Final Exam 1 for 2020 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

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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 MINIMUM kVA rating.

150 kVA

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Fill in the blank:

Manhole covers shall be OVER ________ or otherwise designed to require the use of tools to open.

75 lbs.

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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

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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 after 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 20 hp, 240-volt, 3-phase, induction type ac motor with a temperature rise of 48 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, a standard cutting die with a ________ taper per ft. shall be used.

¾ in.

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In regard to emergency systems, where internal combustion engines are used as the prime movers, they shall not be solely dependent on a public utility gas system for their fuel supply, unless ________.

it is acceptable to the authority having jurisdiction

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Fill in the blank:

When a motor controller enclosure is installed outdoors and is subject to be exposed to sleet, it shall have a MINIMUM rating of ________, where the controller mechanism is required to be operable when ice covered.

Type 3S

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Each operating room of a healthcare facility shall be provided with a MINIMUM of ________ “hospital grade” receptacles.

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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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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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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.

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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Fill in the blank:

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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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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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 of ________.

16,000 VA

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If a single grounding electrode (rod, pipe, or plate) does not have a resistance to ground of 25 ohms or less, what additional electrode(s) can be used to supplement it?

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

# Fill in the blank: 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

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 at LEAST \_\_\_\_\_\_\_\_

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

# 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 MINIMUM 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

# 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 where given the following conditions? I. The service is 208Y/120 volts, 3-phase, with a 600-ampere rated main circuit breaker. II. 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 required 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, 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.

dusttight

# 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 \_\_\_\_\_\_\_\_.

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

# Fill in the blank: Flexible cord and cables shall be permitted to be attached to building surfaces \_\_\_\_\_\_\_\_.

where 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: In regard to outside branch circuits of overhead spans of open individual conductors for 1000 volts or less up to 50 feet in length, the NEC® mandates the conductors to be not less than \_\_\_\_\_\_\_\_ copper in size.

10 AWG

# Fill in the blank: The ampacity rating requirements for a disconnecting means of x-ray equipment shall be based on at LEAST \_\_\_\_\_\_\_\_ of the input required for the momentary rating of the equipment, if greater than the long-term rating.

50%

# Fill in the blank: As a general rule, the MINIMUM spacing required between live bare metal parts in feeder circuits of 480-volt industrial control panels and bare metal parts of the enclosure is \_\_\_\_\_\_\_\_

1 in.

# 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 \_\_\_\_\_\_\_\_ and approved by the authority having jurisdiction

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 in boxes, 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 MINIMUM 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 15,000 VA each, determine the MINIMUM required ampacity required for the ungrounded service-entrance conductors.

400 amperes

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: Where a central vacuum assembly is located in a storage closet adjacent to the laundry room of a dwelling, accessible non-current-carrying metal parts of the assembly likely to be energized shall be \_\_\_\_\_\_\_\_.

connected to an equipment grounding conductor

# 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

In an industrial establishment, what is the MAXIMUM length of 200 ampere rated busway that may be tapped to a 600 ampere rated busway, without additional overcurrent protection

50 feet

# Fill in the blank: For circuits of OVER \_\_\_\_\_\_\_\_ to ground, the electrical continuity of rigid metal conduit (RMC) or intermediate metal conduit (IMC) that contain any conductor other than service conductors shall be insured with two (2) locknuts, one inside and one outside the box or cabinet.

250 volts

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: When water reaches the height of the established electrical datum plane for an irrigation pond, the adjacent service equipment located on land must \_\_\_\_\_\_\_\_.

disconnect

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

of two 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.

250 volts

# Fill in the blank: 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 show window of a retail store for each \_\_\_\_\_\_\_\_ of show window area measured horizontally.

12 linear ft.

# 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 oil or 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: Motor fuel dispensing systems shall be provided with one or more identified emergency shutoff devices or electrical disconnects. Such devices or disconnects shall not be more than \_\_\_\_\_\_\_\_ from the motor fuel dispensing units that they serve.

100%

# 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

# Fill in the blank: Where an air conditioning unit is supplied with size 6 AWG CU conductors and protected by a 60 ampere circuit breaker, the MINIMUM wire-type size CU equipment grounding conductor permitted for this installation is \_\_\_\_\_\_\_\_.

10 AWG

What is not required to be marked on the nameplate of a transformer?

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

What is an approved method to adapt explosion proof equipment with metric threaded entries 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.

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

22 ½ feet

Where an apartment complex has a 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 complex has cooking facilities provided.

10 feet

What is the MINIMUM permitted sill or curb height of a transformer vault doorway?

4 in.

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 size 75ºC 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

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