Special Equipment practice questions (Articles 604–670)

A manufactured wiring assembly uses cable rather than conduit. Which cable type satisfies 604.100(A)(1) for general power conductors?

1. A Type UF cable with 10 AWG to 12 AWG conductors
2. B Listed Type AC or Type MC cable with 8 AWG to 12 AWG conductors
3. C Type SE cable with 8 AWG to 10 AWG conductors
4. D Listed Type NM cable with 12 AWG to 14 AWG conductors

A manufactured wiring system uses flexible cord to connect a component to utilization equipment that is not permanently secured to the building. Which installation is compliant?

1. A A 5 ft length of 14 AWG flexible cord on a standard receptacle-fed appliance, with identified strain relief
2. B A 7 ft length of hard-usage flexible cord with 12 AWG conductors, fully visible, with identified strain relief
3. C A 5 ft length of hard-usage flexible cord with 12 AWG conductors, fully visible, with identified strain relief
4. D A 5 ft length of hard-usage flexible cord routed behind a wall panel where it is not visible

An installer wants to run a manufactured wiring system through an above-ceiling air-handling plenum. What does 604.10 require for this to be permitted?

1. A Any manufactured wiring system may be used in a plenum with no additional listing
2. B The assembly must be listed for use in air-handling spaces and installed per 300.22
3. C Plenum installation is never permitted for manufactured wiring systems
4. D Only the outdoor-listed version of the assembly may be used in a plenum

A group of interconnected freestanding office furnishings is being fed by a single flexible cord and plug. Which condition must be true for this to comply with 605.9?

1. A The assembly may use a multiwire circuit as long as the total length stays under 30 ft
2. B The receptacle supplying power is on a dedicated circuit serving only that furnishing
3. C The receptacle supplying power may also feed a nearby wall outlet on the same circuit
4. D The flexible cord may be standard hard usage type instead of extra-hard usage

A luminaire built into an office furnishing system is connected by cord and plug. Which cord characteristic is NOT required by 605.6(B)?

1. A An equipment grounding conductor, unless supplied from a listed Class 2 power source
2. B Minimum size of 12 AWG
3. C Hard usage type
4. D Length not exceeding 2.7 m (9 ft)

A modular workstation panel is being screwed and anchored directly to a wall in an open-plan office, permanently fastening it in place. Which section specifies how this office furnishing must be connected to the building electrical system?

1. A 605.8
2. B 605.4
3. C 605.7
4. D 605.9

Under NEC 605.3, a relocatable wired partition in an office is permitted by the AHJ to extend upward. What is it permitted to do?

1. A Extend to the ceiling only if the space is unoccupied
2. B Extend to the ceiling but not penetrate it
3. C Extend floor to ceiling with no restriction
4. D Penetrate the ceiling if secured to a structural member

Per 630.12(A), overcurrent protection for an arc welder is rated or set at not more than what percentage of I1max?

1. A 150 percent
2. B 125 percent
3. C 250 percent
4. D 200 percent

A seam welder is operated at different primary current values and duty cycles depending on the job. Per 630.31(A)(1), what is the minimum ampacity of its supply conductors?

1. A 70 percent of rated primary current
2. B 100 percent of rated primary current
3. C 50 percent of rated primary current
4. D The actual primary current times the Table 630.31(A) multiplier

Five arc welders are supplied by the same feeder, with individual currents already determined under 630.11(A). Per 630.11(B), what percentage of the fifth-largest (smallest) welder's current is included in the feeder ampacity calculation?

1. A 100 percent
2. B 85 percent
3. C 70 percent
4. D 60 percent

A dedicated cable tray is installed to carry only welding cables. What is the maximum allowed interval between cable supports?

1. A 1.8 m (6 ft)
2. B 150 mm (6 in.)
3. C 300 mm (12 in.)
4. D 1.2 m (4 ft)

Per 630.33, the ampere rating of a resistance welder's disconnecting means must be based on which value?

1. A The welder's rated primary current at 100% duty cycle
2. B The supply conductor ampacity determined in accordance with 630.31
3. C The nearest standard overcurrent device size above the branch-circuit rating
4. D The nameplate current rating of the control equipment alone

A shop has a single resistance spot welder rated at 40 A primary current, with dedicated supply conductors sized only for that welder (no separate welder overcurrent device installed). Which section sets the maximum rating for the overcurrent device protecting those supply conductors so it can also serve as the welder's protection?

1. A 630.32(A)
2. B 630.12(A)
3. C 630.31(A)
4. D 630.32(B)

Under 647.7(A), what protection must all 15- and 20-ampere receptacles used to connect equipment have?

1. A AFCI protection
2. B Surge protection
3. C A dedicated equipment grounding conductor only, no GFCI required
4. D GFCI protection

Per 647.6(B), where must the equipment grounding conductor for permanently wired utilization equipment and receptacles connect in the branch-circuit panelboard?

1. A Directly to the panelboard enclosure
2. B To the neutral bus shared with the grounded conductor
3. C To a ground rod local to the panelboard
4. D To an equipment grounding bus marked 'Technical Equipment Ground'

A luminaire is connected to a separately derived system operating at 60 volts to ground under Article 647. What disconnecting means arrangement satisfies 647.8(A)?

1. A A disconnect that simultaneously opens all ungrounded conductors, located within sight of the luminaire or lockable open per 110.25
2. B A plug-and-cord connection accessible from the luminaire without a dedicated switch
3. C A single-pole switch in the ungrounded conductor, located anywhere in the same room
4. D A disconnect within sight of the panelboard supplying the system, regardless of distance to the luminaire

A technical power system for a broadcast studio uses standard single-phase panelboards fed at a higher-than-normal voltage, with common-trip two-pole breakers protecting each branch circuit. Which section requires the system voltage to be marked on the panel face or inside the door and requires simultaneous disconnection of both ungrounded conductors?

1. A 647.4(B)
2. B 647.4(A)
3. C 647.6(B)
4. D 647.4(C)

A facility manager wants to install a 60/120-volt technical power system per Article 647 in a dwelling unit home office to quiet a sensitive audio workstation. Is this permitted?

1. A Yes, because the equipment is sensitive electronic equipment
2. B No, because 647.3 restricts this system to commercial or industrial occupancies
3. C No, because Article 647 systems are never permitted regardless of occupancy
4. D Yes, as long as a licensed electrician installs it

You're wiring an electronic organ installation and need to confirm the minimum size for the electromagnetic valve supply conductors versus the main common-return conductor in that supply. Which section specifies these minimum conductor sizes?

1. A 650.5
2. B 650.6(A)
3. C 650.6(B)
4. D 650.6(C)

An electrician is running 24 AWG conductors for a pipe organ's control circuit. What is the maximum rating of the overcurrent device permitted to protect these conductors?

1. A 15 amperes
2. B No overcurrent protection is required
3. C 20 amperes
4. D 6 amperes

A pipe organ installation includes digital sampled-sound reproduction equipment and amplifiers. Which article governs that equipment per 650.3(A)?

1. A Article 640
2. B Article 770
3. C Article 725
4. D Article 650, with no reference to other articles

For fixed and stationary X-ray equipment, what is required in addition to the disconnecting means?

1. A A second disconnecting means within sight of the transformer
2. B A separate control device in the control supply or high-voltage transformer primary circuit
3. C A dedicated equipment grounding conductor sized for the transformer primary
4. D A ground-fault circuit interrupter ahead of the control unit

Fixed and stationary X-ray equipment is supplied by a 30-ampere branch circuit. What wiring method is permitted?

1. A A suitable attachment plug cap with hard-service cable or power-supply cord
2. B A dedicated individual branch circuit is mandatory regardless of amperage
3. C Flexible cord connection only permitted above 1000 volts
4. D Cord-and-plug connection only if the equipment is also portable

Per 660.5, how must the disconnecting means for X-ray equipment be sized?

1. A The greater of 50% of the momentary rating input or 100% of the long-time rating input
2. B 125% of the long-time rating input only
3. C At least 100% of the momentary rating input, always
4. D The lesser of 50% of the momentary rating input or 100% of the long-time rating input

A radiography suite has three X-ray units on the same high-voltage circuit, each operated independently of the others. Per 660.24, what's required?

1. A A single high-voltage switch shared by all three units
2. B Each unit must have its own high-voltage switch or equivalent disconnecting means
3. C Only the largest unit needs a disconnecting means
4. D A shared disconnect is sufficient as long as each unit has its own overcurrent device

Under NEC 660.23(A), which safeguard is required for radiographic- and fluoroscopic-type industrial/lab equipment?

1. A A warning label posted on the equipment housing
2. B A pilot light or readable meter deflection showing the equipment is energized
3. C A lockable disconnect within sight of the equipment
4. D Effective enclosure or interlocks that automatically de-energize the equipment

Per 660.6(A), the ampacity of a branch circuit supplying a single X-ray unit must be at least:

1. A The greater of 50 percent of the momentary rating or 100 percent of the long-time rating
2. B 125 percent of the long-time rating, matching continuous-load sizing
3. C 100 percent of the momentary rating only
4. D The lesser of 50 percent of the momentary rating or 100 percent of the long-time rating

An access door on an induction heating unit provides access to internal equipment operating at 480 volts ac. Per 665.22, which is required?

1. A The disconnecting means must have mechanical lockouts, since any door on this equipment requires it
2. B No special provision is needed because 480 V is a normal utilization voltage
3. C The door must be capable of being locked closed or interlocked to de-energize the supply circuit when opened
4. D The door only needs to be fastened in a manner that makes it inconvenient to remove

An industrial induction heating installation feeds three separate induction heating machines from one supply. Two of the machines can operate simultaneously while the third stays in standby. Which section tells you how to size the supply conductors' ampacity based on nameplate ratings and standby currents?

1. A 665.10(B)
2. B 665.12
3. C 665.5
4. D 665.10(A)

A capacitor used with induction heating equipment under Article 665 is rated 480 volts. Which section governs its discharge time and means?

1. A 460.6
2. B No discharge requirement applies because the equipment is under 665
3. C 665.24 sets an independent discharge time for all capacitors regardless of voltage
4. D 460.28

A dielectric heating applicator has three sliding access panels. One electrician opens only the middle panel to inspect the work. Per 665.25, what must happen?

1. A Power is removed only from the section behind the middle panel
2. B Power stays on because the other two panels remain closed
3. C All power is removed from the applicator
4. D Power is reduced but not fully removed, since only one panel opened

Under Article 665, the converting device of a heating equipment installation must be contained within an enclosure made of what?

1. A Any rigid material rated for the voltage present
2. B Sheet metal not less than 0.5 mm thick
3. C Noncombustible material
4. D Insulating material rated for the operating frequency

A dielectric heating unit has a compartment where parts energized at 200 volts dc are exposed when the access panel is removed. What does 665.23 require?

1. A No label, since the panel is normally kept in place
2. B A label only if the voltage exceeds 600 volts
3. C A label only required on the exterior enclosure, not near the exposed parts
4. D A DANGER — HIGH VOLTAGE — KEEP OUT label plainly visible where contact could occur

A cell room in a chlor-alkali facility has motors, sensors, and control devices mounted directly on an electrolytic cell within the cell line working zone. Which section specifies the permitted wiring methods for connecting this auxiliary electrical equipment to the premises wiring system?

1. A 668.30(A)
2. B 668.30(C)
3. C 668.12
4. D 668.32(A)

According to 668.32(A), what is the grounding requirement for conductive surfaces of a crane or hoist entering the cell line working zone?

1. A Grounding is required only if the crane's surface exceeds 50 volts to ground
2. B They must be solidly grounded to the building's structural steel at all times
3. C They are not required to be grounded, though the portion contacting an energized cell or its attachments must be insulated from ground
4. D Grounding is required, but a flexible bonding jumper may substitute for a solid connection

Per 668.21(A), circuits supplying ungrounded receptacles for hand-held equipment in the cell line working zone must be supplied through what?

1. A A grounded autotransformer sized for the connected load
2. B An isolating transformer with an ungrounded secondary
3. C A double-insulated step-down transformer bonded to the equipment grounding system
4. D A GFCI-protected branch circuit from the main distribution panel

A motor-generator set supplies dc power to an electrolytic cell line, but the motor itself is not electrically connected to the cell supply system. Under 668.3(B), how must the motor branch circuit be installed?

1. A It is exempt from Articles 110, 210, 215, 220, and 225 like the cell line conductors
2. B It only needs to comply with Article 240 overcurrent rules
3. C It is exempt from Article 250 grounding only
4. D It must comply with all applicable sections of the Code, same as any ordinary motor circuit

What determines the required cross-sectional area of a cell line conductor per 668.12(B)?

1. A The ampacity value from the standard 310.16 conductor tables
2. B The voltage drop allowed over the length of the cell line
3. C A fixed minimum size set for all cell line installations regardless of load
4. D Keeping temperature rise, at maximum load and maximum ambient, within the safe operating temperature of the insulation or conductor supports

A DC cell line process power supply operates at 40 volts. Which statement is correct regarding grounding?

1. A The metal enclosures must be grounded through protective relaying because all cell line equipment exceeds the 50-volt threshold
2. B The DC conductors must be grounded because the supply operates under 50 volts
3. C A minimum 4/0 AWG copper grounding electrode conductor is required regardless of voltage
4. D The DC conductors are not required to be grounded, and the enclosure grounding rule in 668.11(B) does not apply at this voltage

An electroplating dc system is fed by three dc power supplies operating in parallel. Per 669.8(A), what is required?

1. A A single disconnecting means on the combined dc bus is sufficient
2. B A disconnecting means on the ac input of each power supply only
3. C A disconnecting means on the dc side of each power supply
4. D A disconnecting means only on the largest of the three power supplies

An electroplating system operates at 75 volts DC between the electrolyte tank and the conversion equipment. Which wiring arrangement is required for insulated conductors under 669.6(B)?

1. A Run bare, guarded against accidental contact per 110.27
2. B Run without insulated support, as long as protected from physical damage
3. C Run only in rigid metal conduit with no exposed sections permitted
4. D Run on insulated supports, protected from physical damage

Under 669.9, which method is an acceptable way to provide overcurrent protection for dc conductors supplying an electroplating process?

1. A A current-sensing device that operates a disconnecting means
2. B An unfused disconnect switch sized for the load
3. C Relying on the rectifier's voltage regulation alone
4. D A time-delay relay with no current sensing

Which of the following is NOT one of the five required items on an industrial machine's permanent nameplate under 670.3(A)?

1. A Ampere rating of the largest motor from the motor nameplate
2. B Short-circuit current rating of the machine industrial control panel
3. C Nameplate ampere rating of every motor on the machine individually listed
4. D Electrical diagram number or index number to the electrical drawings

A packaging machine has its motor branch-circuit protective devices and a single main overcurrent device furnished by the machine manufacturer, protecting the machine supply circuit. Which section specifies the maximum rating for this machine supply circuit protective device, based on the largest branch-circuit device rating plus 125% of resistance heating loads plus other motor full-load currents?

1. A 670.5
2. B 670.4(B)
3. C 670.4(A)
4. D 670.4(C)

A machine has resistance heating elements, several motors, and other apparatus on one supply conductor. Per 670.4(A), how should the highest-rated motor's full-load current be treated in the ampacity calculation?

1. A It is excluded from the calculation and sized on a separate branch circuit
2. B At 125% only if it is a continuous-duty motor
3. C At 125% of its full-load current rating
4. D At 100% of its full-load current rating, the same as the other motors