Construction: 23 skills, step by step

Answer: B. 12 ft

For systems not over 300 volts to ground, 12 ft applies over residential property and driveways. 10 ft is limited to areas accessible to pedestrians only at not over 150 volts to ground, 15 ft applies where the voltage exceeds 300 volts to ground, and 18 ft applies over public streets, alleys and areas subject to truck traffic.

Reference: NEC 230.24(B) (NEC 2026)

Answer: C. 6

The general rule allows not more than six service disconnects for each service, grouped at one location. More than six requires a single main disconnect ahead of them.

Reference: NEC 230.71(B) (NEC 2026)

Answer: C. 7 ft (the height of the equipment)

The working space must be clear from the floor to a height of 6 1/2 ft or the height of the equipment, whichever is greater. Here the switchboard is 7 ft tall, so 7 ft governs.

Reference: NEC 110.26(A)(3) (NEC 2026)

Answer: A. A grounded (neutral) conductor for the circuit

Where switches control lighting loads supplied by a grounded general-purpose branch circuit, the grounded conductor must generally be provided at the switch location. The exceptions (for example a raceway or an accessible framing cavity that allows it to be added later, or a switch that does not serve a habitable room or bathroom) do not apply to this bedroom. The rule supports electronic switches such as occupancy sensors and timers.

Reference: NEC 404.2(C) (NEC 2026)

Answer: A. A cord-suspended pendant luminaire hanging 2 ft horizontally from the bathtub rim and 6 ft above it

Cord-connected, chain-, cable- or cord-suspended luminaires, pendants, lighting track and ceiling-suspended fans may not be located within the zone 3 ft horizontally and 8 ft vertically from the top of the bathtub rim or shower threshold. The pendant in option 1 is inside that zone; the others are outside it.

Reference: NEC 410.10(D) (NEC 2026)

Answer: B. At least one receptacle outlet at the front and one at the back, each readily accessible from grade and not more than 6 1/2 ft above grade

A one-family dwelling at grade needs at least one outdoor receptacle outlet at the front and at the back, readily accessible from grade and not more than 6 1/2 ft above grade. Decks and balconies carry their own separate requirement.

Reference: NEC 210.52(E)(1) (NEC 2026)

Answer: A. Within 3 ft of the outside edge of the basin

At least one receptacle outlet must be within 3 ft of the outside edge of each basin, on a wall or partition adjacent to it, on the basin countertop, or on the side or face of the basin cabinet within the permitted distance below the countertop.

Reference: NEC 210.52(D) (NEC 2026)

Answer: B. The box must be listed and marked by the manufacturer as suitable for fan support, and the fan may not exceed the listed weight (70 lb maximum)

A box used as the sole support of a ceiling-suspended fan must be listed and marked as suitable for that purpose, and may not support a fan weighing more than 70 lb (a box for a fan over 35 lb must also be marked with the weight it supports). Depth and volume alone do not qualify a box.

Reference: NEC 314.27(C) (NEC 2026)

Answer: C. 10 ft

Rigid metal conduit is generally supported at intervals not exceeding 10 ft, and securely fastened within 3 ft of each outlet box, junction box, cabinet or conduit termination. Longer spans are permitted only under the specific conditions the article lists.

Reference: NEC 344.30(A) and (B) (NEC 2026)

Answer: C. A substitute for the fixed wiring of a structure

Flexible cord may not be used as a substitute for the fixed wiring of a structure. Pendants, portable appliance connections and luminaire wiring are all among the permitted uses.

Reference: NEC 400.12 (NEC 2026)

Answer: C. 16 A

On a 15- or 20-ampere branch circuit supplying two or more outlets, one cord-and-plug-connected piece of equipment not fastened in place may not exceed 80% of the branch-circuit rating: 0.80 x 20 A = 16 A.

Reference: NEC 210.23(B)(1) (NEC 2026)

Answer: B. At least one receptacle outlet at the front and one at the back, each readily accessible from grade and not more than 6 1/2 ft above grade

A one-family dwelling at grade needs at least one outdoor receptacle outlet at the front and at the back, readily accessible from grade and not more than 6 1/2 ft above grade. Decks and balconies carry their own separate requirement.

Reference: NEC 210.52(E)(1) (NEC 2026)

Answer: A. Within 3 ft of the outside edge of the basin

At least one receptacle outlet must be within 3 ft of the outside edge of each basin, on a wall or partition adjacent to it, on the basin countertop, or on the side or face of the basin cabinet within the permitted distance below the countertop.

Reference: NEC 210.52(D) (NEC 2026)

Answer: B. The water pipe must be supplemented by an additional electrode of a type recognized by the Code

A metal underground water pipe can serve as an electrode, but the Code always requires it to be supplemented by another recognized electrode (for example a rod or a concrete-encased electrode), because the piping may later be replaced with plastic. A dielectric union would interrupt the electrode path.

Reference: NEC 250.53(D)(2) (NEC 2026)

Answer: A. Ground-fault protection of equipment

Feeder disconnects rated 1,000 amperes or more on solidly grounded wye systems of more than 150 volts to ground need ground-fault protection of equipment unless it is already provided on the supply side or an exception applies; a 480Y/277-volt system (277 volts to ground) is inside the covered voltage range. GFCI and AFCI devices protect people and branch circuits, not large feeders.

Reference: NEC 215.10; NEC 230.95 (NEC 2026)

Answer: B. By phase or line and by system at every termination, connection and splice point, with the method documented or posted at each feeder panelboard

Where more than one nominal voltage system exists, feeder ungrounded conductors are identified by phase or line and by system at all termination, connection and splice points. The Code does not fix a color scheme; the chosen method must be documented where it is readily available or posted at each feeder panelboard.

Reference: NEC 215.12(C)(1) (NEC 2026)

Answer: A. Class I, Division 1

Class I covers flammable gases and vapors. Division 1 applies where ignitable concentrations can exist under normal operating conditions; Division 2 is for abnormal conditions only. Class II is combustible dust and Class III is ignitable fibers.

Reference: NEC 500.5(B)(1) (NEC 2026)

Answer: A. It can be reached quickly for operation or inspection without climbing over or removing obstacles, using tools other than keys, or using a portable ladder

Readily accessible is the stricter of the access definitions: ready access must not depend on climbing, moving obstacles, tools (other than keys) or portable ladders. Option 2 is the old pre-2020 wording of plain 'accessible (as applied to equipment)', which today only means the equipment can be reached for operation, renewal and inspection; option 3 is 'in sight from', and option 4 is a height limit for switch and overcurrent device handles, not a definition.

Reference: NEC Article 100 (Accessible, Readily) (NEC 2026)

Answer: B. 12 ft

For systems not over 300 volts to ground, 12 ft applies over residential property and driveways. 10 ft is limited to areas accessible to pedestrians only at not over 150 volts to ground, 15 ft applies where the voltage exceeds 300 volts to ground, and 18 ft applies over public streets, alleys and areas subject to truck traffic.

Reference: NEC 230.24(B) (NEC 2026)

Answer: C. 6

The general rule allows not more than six service disconnects for each service, grouped at one location. More than six requires a single main disconnect ahead of them.

Reference: NEC 230.71(B) (NEC 2026)

Answer: A. Ground-fault protection of equipment

Feeder disconnects rated 1,000 amperes or more on solidly grounded wye systems of more than 150 volts to ground need ground-fault protection of equipment unless it is already provided on the supply side or an exception applies; a 480Y/277-volt system (277 volts to ground) is inside the covered voltage range. GFCI and AFCI devices protect people and branch circuits, not large feeders.

Reference: NEC 215.10; NEC 230.95 (NEC 2026)