Equipment Over 1000 Volts ac, 1500 Volts dc, Nominal practice questions

Correct: D — A permanent single-line diagram of the local switching arrangement showing each high-voltage connection point

495.25(B) requires a permanent, legible single-line diagram of the local switching arrangement, clearly identifying each point of connection to the high-voltage section, in addition to the sign required by 495.25(A). A lockable handle, a utility-point sign, and a short-circuit rating nameplate are not what this section calls for.

Correct: B — Not less than 100% of the total load, on an individual branch circuit

495.72(A) requires an individual branch circuit rated not less than 100% of the total load — no continuous-load 125% multiplier and no demand-factor reduction apply here, unlike typical branch-circuit sizing rules elsewhere in the Code.

Correct: D — It must be operable from a location outside the enclosure, away from energized parts

495.44(C) requires the switching mechanism to be operated from outside the enclosure where the operator isn't exposed to energized parts, and to open all ungrounded conductors simultaneously with a single operation — not in sequence or partially.

Correct: B — The door must be locked, and a DANGER — HIGH VOLTAGE — KEEP OUT sign must be installed

495.35(A) requires doors giving unqualified persons access to high-voltage parts to be locked, plus a permanent sign reading exactly DANGER — HIGH VOLTAGE — KEEP OUT for access over 1000 volts, per 110.21(B). A generic CAUTION sign doesn't meet the required wording, locking isn't optional, and the requirement isn't limited to outdoor equipment.

Correct: C — If the compartment door is interlocked with the high-voltage switch and any energized high-voltage parts are barrier-protected

495.35(B) requires both the interlock (preventing the door from opening while the HV switch is closed or the disconnect is connected) and barrier protection of any HV parts that remain energized. Relay voltage rating, mounting distance, and warning labels don't satisfy the rule.

Correct: C — A metallic enclosure with a grounding connection to the machine frame

495.65 requires a metallic enclosure for the power cable terminals, and that enclosure must include terminal connections to the machine frame for the equipment grounding conductor. A nonmetallic or ungrounded metallic enclosure, even if weatherproof or paired with a shielded cable, does not satisfy this requirement.

Correct: D — A diagram is not required for this configuration

495.48(B) specifically exempts a single cubicle or metal-enclosed substation with only one high-voltage switching device from the diagram requirement. The off-site storage, utility-request, and partial-content options aren't recognized exceptions — a required diagram must be on-site, permanent, and complete.

Correct: B — 3-phase, 4-wire, solidly grounded wye system

495.71 requires boilers to be supplied only from a 3-phase, 4-wire, solidly grounded wye system, or isolating transformers arranged to provide one. High-resistance grounding limits fault current rather than solidly grounding the system, and single-phase or ungrounded delta arrangements don't meet the requirement at all.

Correct: C — Only when the mechanism is fully charged

495.45(A) requires the breaker to be designed so stored energy cannot be released unless the mechanism has been fully charged. Withdrawal position, de-energized status, and maintenance timing are not the governing condition under this section.

Correct: B — 1.7 m (66 in.)

Under 495.41(A), the default readily-accessible height for routine handles is 2.0 m (6 ft 7 in.), but once operating force exceeds 23 kg (50 lb), the limit drops to 1.7 m (66 in.) in either the open or closed position. The portable-platform allowance in 495.41(B) applies only to infrequently operated devices, not routine transfer switch handles.

Correct: B — It is hinged and bolted or locked rather than fully removable

495.38 exempts cover plates from the 1.1 m2 (12 ft2) / 27 kg (60 lb) limits only when they are hinged and bolted or locked instead of fully removable. A lifting handle is required on removable plates regardless, and it doesn't remove the size/weight cap. Transparent material is the requirement for inspection windows under 495.40, not cover plates. Door stops are a separate requirement for external hinged doors, unrelated to the cover plate exemption.

Correct: D — A sign warning against opening the switch under load

Per 495.22, an isolating switch not interlocked with an approved circuit-interrupting device shall have a sign warning against opening it under load. Draw-out switchgear is only an alternative when no isolating switch is used at all, not a mandated replacement, and the rule doesn't require a second switch or a load-break rating.

Correct: A — Field-fabricated installations with bare live conductors

495.24 states the Table 495.24 clearances apply to field-fabricated installations of bare live conductors. It expressly excludes interior portions and exterior terminals of equipment that's designed, manufactured, and tested to accepted national standards, since that spacing is already verified at the factory.

Correct: A — Article 230, Part VIII

495.61(D) explicitly requires the disconnecting means to meet Part VIII of Article 230 (service disconnect requirements). Article 225 Part II covers outdoor branch circuits and feeders, Article 250 Part III covers grounding electrode conductors, and Article 240 Part I covers general overcurrent protection — none apply here.

Correct: B — Grounded metal cabinets or enclosures, locked to authorized and qualified persons

495.63 requires grounded metal cabinets or enclosures, locked so only authorized and qualified persons can enter. Nonmetallic enclosures, unlocked access for emergencies, and open access to all personnel all fail the grounding and locking requirement in this section.

Correct: D — Short-circuit and locked-rotor protection

495.62 is explicit that the branch-circuit protective device(s) must still provide short-circuit and locked-rotor protection — only overload protection can be waived, and only under the stated thermal-rating condition. Dropping all overcurrent protection or requiring separate integral thermal protection isn't what the section calls for.