General Requirements practice questions

Correct: B — None, unless rear access is needed to work on nonelectrical parts

Working space isn't required behind or beside dead-front assemblies when all connections and adjustable parts are accessible from the front, per 110.26(A)(1). The 762 mm (30 in.) figure only applies if rear access is needed for nonelectrical parts — it isn't a blanket rear-space requirement.

Correct: B — 110.3(B) — installation and use per listing instructions

110.3(B) requires equipment that is listed, labeled, or identified for a use to be installed and used according to the instructions included with that listing. 110.3(C) covers who performs listing testing, 110.3(A) covers examination factors, and 110.2 is the general approval requirement — none of those address field installation instructions.

Correct: C — The 60°C ampacity column

Per 110.14(C)(1)(a), termination provisions on equipment rated 100 A or less (or marked for 14 AWG–1 AWG) are limited to the 60°C ampacity unless the equipment is listed and identified for a higher-rated conductor. The 75°C option applies to equipment over 100 A, and sizing off the conductor's own insulation rating ignores the termination limit that 110.14(C) sets.

Correct: D — Yes, wire-binding screws or studs with upturned lugs are permitted for 10 AWG or smaller conductors

110.14(A) permits wire-binding screws or studs with upturned lugs (or the equivalent) for 10 AWG or smaller conductors. There's no stranded-only or aluminum-only restriction on this method, and it isn't limited to pressure connectors.

Correct: C — Yes, suspended ceilings with removable panels are permitted within that zone

110.26(E)(1)(a) expressly permits suspended ceilings with removable panels within the 6 ft dedicated zone. The 'adds structural strength' condition is actually what disqualifies a ceiling from being the structural ceiling that bounds the zone, not a requirement for the suspended ceiling itself, and no special AHJ approval is called for.

Correct: A — 2.6 m (8 ft 6 in.)

480 V falls in the 301–600 V range, which requires elevation of at least 2.6 m (8 ft 6 in.) under 110.27(A). The 8 ft height applies only up to 300 V, 8 ft 7 in. applies to 601–1000 V, and 10 ft is not a threshold the code sets.

Correct: B — 1200 mm, the width of the equipment

Width must be the width of the equipment or 914 mm, whichever is greater. Since the equipment is 1200 mm wide, that governs over the 914 mm default. 762 mm is the separate rear-access minimum from 110.34(A), and 2.0 m is the height requirement, not width.

Correct: A — Its interrupting rating must be at least 42,000 A at the circuit's nominal voltage

110.9 requires that equipment intended to interrupt fault current have an interrupting rating at nominal circuit voltage at least equal to the available fault current at its line terminals — here, 42,000 A. The 125% continuous-load option is a separate branch-circuit/feeder sizing rule, not an interrupting-rating rule, and neither trip-setting adjustability nor transformer impedance percentage is what 110.9 measures.

Correct: C — 110.12(A)

110.12(A) specifically addresses unused openings and requires them to be closed to restore protection equivalent to the enclosure wall. 110.12(B) instead covers contamination and physical damage to internal parts, not open knockouts.

Correct: D — A motor control center in a commercial building that must be serviced while energized

110.16(A) covers equipment such as motor control centers in other than dwelling units that is likely to require examination, adjustment, servicing, or maintenance while energized. The dwelling-unit panelboard is exempt, equipment never worked on energized doesn't meet the 'likely to require' condition, and a handheld multimeter isn't equipment of the type 110.16(A) addresses.

Correct: C — The identification and location of the circuit source supplying it

110.22(A) requires that in buildings other than one- or two-family dwellings, the marking identify and locate the circuit source feeding the disconnect, unless that's already evident. The overcurrent rating, manufacturer data, and installation date are not part of this marking requirement.

Correct: B — One entrance to and egress from the working space at each end, at least 24 in. wide and 6½ ft high

Equipment rated 1200 A or more and wider than 1.8 m (6 ft) requires one entrance to and egress from the working space at each end, not less than 610 mm (24 in.) wide and 2.0 m (6½ ft) high, per 110.26(C)(2). The 36 in. figure wrongly borrows a general clearance number instead of the entrance width. Being a non-service disconnect doesn't exempt equipment from this rule, and indoor location has no bearing on it either.

Correct: A — Marked with an orange outer finish or other effective means

110.15 requires the higher-voltage-to-ground conductor or busbar to be durably marked orange or by other effective means. The busbar is explicitly included, so the 'unmarked busbar' option is wrong. White/gray identifies the grounded conductor, and green identifies equipment grounding — neither applies here.

Correct: C — The working space depth is twice the minimum required by 110.34(A), with the entrance located at least the Table 110.34(A) clear distance from the equipment

Per 110.33(A)(1)(b), a single entrance is allowed for equipment over 1.8 m (6 ft) wide only if the working space depth is doubled and the entrance sits at least the Table 110.34(A) clear distance away, or per (A)(1)(a) if exit travel is unobstructed. Meeting the base entrance size, having a nearby personnel door, or guarding energized parts are separate requirements that don't by themselves justify a single entrance.

Correct: C — Studs and wallboard

110.31(A)(1) specifically bans studs and wallboard construction for vault walls and roof, regardless of any fire rating claimed, because it lacks the structural strength the section requires. Reinforced concrete and other rated masonry assemblies are the accepted approach.

Correct: B — The reconditioning was performed according to the original equipment manufacturer's instructions

110.20(B) gives two compliance paths for equipment not required to be listed: list or field-label it as reconditioned, or perform the reconditioning per the original manufacturer's instructions. Approval can't rest solely on the original listing (110.21(A)(2)); documentation of changes is the fallback used only when no listing path exists (110.20(C)); and any listing mark present must still be removed or made illegible (110.21(A)(2)).

Correct: C — 110.26(A)(1)

110.26(A)(4)(4) directs limited-access installations to comply with the depth requirements of Table 110.26(A)(1), so 110.26(A)(1) is where that table and its depth values are found. 110.26(A)(2) and 110.26(A)(3) cover width and height, not depth, and 110.26(B) addresses clear spaces above/below equipment, not working-space depth.

Correct: D — Service equipment for a retail strip mall

110.24(A) applies to service equipment at other than dwelling units, so the retail strip mall's service must be marked. Dwelling-unit services are excluded, industrial installations with qualified-persons-only maintenance are exempted under 110.24(B), and the rule targets service equipment specifically, not downstream branch-circuit panelboards.

Correct: D — It must be protected against weather damage during construction

Per 110.11, equipment not identified for outdoor use — including gear marked 'indoor use only' — shall be protected against damage from the weather during construction, regardless of exposure duration or a plan to relabel its enclosure type.

Correct: B — Condensation forming inside the enclosure

110.28 states enclosure types are not intended to protect against conditions such as condensation, icing, corrosion, or contamination occurring within the enclosure or entering via the raceway or unsealed openings — even when the enclosure type is otherwise rated for rain, splashing, or windblown dust.

Correct: B — Permanently affixed and not handwritten

110.21(B)(2) requires the marking to be permanently affixed to the equipment or wiring method and prohibits handwriting it (aside from variable portions). Removable or AHJ pre-approval requirements aren't part of this rule.

Correct: D — 110.36

110.36 covers circuit conductor installation methods, including the requirement that exposed lead-sheathed or braided-covering cable runs be supported to prevent physical damage to the sheath and to prevent electrolysis. 110.34(E) instead addresses elevation of unguarded live parts above working spaces, not conductor support methods.

Correct: B — 110.31(D)

110.31(D) is the specific rule addressing locking requirements for enclosed equipment based on mounting height above grade or floor when accessible to unqualified persons. 110.31(C)(1) covers general outdoor installation guarding rather than an individual enclosure's door/cover locking based on height, and 110.34(C) addresses locked rooms or enclosures for over 1000V work space, not equipment enclosure covers.

Correct: A — When first installed on-site

110.41(A) requires the design to be tested when first installed on-site. Annual retesting, waiting for a fault, or testing before AHJ submittal are not what the section specifies — the design must be available to the AHJ on request, and testing happens at initial on-site installation.

Correct: C — No, automatic means shall not be permitted to control all illumination within the working space

110.26(D) specifically prohibits automatic means from controlling all illumination in the working space — some non-automatic way to guarantee light must exist. A timer delay doesn't satisfy this, and the section doesn't require battery-backup emergency lighting.

Correct: D — They must remain in place whether or not a lock is actually installed

Per 110.25, the provisions for locking shall remain in place with or without the lock installed. The 'only while installed' option reverses this requirement, and there's no removability or hazardous-location condition in this section.

Correct: C — The manhole contains only optical fiber cables, power-limited fire alarm circuits, or Class 2/3 circuits (or has an unobstructing fixed ladder)

Per 110.75(A), the reduced 600 mm diameter applies only when the manhole has a fixed ladder that doesn't obstruct the opening, or contains only optical fiber cables, power-limited fire alarm circuits per 760.121, or Class 2/3 circuits per 725.60. Use frequency, cover weight, and occupancy type aren't factors in this rule.

Correct: C — 314.28, the same bending-space rule used for boxes and conduit bodies

At 1000 volts or less, 110.74(A) points to 314.28 for wire-bending space. The over-1000-volt rules in 314.71(A) and (B) only kick in above 1000 volts, per 110.74(B), and general equipment working space under 110.26 is a separate requirement entirely.

Correct: A — 110.26, the working space rule for installations of 1000 volts or less

480 volts is at or below the 1000-volt threshold in 110.73, so the standard 110.26 working space requirements apply. 110.34 only governs installations over 1000 volts, being below grade doesn't exempt equipment from working space rules, and 110.73 draws no distinction based on dwelling versus non-dwelling occupancy.

Correct: A — No — wooden plugs driven into masonry, concrete, or plaster are specifically prohibited

110.13(A) explicitly bans wooden plugs driven into holes in masonry, concrete, plaster, or similar materials as a mounting method, regardless of treatment or added support — an approved anchor must be used instead.

Correct: D — 110.22(C)

110.22(C) covers field marking for tested series combination systems using manufacturer-marked ratings per 240.86(B). 110.22(B) applies instead when the series rating was selected under engineering supervision (240.86(A)), and 110.21(B) is the general field-applied hazard marking requirement referenced by both but not specific to series combination systems.

Correct: A — 110.17

110.17(2) sets the requirements for identified replacement parts used during servicing and preventive maintenance (OEM-provided, engineer-designed, or AHJ-approved). 110.20 instead covers reconditioned equipment being returned to service, a different scenario than sourcing a maintenance replacement part.

Correct: A — The ampacity of the transformer's supply conductors

110.58 ties the transformer disconnect's ampere rating directly to the ampacity of the supply conductors feeding the transformer, not to the transformer's nameplate current, a 125% multiplier, or a standard breaker-size lookup.

Correct: C — Article 430, Parts III, IV, and V

110.52 directs motor-operated equipment to Article 430, Parts III, IV, and V for overcurrent protection. Article 440 covers HVAC motor-compressors specifically, not general tunnel motors, and Article 110 Part IV is just where this pointer rule lives — it doesn't set its own protection scheme.

Correct: A — Directly above the electrical equipment or conductors in the vault

110.76(A) prohibits personnel access openings directly above electrical equipment or conductors, since a fall through the opening would land on live gear. Stairway landings, ventilation sightlines, and distance from equipment aren't restricted by this rule — only the directly-over-equipment case is.

Correct: D — 110.7

110.7 requires completed wiring installations to be free from short circuits, ground faults, or unwanted grounding connections; 110.10 instead addresses circuit impedance and short-circuit current ratings of equipment, not testing the finished installation for faults, and 110.12 covers neat and workmanlike mechanical execution, a different concern than electrical fault-freedom.

Correct: D — The low-voltage equipment must be effectively separated from the high-voltage space by a partition, fence, or screen

110.26(A)(5) requires a suitable partition, fence, or screen between equipment operating at 1000 V or less and any exposed live parts over 1000 V sharing the same vault, room, or enclosure. There's no exception for de-energizing during service or for relying on aisle distance alone.

Correct: A — It's a violation — required working space cannot be used for storage

110.26(B) states working space required by this section shall not be used for storage, with no carve-out for temporary items, partial blocking, or location type. Any storage in the dedicated working space violates the rule.

Correct: A — Short-circuit the CT's secondary leads

110.23 requires unused CTs on potentially energized circuits to be short-circuited. De-energizing the primary isn't what this section addresses, and grounding the secondary doesn't prevent the open-circuit voltage buildup that shorting does — leaving it open is exactly the hazard the rule prohibits.

Correct: D — No, a plain fence must be at least 2.1 m (7 ft), or the 6 ft fence needs a 1 ft barbed-wire extension

Per 110.31, a fence alone must be not less than 2.1 m (7 ft), or a combination of 1.8 m (6 ft) or more of fence fabric plus a 300 mm (1 ft) or more barbed-wire extension. A bare 6 ft fence with nothing added falls short — it needs the extension to qualify. A vault is not required when a compliant fence is used.