Cranes and Hoists practice questions

Correct: D — The conductor separation must be increased proportionately

610.21(C) allows increasing the support interval up to 12 m (40 ft) only if the separation between conductors is increased proportionately. The insulating saddle interval and rigid-conductor rules belong to 610.21(D) and 610.21(E), not this provision, and the increase is conditional, not automatic.

Correct: B — 610.42(A)

610.42(A) is the branch-circuit fuse/circuit breaker rating rule, which is based on Table 430.52(C)(1) and includes the rule to sum nameplate currents when two or more motors operate a single motion. 610.42(B)(1) instead addresses feeder taps supplying multiple motors, and 610.43(C) governs overload protection for multimotor branch circuits, not short-circuit/ground-fault sizing.

Correct: D — 610.14(A)

610.14(A) hosts Table 610.14(A), the ampacity table for insulated copper conductors used with short-time rated crane and hoist motors. 610.14(B) only covers sizing the separate conductors between controller and resistor using a rating factor, not the base ampacity table itself.

Correct: B — The conductors must have a flame-resistant outer covering or flame-resistant tape, individually or as a group

610.13(A) requires a flame-resistant outer covering, or flame-resistant tape applied individually or as a group, for conductors exposed to external heat or connected to resistors. Conduit, derating, and switching to bare contact conductors are not the rule this section states.

Correct: B — Rigid metal conduit

610.11(C) permits flexible metal conduit, liquidtight flexible metal conduit, liquidtight flexible nonmetallic conduit, multiconductor cable, or an approved nonmetallic flexible raceway. Rigid metal conduit is a fixed raceway and cannot provide the flexibility this section requires.

Correct: A — 300 percent

610.53 sets the general control-circuit protection allowance at not more than 300 percent of conductor ampacity. 200 percent is the tighter limit that applies specifically to transformer-tap secondaries under 610.53(A), not the general rule. 125 percent is a common continuous-load multiplier from other NEC contexts, not this section.

Correct: A — Both the 50% combined and 75% single-motion thresholds must be met; the larger required rating governs

610.33 sets two independent minimums: not less than 50% of the combined short-time rating of all motors, and not less than 75% of the short-time rating for any single motion. Both are mandatory floors, so the disconnect must satisfy whichever produces the higher required ampere rating.

Correct: B — An individual controller

610.51 requires each motor to have an individual controller unless 610.51(A) or (B) permits otherwise. A combined-horsepower shared controller and a disconnect-only setup are not what the base rule requires, and a 125%-rated controller conflates controller rating with overcurrent sizing, which isn't the topic of this section.

Correct: C — Only when every condition of 610.21(F) is satisfied, including an insulating transformer and a 300-volt maximum

610.21(F) permits this only when all four numbered conditions are met together. The rule applies to ac systems specifically, and isolating the rail from the structure isn't required — the fittings that suspend or attach the rail to a building are explicitly permitted to ground it.

Correct: A — Type NM cable

610.11 lists raceway, Type AC cable with an insulated equipment grounding conductor, Type MC cable, or Type MI cable as the permitted enclosure methods. Type NM cable is not one of the listed options, so it does not comply.

Correct: C — 100 percent of the motor nameplate full-load ampere rating

610.14(E)(1) requires 100 percent of the single motor's nameplate full-load ampere rating. The 125 percent figure is a common motor-branch-circuit factor from Article 430, not the crane single-motor rule in this concept, and the 50 percent figure only applies to the next-largest motor when multiple motors share a crane per 610.14(E)(2).

Correct: B — 610.43(A)

610.43(A)(1) states a single motor is considered protected where the branch-circuit overcurrent device meets the rating requirements of 610.42 — that's the overload-protection rule, not 610.42(A) itself, which only sets the fuse/breaker rating. 610.43(C) and 610.43(D) address multimotor and hoist-specific overload schemes, not the single-motor case.

Correct: C — A box or terminal fitting with a separately bushed hole for each conductor, without taps or splices

610.12(A) requires a separately bushed hole for each conductor and explicitly bars use at luminaire outlets for the bushing-alone method under 610.12(B) — a luminaire outlet still needs the box with individually bushed holes, and it can't contain taps or splices. A single shared bushed opening does not meet the 'separately bushed hole for each conductor' requirement.

Correct: D — It must open all ungrounded conductors simultaneously

610.31 requires the disconnecting means to open all ungrounded conductors simultaneously. Switching conductors independently, requiring elevated-only access, or gating the requirement on horsepower are not what the section allows — the disconnect must be readily accessible from ground or floor level for every runway installation covered.

Correct: B — One-third the ampacity of the branch circuit

Under 610.42(B)(1), each tap conductor to an individual motor on a shared branch circuit must have an ampacity not less than one-third that of the branch circuit — not one-half, not matched to the branch circuit conductors, and not based on the largest motor's full-load current.