4.1 Branch Circuit Requirements (Article 210)

Why Article 210 Is the Backbone of the Exam

A branch circuit is the portion of the wiring system extending past the final overcurrent device to the outlets it serves. Article 210 governs their ratings, conductors, receptacle spacing, and shock/fire protection. On the Virginia Journeyman exam, almost every load-calculation or device-wiring question is anchored in a 210 rule, so memorizing the section numbers is high-value.

Branch-Circuit Ratings and Conductors

NEC 210.3 lists the standard branch-circuit ratings: 15, 20, 30, 40, and 50 A. The conductors and receptacle ratings must match the circuit — a 20A circuit needs 20A-rated receptacles on a 20A-rated conductor. Per 210.19(A), branch-circuit conductors must have an ampacity not less than the maximum load to be served. The minimum conductor sizes are 14 AWG copper for 15A circuits and 12 AWG copper for 20A circuits.

The 125% Continuous-Load Rule

A continuous load is one expected to operate at maximum current for 3 hours or more (Article 100). Branch-circuit conductors for continuous loads must be sized at 125% of the continuous load [210.19(A)(1)], and overcurrent protection must likewise be rated at 125% [210.20(A)]. When a circuit combines continuous and noncontinuous loads, size the conductor at 125% of the continuous portion plus 100% of the noncontinuous portion.

Worked example — 20A branch circuit for a continuous load: A 16A continuous load (e.g., a commercial heater). 16 A × 1.25 = 20 A. A 20A breaker on 12 AWG copper (rated 20 A at 75°C terminal) is code-compliant. If the load were 17 A, then 17 × 1.25 = 21.25 A, requiring a 25A or larger breaker and larger conductors — a 20A circuit would be a violation.

Receptacle Outlet Spacing in Dwellings (210.52)

NEC 210.52 sets the maximum wall-space spacing for general-purpose receptacles in dwelling units. Key rules:

• General rooms: receptacles every 12 ft of wall space (no point on the floor line more than 6 ft from a receptacle).
• Hallways 10 ft or longer: at least one receptacle.
• Kitchen countertops: receptacles so no point on the countertop is more than 24 in from a receptacle; counter spaces 12 in. or wider require a receptacle.
• Bathrooms: at least one receptacle within 36 in. of each basin.
• Outdoor outlets: at least one accessible front and back [210.52(E)].
• Small-appliance branch circuits: two or more 20A circuits serving kitchen/dining receptacles [210.11(C)(1)].

GFCI Protection (210.8)

The 2020 NEC significantly expanded 210.8(A) for dwelling units. It now covers all 125V through 250V receptacles supplied by single-phase branch circuits rated 150 V or less to ground (the old 15A/20A, 125V cap is gone). The 11 listed locations are:

210.8(F) (new in 2020) extends GFCI to all outdoor outlets (hard-wired too, not just receptacles) on single-phase circuits 150 V-to-ground or less, 50A or less, with exceptions for snow-melt/de-icing equipment and lighting outlets not covered by 210.8(C).

For other-than-dwelling units, 210.8(B) covers 125V-250V receptacles on single-phase circuits 150 V-to-ground or less, 50A or less, and three-phase circuits 150 V-to-ground or less, 100A or less.

AFCI Protection (210.12)

210.12(A) requires listed combination-type or equivalent AFCI protection on all 120V, single-phase, 15A and 20A branch circuits supplying outlets or devices in these dwelling-unit rooms:

Kitchen, family room, dining room, living room, parlor, library, den, bedroom, sunroom, recreation room, closet, hallway, laundry area, and similar rooms/areas.

Notably not listed (AFCI not required under 210.12(A)): bathrooms, garages, unfinished basements, and outdoors — though those areas carry GFCI requirements under 210.8. Six permitted installation methods are in 210.12(A)(1) through (6); the most common is a combination-type AFCI breaker at the panel.

Ground-Fault vs Arc-Fault — Know the Difference

• GFCI protects people from shock by tripping on a ground-fault current imbalance (4-6 mA threshold for Class A devices).
• AFCI protects the structure from fire by recognizing arcing-fault signatures (parallel and series arcs) that a breaker or fuse cannot detect.

A bedroom receptacle needs AFCI; a bathroom receptacle needs GFCI; a kitchen countertop receptacle needs both. Virginia exam trap questions love listing a 210.8 location and asking which protection applies.

Multiwire Branch Circuits (210.4)

A multiwire branch circuit has two or more ungrounded conductors sharing a common neutral. Per 210.4(A), each ungrounded conductor must terminate on a separate phase so the neutral carries only the unbalanced load, and all conductors of a multiwire circuit must originate from the same panelboard. 210.4(D) additionally requires the ungrounded and grounded conductors of each multiwire branch circuit to be grouped by cable ties or similar means at the point of origin. Do not look for this material in 210.10 — that section covers ungrounded conductors tapped from grounded systems. Where a multiwire circuit supplies devices on a single yoke (like a split-wired duplex receptacle), the ungrounded conductors must have a listed handle tie or common trip so they disconnect simultaneously — protecting the next electrician who services the receptacle.