9.5 Temporary Installations (Article 590), Cranes & Hoists (Article 610), Elevators & Escalators (Article 620)

9.5 Temporary Installations (Article 590), Cranes & Hoists (Article 610), Elevators & Escalators (Article 620)

The PSI outline hides three complete NEC articles inside the General Electrical Knowledge subject area as sub-topics (j) temporary wiring, (k) cranes and hoists, and (l) elevators and escalators. Each is a Chapter 5 or Chapter 6 article whose rules supplement or modify the general Chapter 3 wiring rules, and each has two or three numbers the exam reliably asks for.

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1. Article 590 — Temporary Installations

Article 590 is a relaxation, not a loophole. It permits methods that would be unacceptable permanently, and pays for that relaxation with time limits and mandatory GFCI protection.

590.3 Time constraints

590.4 General requirements

• Services are installed in conformance with Article 230, exactly as they would be permanently.
• Feeders must originate in an approved distribution center and may be run as multiconductor cord or cable assemblies or, where not subject to physical damage, as single insulated conductors supported by the messenger or in a raceway.
• Branch circuits originate in an approved power outlet or panelboard.
• Receptacles must be of the grounding type and must be connected to an equipment grounding conductor; on construction sites, receptacles may not be installed on any branch circuit that supplies temporary lighting.
• Lamp protection. Lamps for general illumination must be protected from accidental contact by a suitable luminaire or lampholder with a guard; brass shell, paper-lined, and unprotected sockets are prohibited.
• Support. Cable assemblies and flexible cords may not be laid on the floor, must be protected where they pass through doorways or are subject to vehicle traffic, and — outside of the 590.3(B) holiday allowance — may not be supported by vegetation.
• Splices made without a box are permitted for nonmetallic multiconductor cord or cable assemblies, provided the equipment grounding continuity is maintained (590.4(G)).

590.6 Ground-fault protection for personnel — the rule that gets tested

• 590.6(A)(1): All 125-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets that are not part of the permanent wiring and are in use by personnel must have GFCI protection. There is no AEGCP substitute here.
• 590.6(A)(2): Receptacles other than those in (A)(1), up to 250 volts, must also have GFCI protection where used by personnel.
• 590.6(A)(3): Receptacles on 15 kW or smaller portable generators are addressed separately.
• 590.6(B): For receptacles other than the 125-volt 15/20/30-ampere ones, an assured equipment grounding conductor program may be used in place of GFCI protection — with written program documentation, a designated competent person, continuity testing of every cord and receptacle, and testing intervals (before first use, after repair, after suspected damage, and at least every three months).
• 590.7: A disconnecting means must be provided to allow the disconnection of all ungrounded conductors of each temporary circuit.

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2. Article 610 — Cranes and Hoists

Crane motors run on short-time duty, so crane conductors are sized from a duty-specific table rather than from Table 310.16:

• 610.14(A) sends you to Table 610.14(A) for the ampacities of insulated conductors used with short-time-rated crane and hoist motors, indexed by conductor size, temperature rating, and the duty cycle (30-minute, 60-minute, or continuous).
• Minimum size: conductors used in crane and hoist circuits are generally not smaller than 16 AWG, with narrow allowances for control circuits and for multiconductor cable within listed assemblies.
• 610.14(E) provides demand factors for conductors supplying more than one motor on a crane or hoist — the same principle as a motor feeder, adapted to intermittent hoisting duty.
• 610.13 governs the conductor types permitted, and 610.11 the wiring methods; flexible connections to moving parts use listed flexible cord or cable in a strain-relieving arrangement.
• 610.21 covers contact (collector) conductors — the rigid runway conductors or festooned cable that feed a moving bridge — including support spacing, clearance from the crane bridge, and guarding against accidental contact.
• 610.31 requires a runway conductor disconnecting means — a readily accessible, lockable disconnect, operable from the ground or floor, that opens all ungrounded runway conductors.
• 610.32 requires a disconnecting means for the crane or monorail hoist itself, located within sight of the crane or hoist, readily accessible and operable from the ground or floor level, lockable in the open position, and opening all ungrounded conductors simultaneously.
• 610.41 covers overcurrent protection of the contact conductors and the crane branch circuits.
• 610.61 requires the crane or hoist frame to be grounded. Moving parts other than removable accessories having metal-to-metal bearing surfaces are considered electrically connected through those surfaces, and the trolley and bridge frames are considered grounded through the bridge and trolley wheels and their tracks unless conditions such as paint or grease prevent reliable metal-to-metal contact — in which case a separate bonding conductor is required.

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3. Article 620 — Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts, and Stairway Chairlifts

Article 620 is where an electrician most often works alongside another trade, and its separation-of-circuits rules exist so that an elevator mechanic is never dependent on the building electrician to get light in a pit.

Branch circuits that must stand alone

Conductor sizing and demand

620.13 sizes feeders and branch circuits from the motor and controller ratings, accounting for the intermittent duty of the elevator machine. Where a single feeder supplies more than one elevator, 620.14 and Table 620.14 provide demand factors that recognize that not every car accelerates at the same instant.

Disconnecting means and coordination

• 620.51 requires a single means for disconnecting all ungrounded main power supply conductors for each unit: an enclosed externally operable fused motor circuit switch or circuit breaker, lockable in the open position, and located where it is readily accessible to qualified persons and visible from the controller (with provisions for remote machine rooms).
• 620.51(C) prohibits that disconnect from disconnecting the car lighting, receptacle, and ventilation circuits — those have their own disconnect under 620.53, which must also be lockable in the open position.
• 620.62 requires selective coordination: where more than one driving machine disconnecting means is supplied by a single feeder, the overcurrent protective devices in each disconnecting means must be selectively coordinated with any other supply-side overcurrent protective device. One stalled car may not take the whole bank down.
• 620.85 requires GFCI protection for 125-volt, single-phase, 15- and 20-ampere receptacles installed in pits, hoistways, on car tops, and in escalator and moving walk wellways, as well as in machine rooms, machinery spaces, control rooms, and control spaces.

[!IMPORTANT] The hoistway is not a chase. Under 620.21, only wiring and equipment used directly in connection with the elevator may be installed inside a hoistway, machine room, control room, machinery space, or control space. Running a building lighting circuit or a data cable through a hoistway because it is a convenient vertical path is a violation and a rejected inspection.