 1 — Cord-and-plug connected equipment not fastened in place (NEC 210.23(B)(1)): The rating of any single cord-and-plug connected piece of equipment that is not fastened in place must not exceed 80% of the branch-circuit ampere rating.

• On a 20A circuit: maximum 16A for any single portable device
• On a 15A circuit: maximum 12A for any single portable device

Rule 2 — Utilization equipment fastened in place (NEC 210.23(B)(2)): Where a circuit supplies both utilization equipment that is fastened in place and also has lighting outlets, luminaires, or receptacles for non-fastened equipment, the fastened-in-place equipment must not exceed 50% of the branch-circuit ampere rating.

• On a 20A circuit: fastened-in-place equipment limited to 10A maximum
• On a 15A circuit: fastened-in-place equipment limited to 7.5A maximum

Practical example: A window air conditioner (fastened in place) is plugged into a receptacle on a 20A general-purpose branch circuit that also supplies other receptacles. The air conditioner cannot exceed 10A (50% of 20A). If that same air conditioner were on a 20A circuit by itself with no other loads, it could draw up to 16A (80% of 20A).

30-Ampere Branch Circuits — NEC 210.23(C)

A 30A branch circuit is permitted in dwelling units only for fixed-in-place appliances, or luminaires, or combinations of these. In other than dwelling units, it may supply fixed or portable equipment. Any receptacle outlets on a 30A circuit must be rated 30 amperes — you cannot install 15A or 20A receptacles on a 30A branch circuit in most applications.

40 and 50-Ampere Branch Circuits — NEC 210.23(D)

These circuits are permitted to supply fixed cooking units, infrared heating appliances, or other fixed equipment. Any receptacle outlets on 40A or 50A circuits must be rated 40A or 50A accordingly.

Summary Table — NEC Table 210.24

Table 3: Branch Circuit Summary — Based on NEC Table 210.24 (2023 Edition, Copper Conductors)

Circuit Rating	Min. Conductor (Copper)	Max. Load (Portable Device)	Receptacle Rating Required	Typical Applications
15A	14 AWG	12A (80%)	15A or 20A	Bedrooms, living rooms, general lighting
20A	12 AWG	16A (80%)	15A or 20A	Kitchens, baths, laundry, small appliances
30A	10 AWG	24A (80%)	30A (where receptacles used)	Dryers, water heaters, fixed equipment
40A	8 AWG	32A (80%)	40A or 50A	Electric ranges, cooktops
50A	6 AWG	40A (80%)	50A	Large cooking equipment, fixed heating

Conductor Sizing and Overcurrent Protection

Conductor Sizing — NEC 210.19

Branch circuit conductors must have an ampacity not less than the maximum load to be served, and in no case less than the branch circuit rating established by the OCPD. Two additional requirements apply:

Continuous loads (NEC 210.19(A)(1)): Where a branch circuit supplies a continuous load — defined as a load expected to operate at maximum current for 3 or more hours — the conductor must be sized at not less than 125% of the continuous load plus 100% of any non-continuous load on the same circuit.

Temperature rating (NEC 110.14(C)): The conductor’s temperature rating must be compatible with the temperature rating of the terminals on the equipment. Most standard devices and panels are rated 60°C or 75°C — using 90°C-rated conductors does not allow you to apply the 90°C ampacity from Table 310.16 unless the equipment terminals are also rated for 90°C. You may use 90°C ampacity values for conductor sizing calculations, then select the final size based on the 60°C or 75°C column per the terminal rating.

Overcurrent Protection — NEC 210.20

The branch circuit overcurrent protective device must:

• Have an ampere rating not less than the load to be served
• For continuous loads: be rated not less than 125% of the continuous load plus 100% of any non-continuous load
• Comply with the specific OCPD sizing rules in NEC Article 240

These requirements mirror the conductor sizing rules. For a purely continuous load, both the conductor and the OCPD are sized at 125% of the continuous load current.

GFCI and AFCI Protection Requirements

NEC Article 210 also governs where ground-fault circuit interrupter (GFCI) and arc-fault circuit interrupter (AFCI) protection is required on branch circuits. These are among the most commonly tested topics on the journeyman exam and among the most commonly cited violations in residential inspections.

GFCI Protection — NEC 210.8

GFCI protection is required for all 125V through 250V, single-phase, 15A and 20A receptacles installed in the following locations in dwelling units (NEC 210.8(A)):

• Bathrooms
• Garages and accessory buildings with a floor at or below grade
• Outdoors
• Crawl spaces at or below grade level
• Unfinished basements
• Kitchen countertop surfaces
• Sinks — within 6 feet of the outside edge of the sink (2023 NEC)
• Boathouses
• Bathtubs or shower stalls — within 6 feet of the outside edge
• Indoor damp or wet locations
• Laundry areas

In other than dwelling units, NEC 210.8(B) extends GFCI requirements to commercial and industrial locations including bathrooms, kitchens, rooftops, outdoors, garages, and any unfinished portion of a building below grade.

AFCI Protection — NEC 210.12

Arc-fault circuit interrupter protection is required for all 120V, 15A and 20A branch circuits supplying outlets or devices in the following areas of a dwelling unit (NEC 210.12(A)):

• Kitchens and kitchenettes
• Family rooms, dining rooms, living rooms, parlors, libraries, dens
• Bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas
• All other rooms or areas of a dwelling unit

AFCI protection must be provided by a listed combination-type AFCI breaker located at the origin of the branch circuit, or by other listed AFCI devices. Note that AFCI and GFCI protection requirements can overlap — in some locations both are required simultaneously, which is why dual-function AFCI/GFCI breakers exist and are increasingly standard practice.

Conclusion

A branch circuit is the conductors between the final overcurrent device and the outlet — and its rating is set by that overcurrent device, not the conductor size. Four things to lock in:

1. The branch circuit starts at the final OCPD and ends at the outlet. Feeder conductors are upstream of that — they are not branch circuit conductors.
2. There are four branch circuit types: general-purpose, appliance, individual, and multiwire. Each has specific load and application rules under NEC Article 210.
3. The OCPD rating determines the branch circuit rating — not the wire size. A 10 AWG conductor on a 20A breaker is a 20A circuit. Upsizing conductors does not upsize the circuit rating.
4. Permissible loads have hard limits beyond total current: no single portable device exceeds 80% of circuit rating; fastened-in-place equipment on a mixed circuit cannot exceed 50% of circuit rating.

For the multiwire branch circuit rules in full detail, see our guide to Multi-Wire Branch Circuits: NEC Code Rules & Safety Requirements. For conduit fill calculations when running branch circuit conductors, use the VoltageLab Conduit Fill Calculator.

Frequently Asked Questions

What is the NEC definition of a branch circuit?

NEC Article 100 defines a branch circuit as the circuit conductors between the final overcurrent device protecting the circuit and the outlet(s). The branch circuit begins at the last breaker or fuse before the load conductors and ends at the receptacle, luminaire, or equipment connection point. Feeder conductors that supply the panel are not part of the branch circuit.

What determines the rating of a branch circuit?

The rating is determined by the maximum permitted ampere rating or setting of the overcurrent device, per NEC 210.18. The conductor size does not determine the circuit rating — the OCPD does. If 10 AWG conductors (rated 30A) are installed on a 20A breaker, the branch circuit is rated 20A, not 30A.

What are the four types of branch circuits under the NEC?

NEC Article 100 defines four types: (1) General-purpose branch circuit — supplies two or more receptacles or outlets for lighting and appliances; (2) Appliance branch circuit — supplies one or more appliance outlets with no permanently connected lighting; (3) Individual branch circuit — supplies only one piece of utilization equipment; (4) Multiwire branch circuit — two or more ungrounded conductors with voltage between them, sharing a single grounded (neutral) conductor.

Can a 15A receptacle be installed on a 20A branch circuit?

Yes. NEC 210.21(B)(1) permits 15A receptacles on a 20A branch circuit when the circuit supplies two or more receptacles (a multiple-outlet circuit). A single receptacle on a 20A individual branch circuit must be rated 20A — you cannot install a 15A single receptacle on a 20A individual branch circuit per NEC 210.21(B)(2).

What is the maximum load for a single appliance on a 20A branch circuit that also has other outlets?

Two limits apply. For cord-and-plug connected equipment not fastened in place, the maximum rating of any single device is 80% of the branch circuit rating — 16A on a 20A circuit, per NEC 210.23(B)(1). For utilization equipment fastened in place on a circuit that also supplies lighting or other receptacles, the maximum is 50% of the circuit rating — 10A on a 20A circuit, per NEC 210.23(B)(2).