SFB-7 — GFCI, AFCI, and Branch-Circuit Personnel Protection

Use the 2017 GFCI sentence, not a later expansion

A ground-fault circuit interrupter protects personnel by opening a circuit or portion of a circuit when current to ground exceeds the device's personnel-protection threshold. It compares current leaving and returning through intended conductors. It does not need an equipment grounding conductor to sense imbalance, but installing GFCI protection does not create an equipment grounding path.

Under 2017 NEC 210.8(A), all 125 V, single-phase, 15- and 20 A receptacles installed in the listed dwelling-unit locations require GFCI protection for personnel. The device must be readily accessible. Later editions expanded voltage, ampere, location, and outlet scopes; those later expansions do not control this 2017-reference exam.

The dwelling locations are:

1. bathrooms;
2. garages and grade-level portions of unfinished accessory buildings used for storage or work;
3. outdoors;
4. crawl spaces at or below grade;
5. unfinished basement portions or areas not intended as habitable rooms and limited to storage, work, or similar use;
6. kitchens, where receptacles serve countertop surfaces;
7. receptacles within 6 ft of the top inside edge of a sink bowl;
8. boathouses;
9. receptacles within 6 ft of the outside edge of a bathtub or shower stall; and
10. laundry areas.

Each numbered item has wording and, in some cases, exceptions. Read them. A receptacle in a finished dining area is not converted into an unfinished-basement receptacle because the service panel is downstairs. A kitchen receptacle that does not serve a countertop may still require GFCI because it is within 6 ft of a sink, but the correct reason and measurement matter.

Section 210.8(D) separately requires GFCI protection for outlets supplying dishwashers installed in dwelling-unit locations. “Outlet” is broader than “receptacle,” so a hard-wired dishwasher is not excluded merely because it lacks an attachment plug. This specific 2017 rule does not convert all dwelling appliance outlets into GFCI outlets.

For non-dwelling occupancies, 2017 NEC 210.8(B) likewise begins with the 125 V, single-phase, 15- and 20 A receptacle scope and then lists locations such as bathrooms, kitchens, rooftops, outdoors, sinks within 6 ft, indoor wet locations, locker rooms with associated showering facilities, garages and service bays, and crawl spaces at or below grade. A commercial kitchen does not use the later 125–250 V, 50 A-or-less scope on this exam.

Apply the 2017 AFCI scope

An arc-fault circuit interrupter is intended to protect against effects of arcing faults by recognizing characteristics of arcing and de-energizing the circuit when an arc fault is detected. It is not a conventional overload calculation and does not replace a breaker or fuse's overcurrent function unless the listed device combines functions.

Under 2017 NEC 210.12(A), all 120 V, single-phase, 15- and 20 A branch circuits supplying outlets or devices installed in dwelling-unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas require listed AFCI protection by one of the methods in the section. Bathrooms, garages, and unfinished basements are not in that dwelling list.

The phrase is outlets or devices, not receptacles only. A hard-wired lighting outlet in a listed room can be within the AFCI scope. Conversely, an outlet's presence in a dwelling does not automatically trigger AFCI if its area is not listed. Match voltage, phase, branch-circuit rating, and room or area.

A listed combination-type AFCI installed to protect the entire branch circuit is one method. The 2017 section also permits listed outlet branch-circuit AFCI arrangements and other methods when conductor length, first-outlet location, wiring method, enclosure, and product requirements are satisfied. Do not assume an AFCI receptacle placed anywhere downstream protects all upstream wiring.

Section 210.12(D) addresses branch-circuit extensions or modifications in listed dwelling and dormitory areas. Protection can be provided by a listed AFCI at the branch-circuit origin or by a listed outlet branch-circuit AFCI at the first receptacle outlet of the existing branch circuit, subject to the rule. The exception is limited to an extension not more than 6 ft that adds no outlets or devices. Replacing a device also triggers applicable replacement rules in 406.4(D).

Recognize overlapping protection

A 120 V, 20 A dwelling kitchen countertop receptacle generally needs both GFCI and AFCI protection in 2017: GFCI because it serves a countertop and AFCI because the branch circuit supplies an outlet in a kitchen. Protection can be supplied by separate compatible devices or a listed dual-function device. Passing one test does not satisfy the other function.

GFCI is not overcurrent protection. A balanced 30 A load through a 20 A GFCI device may have no current imbalance, yet it is an overload. AFCI is not a substitute for correct conductor ampacity or tight terminals. An equipment grounding conductor supplies a low-impedance fault-current path; GFCI monitors imbalance. A ground-fault protective device for equipment uses a different purpose and threshold than a Class A personnel GFCI.

For replacement of a non-grounding-type receptacle where no equipment grounding conductor exists, 406.4(D)(2) permits specified GFCI replacement options with required “GFCI Protected” and “No Equipment Ground” markings. The GFCI reduces shock risk but does not provide an equipment ground. Finish every problem by asking what is protected, what condition causes operation, which 2017 scope applies, whether the device is accessible, and whether another protection function is also required.