Final Exam 1 for 2023 Master Electrician

Given: After all demand factors have been taken into consideration for an office building, the demand load is determined to be 90,000 VA; the building has a 120/240-volt, single-phase electrical system. What minimum size copper conductors with THHN/THWN insulation are required for the ungrounded service-lateral conductors? Consider all termination lugs are rated for 75°C.

500 kcmil

I = P ÷ E I = 90,000 VA ÷ 240 volts = 375 amperes

Size 500 kcmil THHN/THWN 75°C rated CU conductors with an ampacity of 380 amperes should be selected from Table 310.16

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Fill in the blank:

Given: A commercial building is to be supplied from a transformer having a 480Y/277-volt, 3-phase primary and a 208Y/120-volt, 3-phase secondary.The secondary will have a balanced computed demand load of 416 amperes per phase. The transformer is required to have a kVA rating of at least _________.

150 kVA

VA = 416 amperes x 208 volts x 1.732 = 149,866 VA 149,866
VA ÷ 1,000 = 149.8 kVA

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Fill in the blank:

The Code defines a device that provides protection for PV system dc circuits by detecting a ground-fault and could interrupt the fault path in the dc circuit as a _________.

ground-fault detector-interrupter, dc

(GFDI)

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Fill in the blank:

The branch circuit conductors supplying one or more units of information technology equipment shall have an ampacity of not less than _________ of the connected load.

125%

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In regard to a 7½ hp, 480-volt, 3-phase ac motor with an 80 percent power factor and a full-load ampere rating of 19 amperes indicated on the nameplate, and a service factor of 1.15; when the initial setting of the overload device you have selected is not sufficient to carry the load, what is the maximum setting permitted for the overload protection?

26.60 amperes

19 amperes x 140% = 26.60 amperes

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Fill in the blank:

The ampacity adjustment factors for conductors addressed in Section 310.15(C)(1) of the NEC® are not required to be applied when the conductors are installed in a metal wireway unless, the number of current-carrying conductors within the wireway exceeds at least _________ at any cross-section area of the wireway.

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What minimum voltage is required for a period of up to 1½ hours to serve emergency lighting from a storage battery when the normal source voltage of 120 volts is interrupted?

105 volts

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Determine the maximum ampere setting permitted for an overload protective device responsive to motor current, where used to protect a 20hp, 240-volt, 3-phase, induction type ac motor with a temperature rise of 42 deg. C and a FLA of 54 amperes indicated on the nameplate.

70.2 amperes

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Where Type SRD multi conductor cable consist of size 8 AWG conductors and only two (2) conductors in the cable are current-carrying, what is the ampacity of the conductors?

40 amperes

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Fill in the blank:

Aluminum or steel cable trays shall be permitted to be used as equipment grounding conductors, provided _________.

I. the cable tray sections and fittings are identified as an equipment grounding conductor
II. the cable tray sections and fittings are durably marked to show the cross-sectional area of the metal

both I and II

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Fill in the blank:

When intermediate metal conduit (IMC) is threaded in the field, standard cutting die with a _________ taper per ft. shall be used.

3/4 in.

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What is the required on-site generator size, in kW, supplying a 100-ampere 480-volt, 3-phase, non-continuous load with an 80% power factor?

66.5 kW

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Fill in the blank:

When an air-conditioning equipment disconnect with a hinged door that exposed energized parts when opened is located outdoors and readily accessible to unqualified persons, the disconnect must be _________.

require a tool to open or capable of being locked

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What are the three separate branches of the Type 1 essential electrical system of a hospital?

energy storage
critical
patient-care

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Fill in the blank:

Ceiling-suspended luminaires (lighting fixtures) or paddle fans located _________ or more above the maximum water level of an indoor installed spa or hot tub shall not require GFCI protection.

12 feet

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When flat conductor cable (FCC) is used for general-purpose branch circuits, the maximum rating of the circuits shall be _________.

20 amperes

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Fill in the blank:

When sizing overcurrent protection for fire pump motors, the device(s)shall be selected or set to carry indefinitely the _________ of the motor.

locked-rotor current

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Under which, if any, of the following conditions is the neutral conductor to be counted as a current-carrying conductor?

I. When it is only carrying the unbalanced current from other conductors of the same circuit.
II. When it is the neutral conductor of a 3-phase, wye-connected system that consist of nonlinear loads.

II only

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In general, all mechanical elements used to terminate a grounding electrode conductor or bonding jumper to a grounding electrode shall be accessible. Which of the following, if any, is/are exception(s) to this rule?

I. A connection to a concrete encased electrode.
II. A compression connection to fireproofed structural metal.

both I and II

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For other than listed low-voltage luminaires not requiring grounding, all electrical equipment within a fountain or within _________ of the inside wall of a fountain shall be grounded.

5 feet

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I. A connection to a concrete encased electrode.
II. A compression connection to fireproofed structural metal.

II only

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Fill in the blank:

Each multiwire branch circuit shall be provided with a means that will _________ at the point where the branch circuit originates.

simultaneously disconnect all ungrounded conductors

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Fill in the blank:

When calculating the total load for a mobile home park before demand factors are taken into consideration, each individual mobile home lot shall be calculated at a minimum value of _________.

16,000 VA

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If a single grounding electrode, such as a ground rod, pipe, or plate, has a resistance to ground greater than 25 ohms, what additional grounding method(s) can be used to supplement it?

a concrete-encased electrode
a ground ring
the metal frame of the building

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# Fill in the blank: It shall be permissible to compute the feeder and service loads for dwellings using the optional method of calculations for dwellings instead of the general method of calculations for dwellings, if the dwelling unit is supplied with a single-phase, 120/240-volt service and the load is at least \_\_\_\_\_\_\_\_\_ or greater.

100 amperes

# Fill in the blank: In the critical care (Category 1) spaces of a healthcare facility, each patient bed location shall be provided with a minimum of \_\_\_\_\_\_\_\_\_”hospital grade” receptacles.

fourteen

# Fill in the blank: Nonmetallic surface extensions shall be permitted to be run in any direction from an existing outlet, but not within \_\_\_\_\_\_\_\_\_ of the floor level.

2 in.

The NEC® permits a building to have more than one service when: I. the load requirements of the building are at least in excess of 800 amperes. II. the building is separated by firewalls with a four-hour rating.

neither I nor II

In the garage of a dwelling unit, a 125-volt, single-phase, 15 ampere,receptacle installed in the ceiling provided for the garage door opener must be: I. a single receptacle II. GFCI protected for personnel

II only

# Fill in the blank: Underground installed service conductors that are not encased in concrete and buried 18 inches or more below grade level, shall have their location identified by a warning ribbon placed at least \_\_\_\_\_\_\_\_\_ above the underground installation.

12 in.

# Fill in the blank: Outlets supplying permanently installed swimming pool pump motors from single-phase, 15- or 20-ampere, 120- or 240-volt branch circuits, shall be provided with Class A GFCI protection where \_\_\_\_\_\_\_\_\_.

any of the above conditions exist

# Fill in the blank: The branch circuit conductors supplying a 240-volt, single-phase, 15 kW rated fixed electric space heater provided with a 10 ampere blower motor are required to have an ampacity of \_\_\_\_\_\_\_\_\_.

91 amperes

A commercial kitchen is to contain the following listed cooking related equipment: * one - 14 kW range * one - 5.0 kW water heater * one - 0.75 kW mixer * one - 2.5 kW dishwasher * one - 2.0 kW booster heater * one - 2.0 kW broiler Determine the demand load, in kW, after applying the demand factors for the kitchen equipment.

19.00 kW ## Footnote 14.00 kW - range 5.00 kW - water heater 0.75 kW - mixer 2.50 kW - dishwasher 2.00 kW - booster heater 2.00 kW - broiler 26.25 kW - total connected load x 65% = 17.06 kW NOTE: However, the NEC® states the demand shall not be less than the two largest pieces of equipment. 14.00 kW + 5.00 kW = 19 kW demand

# Fill in the blank: When two (2) ground rods are used to form the entire grounding electrode system of a building, the grounding conductor that bonds the two rods together shall not be required to be larger than size \_\_\_\_\_\_\_\_\_ copper,regardless of the size of the service-entrance conductors.

6 AWG

A kitchen with a total demand load of 54,000 VA is to be added to an existing church. The electrical system is 208Y/120-volts, 3-phase. What Size THWN copper feeder conductors are required for the kitchen addition?

1/0 AWG

# Fill in the blank: A feeder at a school welding shop is to supply the following listed transformer arc welders all with a 50 percent duty cycle. * two (2) with 60 amperes rated primary current * two (2) with 50 amperes rated primary current * two (2) with 40 amperes rated primary current The feeder is required to have an ampacity of at least \_\_\_\_\_\_\_\_\_.

176 amperes ## Footnote 60 amperes x .71 = 43 amperes x 100% = 43 amperes 60 amperes x .71 = 43 amperes x 100% = 43 amperes 50 amperes x .71 = 36 amperes x 85% = 31 amperes 50 amperes x .71 = 36 amperes x 70% = 25 amperes 40 amperes x .71 = 28 amperes x 60% = 17 amperes 40 amperes x .71 = 28 amperes x 60% = 17 amperes TOTAL = 176 amperes

# Fill in the blank: Where a 125-volt, single-phase, 20-ampere rated receptacle outlet is installed in a residential laundry room and designated for the clothes washing machine, the receptacle outlet must be provided with \_\_\_\_\_\_\_\_\_.

both AFCI and GFCI protection

What is the maximum balanced demand load, in VA, permitted to be connected to a new service of a commercial building were given the following conditions? * The service is 208Y/120 volts, 3-phase, with a 600-ampere rated main circuit breaker. * The maximum load must not exceed 80 percent of the ampere rating of the main circuit breaker.

172,923 VA

Determine the maximum standard size overcurrent protection permitted for the primary and secondary side of a transformer, when primary and secondary overcurrent protection is to be provided, given the following related information. * 150 kVA rating * Primary - 480 volt, 3-phase, 3-wire * Secondary - 208Y/120 volt, 3-phase, 4-wire

Primary - 450 amperes, Secondary - 600 amperes

Which of the following listed is considered a Class III, Division 2 location? a. A grain storage silo. b. A petroleum tank farm. c. The area of a textile mill where cotton is processed. d. A warehouse where cotton bales are stored.

d. A warehouse where cotton bales are stored.

# Fill in the blank: When buried raceways pass under streets, roads or driveways, the minimum cover requirements \_\_\_\_\_\_\_\_\_.

do not change in regard to wiring methods used

# Fill in the blank: For capacitors over 1000 volts, a means shall be provided to reduce the residual voltage to \_\_\_\_\_\_\_\_\_ after the capacitor is disconnected from the source of power.

50 volts or less within 5 minutes

# Fill in the blank: Where used outside of a, building, aluminum or copper-clad aluminum grounding electrode conductors shall not be terminated within \_\_\_\_\_\_\_\_\_ of the earth.

18 in.

Where installed for a commercial occupancy, determine the minimum size THWN copper conductors required from the terminals of a 3-phase,277/480-volt, 4-wire, on-site 200 kW generator to the first distribution device(s) containing overcurrent protection. Assume the design and operation of the generator does not prevent overloading.

300 kcmil

# Fill in the blank: Enclosures containing circuit breakers, switches and motor controllers located in Class II, Division 2 locations, shall be \_\_\_\_\_\_\_\_\_ or otherwise identified for the location.

dust tight

# Fill in the blank: Information technology equipment is permitted to be connected to a branch circuit by flexible cord-and-attachment plug cap, if the cord does not exceed \_\_\_\_\_\_\_\_\_ in length.

15 feet

# Fill in the blank: Where required, conduit seals installed in Class I, Division 1 & 2 locations shall have the minimum thickness of the sealing compound not less than the trade size of the sealing fitting and, in no case less than \_\_\_\_\_\_\_\_\_ thick.

5/8 in.

Given: A one-family dwelling to be built will have 4,000 sq. ft. of livable space, a 600 sq. ft. garage, a 400 sq. ft. open porch, a 2,000 sq. ft.unfinished basement (adaptable for future use), three (3) small-appliance branch-circuits and a branch circuit for the laundry room. Determine the demand load, in VA, on the ungrounded service-entrance conductors for the general lighting and receptacle loads using the standard method of calculation for a one-family dwelling.

10,350 VA

Determine the minimum size Type SOW flexible cord that may be used to supply a 30 hp, 3-phase, 480-volt, continuous-duty, ac motor from the motor controller to the motor terminations. Assume voltage-drop and elevated ambient temperature are not considerations.

4 AWG

# Fill in the blank: Portable structures for fairs, carnivals and similar events shall not be located under and no closer than \_\_\_\_\_\_\_\_\_ horizontally of conductors operating in excess of 600 volts.

15 feet

Under what condition is it permitted to attach flexible cords and cables to building surfaces?

When the length of the cord or cable from a busway plug-in device to a suitable tension “take-up” support device does not exceed 6 feet.

# Fill in the blank: For circuits of over \_\_\_\_\_\_\_\_\_ to ground, the electrical continuity of rigid metal conduit (RMC) that contain any conductor other than service conductors are required to be ensured by two lock nuts, one inside and outside of boxes and cabinets.

250 volts

# Fill in the blank: For health care facilities, the ampacity rating requirements for a disconnecting means of diagnostic imaging and treatment equipment, such as x-ray equipment, shall be based on at least \_\_\_\_\_\_\_\_\_ of the input required for the momentary rating of the equipment.

50%

# Fill in the blank: For the purpose of calculating branch-circuits for electric vehicle supply equipment (EVSE), the charging loads shall be considered \_\_\_\_\_\_\_\_\_.

continuous

# Fill in the blank: AFCI protection is required for all 15- and 20-ampere, 120-volt branch circuits supplying outlets located in \_\_\_\_\_\_\_\_\_.

all guest rooms and guest suites of hotels

# Fill in the blank: All swimming pool electric water heaters shall have the heating elements subdivided into loads not exceeding 48 amperes and protected at not over \_\_\_\_\_\_\_\_\_.

60 amperes

# Fill in the blank: In regard to emergency and legally required standby systems, transfer switches shall be \_\_\_\_\_\_\_\_\_, listed, and marked for emergency system or legally required standby use.

automatic

# Fill in the blank: Where Type SE service-entrance cable with ungrounded conductors of sizes 10 AWG or smaller is used for interior wiring as a substitute for Type NM cable is installed in thermal insulation, the ampacity shall be in accordance with the \_\_\_\_\_\_\_\_\_ conductor temperature rating.

60ºC

# Fill in the blank: Power distribution blocks shall be permitted in pull and junction boxes having a volume over \_\_\_\_\_\_\_\_\_ for connections of conductors where installed inboxes, provided the power distribution blocks do not have uninsulated live parts exposed within the box, whether or not the box cover is exposed.

100 cu. in.

# Fill in the blank: Where a receptacle outlet is removed from an underfloor raceway, the conductors supplying the outlet shall be \_\_\_\_\_\_\_\_\_.

removed from the raceway

What is the dimension required by the NEC® for a working space containing live parts on both sides of the equipment that will require examination and maintenance of the equipment when energized and operating at 480-volts between conductors?

4 feet

Where a mobile home park has 25 mobile home lots calculated at 15,000VA each, determine the minimum required ampacity required for the ungrounded service-entrance conductors of the park.

400 amperes

Given: A 3-phase, 150 kVA transformer with a 208Y/120-volt secondary has an existing load of 212 amperes on each of the ungrounded phases.What is the maximum load, in amperes, that may be added to each of the ungrounded secondary phases?

204 amperes

# Fill in the blank: In regard to an isolated grounding type receptacle, the reason the insulated isolated grounding conductor is purposely not bonded to the outlet box is \_\_\_\_\_\_\_\_\_.

for the reduction of electrical noise

# Fill in the blank: As per the Code, no metal parts of ceiling-suspended (paddle) fans in bathrooms are permitted to be located within a zone measured \_\_\_\_\_\_\_\_\_ horizontally from the top of the bathtub rim or shower stall threshold.

3 feet

# Fill in the blank: Type CMP communications cable of not more than \_\_\_\_\_\_\_\_\_ in length shall be permitted in ducts specifically fabricated for environmental air if they are directly associated with the air distribution system.

4 feet

# Fill in the blank: The disconnecting switch or circuit breaker for electric signs and outline lighting systems shall open all \_\_\_\_\_\_\_\_\_ conductors simultaneously on multi-wire branch circuits supplying the sign or outline lighting system.

ungrounded

When an air-conditioning unit is located outdoors on a roof with overcurrent protection of 60 amperes and the disconnecting means is supplied by conductors installed in electrical metallic tubing (EMT) with compression-type fittings, what size wire-type copper equipment grounding conductor, if any, is required to be installed in the EMT?

10 AWG

# Fill in the blank: The grounded conductor of a 3-phase, 3-wire delta service shall have an ampacity of not less than \_\_\_\_\_\_\_\_\_ of the ungrounded conductors.

50%

Given: Four (4) size 2/0 AWG conductors contained in a trade size 2 in.conduit enter a pull box on the “east” side. The conductors then make a U-turn and exit in a trade size 2½ in. conduit on the same side. What is the MINIMUM distance required, in inches, from the “east” side of the pull box to the opposite “west” side of the box?

17 in.

# Fill in the blank: The on-land disconnecting means provided for submersible equipment in a water treatment pond shall not be closer than \_\_\_\_\_\_\_\_\_ from the shoreline.

5 feet

# Fill in the blank: In health care facilities, essential electrical systems shall have a minimum of \_\_\_\_\_\_\_\_\_.

two or more independent sources of power

# Fill in the blank: Lampholders shall be constructed, installed, or equipped with shades or guards so that combustible material is not subjected to temperatures in excess of \_\_\_\_\_\_\_\_\_.

194 degrees F

# Fill in the blank: Pendant conductors having a length of at least \_\_\_\_\_\_\_\_\_ or more, shall be twisted together where not cabled in a listed assembly.

3 feet

# Fill in the blank: For non shielded conductors of over 1000 volts, the conductors shall not be bent to a radius of less than \_\_\_\_\_\_\_\_\_ times the overall conductor material.

eight

# Fill in the blank: At least one structural support member of a building or structure that is direct contact with the earth for at least \_\_\_\_\_\_\_\_\_ or more, with or without concrete encasement shall be permitted to be used as a grounding electrode.

10 feet

# Fill in the blank: The circuit supplying an autotransformer-type dimmer installed in theaters and similar places shall not exceed \_\_\_\_\_\_\_\_\_ between conductors.

150 volts

# Fill in the blank: Given: At least one 125-volt, single-phase 15- or 20-ampere rated receptacle outlet shall be installed within 18 inches of the top of a showwindow of a retail store. No point along the top of the window shall be farther than \_\_\_\_\_\_\_\_\_ from a receptacle outlet.

6 feet

# Fill in the blank: Each luminaire installed in Class III, Divisions 1 and 2 locations shall be clearly marked to show the maximum wattage of the lamps that shall be permitted without exceeding an exposed surface temperature of \_\_\_\_\_\_\_\_\_ under normal conditions of use.

329º F

# Fill in the blank: Conductors supplying a continuous-rated, varying-duty motor shall have an ampacity of not less than \_\_\_\_\_\_\_\_\_ of the motor nameplate current rating.

200%

# Fill in the blank: Where located in Class I, Division 1 locations, transformers containing oilor a liquid that will burn shall be \_\_\_\_\_\_\_\_\_.

installed in vaults only

Where a lighting track is installed with two (2), four (4) ft. sections,mounted end-to-end, how many supports are required?

three

What is the maximum standard size circuit breaker that may be used for overcurrent protection of size 4/0 AWG THWN copper conductors that are not serving a motor load?

250 amperes

# Fill in the blank: According to the NEC®, where a single unit of electric vehicle supply equipment (EVSE) has an ampere rating greater than \_\_\_\_\_\_\_\_\_ or 120-volts,the equipment must be supplied by an individual branch circuit.

16 amperes

# Fill in the blank: The depth of the working space in front of a 120-volt, single-phase, fire alarm control panel (FACP) is required to be at least \_\_\_\_\_\_\_\_\_.

3 feet

What is required when the outer sheath of Type MI cable is made of steel?

A separate equipment grounding conductor must be provided.

What information is not required to be marked on a transformer's nameplate?

overcurrent protection

# Fill in the blank: When combination surface nonmetallic raceways are used for both signaling and for power and lighting circuits, the different systems shall be \_\_\_\_\_\_\_\_\_.

run in separate identified compartments

Where explosion proof equipment is provided with metric threaded entries, which method is approved to adapt the entries from metric threads to NPT threads?

Approved adapters from metric threads to NPT threads shall be used.

# Fill in the blank: Where installed outdoors, dry-type transformers exceeding 112½ kVA shall not be located within \_\_\_\_\_\_\_\_\_ of combustible materials of buildings,unless the transformer has Class 155 insulation systems or higher and completely enclosed except for ventilating openings.

12 in.

A clearance of not less than \_\_\_\_\_\_\_\_\_ must be maintained from the maximum water level of a permanently installed swimming pool and messenger-supported triplex service-drop conductors of 0-750 volts.

22½ feet

Where a residential apartment complex has a total calculated connected lighting load of 205.4 kVA, what is the demand load, in kVA, on the ungrounded service-entrance conductors where applying the standard(general) method of calculation? Given: Each dwelling unit in the complexes cooking facilities provided.

65.3 kVA

For non-dwelling occupancies, the lighting load is permitted to be calculated using an energy code adopted by the local authority when using the values specified in the energy code where: I. the continuous load multiplier of 125 percent is applied. II. the demand factors specified in Table 220.45 are not applied to the general lighting load.

both I and II

One- and two-family dwelling unit services are required to be provided with: I. an emergency service disconnect. II. a surge-protective device.

both I and II

When supplying a 36,000 VA, 240-volt, single-phase load in an area where the ambient temperature reaches 119º F, determine the minimum size75ºC rated copper conductors required to supply the load.

3/0 AWG

# Fill in the blank: Color coding shall be permitted to identify intrinsically safe conductors where they are colored \_\_\_\_\_\_\_\_\_ and where no other conductors of the same color are used.

light blue

What is the minimum bend radius of trade size 4 in. rigid metal conduit(RMC) where the bend is not made with a one-shot or full-shoe bender?

24 in.

Where exceptions are not to be applied, determine the minimum required length of a junction box that has a trade size 3½ in. conduit containing four(4)size 250 kcmil conductors, pulled through the box for a 90º angle pull.

21 in.

# Fill in the blank: An approved method of protection for equipment installed in Class I,Zone 0, hazardous locations is \_\_\_\_\_\_\_\_\_.

encapsulation

# Fill in the blank: Cables operating at over 1000 volts and those operating at 1000 volts or less, are permitted to be installed in a common cable tray without a fixed barrier, where the cables operating at over 1000 volts are \_\_\_\_\_\_\_\_\_.

Type MC

Final Exam 1 Flashcards

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