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59. A feeder or service neutral load shall be permitted to have an additional demand factor of __ % applied under certain conditions.

A. 50

B. 60

C. 70

D. 80

Answer: C. 70

It is important to understand the permitted reductions in 220.61 (B) and prohibited reductions in 220.61 (C).

60. Where it is unlikely that two or more noncoincident loads will be in use simultaneously, it shall be permissable to use only the largest load(s) that will be used at one time for calculating the total load of a feeder or service.

A. True.

B. False.

Answer: A. True.

The classic example of noncoincident loads is heating and air conditioning.

61. The optional method for calculating feeder and service loads, given in part IV, applies only to ___

A. dwellings.

B. dwellings and schools.

C. dwellings, schools and new restaurants.

D. farm loads.

Answer: C. dwellings, schools and new restaurants.

It is common practice to figure services based on both Part III and Part IV, and then use the smaller figure.

62. For an outside feeder or branch circuit, 600 volts or less, for spans up to 50', open individual conductors shall not be smaller than ___ AWG copper.

A. 12

B. 10

C. 8

D. 6

Answer: B. 10

This figure is for without a messenger wire. 396.10 covers wiring methods permitted to be messenger supported.

63. Unless supported by messenger wires, overhead conductors for festoon lighting shall not be smaller than ___ AWG.

A. 14

B. 12

C. 10

D. 8

Answer: B. 12

Unlike for overhead spans, a separate value is not specified for aluminum festoon lighting conductors.

64. For festoon lighting spans over ___ feet, a messenger wire is required.

A. 20

B. 30

C. 40

D. 50

Answer: C. 40

Conductors or messenger wires shall not be attached to any fire escape, downspout, or plumbing equipment.

65. The National Electric Code permits multiwire branch circuits for outdoor lighting.

A. True

B. False

Answer: A. True

The ampacity of the neutral conductor shall not be less than the maximum net computed load current between the neutral and all ungrounded conductors connected to any one phase of the circuit.

66. Circuits 120 to 277 volts are permitted to supply outdoor luminaires of industrial establishments, office buildings, schools, stores, and other commercial or public buildings where the luminaires are not less than ___ feet from windows, platforms, fire escapes and the like.

A. 2

B. 3

C. 4

D. 6

Answer: B. 3

277 volts single phase is derived from a three-phase 480Y/277 service.

67. Outside wiring on buildings is permitted to be open wiring on insulators.

A. True

B. False

Answer: A. True

These open conductors must be supported on glass or porcelain knobs, racks, brackets, or strain insulators.

68.Open conductors shall be separated from open conductors of other circuits or systems by not less than ___ inches.

A. 4

B. 6

C. 8

D. 12

Answer: A. 4

Violation of clearances between conductors is a major cause of electric shock.

69. Conductors on poles shall have a separation of not less than ___ inches where not placed on racks or brackets.

A. 6

B. 8

C. 10

D. 12

Answer: D. 12

225.14 (D) gives horizontal climbing space for various conditions.

70. Overhead spans of open conductors and open multiconductor cables of not over 600 volts shall have a clearance of not less than ___ feet above finished grade, sidewalks, or from any platform or projection from which they might be reached where the voltage does not exceed 150 volts to ground and accessible to pedestrians only.

A. 10

B. 12

C. 15

D. 18

Answer: A. 10

For various voltages and types of property, four different clearances are given in 225.18.

71. Where it is unlikely that two or more noncoincident loads will be in use simultaneously, it shall be permissable to use only the largest load(s) that will be used at one time for calculating the total load of a feeder or service.

A. True.

B. False.

Answer: A. True.

The classic example of noncoincident loads is heating and air conditioning.

72. Overhead spans of open conductors and open multiconductor cables shall have a vertical cleaqrance of not less than ___ feet above the roof surface.

A. 4

B. 6

C. 8

D. 10

Answer: C. 8

The vertical clearances above the roof level shall be maintained 3 feet in all directions. There are four exceptions to this rule. Note that a steep roof (over 4"/ft.) has a reduced minimum clearance of 3 feet.

73. From nonbuilding structures, such as tanks, the vertical clearance for overhead conductors shall not be less than ___ feet.

A. 2

B. 3

C. 4

D. 5

Answer: B. 3

This clearance applies to signs, chimneys, antennas and tanks, but not to buildings or bridges.

74. Vegetation such as trees shall not be used for support of overhead conductors except for temporary wiring.

A. True.

B. False.

Answer: B. False.

The exception for temporary wiring was deleted from the 2002 Code. However, outdoor luminaires and associated wiring can be attached to trees. Conductors are run up the tree from an underground line.

75. Except for flexible metal conduit, raceways on exteriors of buildings or other structures shall be arranged to drain and shall be raintight in wet locations.

A. True.

B. False.

Answer: A. True.

Conduit bodies, fittings and boxes used in wet locations must have threaded hubs or other approved means. Threadless couplings and connectors used outdoors or in an indoor wet location must be raintight. With EMT on the outside of a building, use compression fittings.

76.In a multiple occupancy building, each occupant shall have access to the occupant's supply disconnecting means.

A. True.

B. False.

Answer: A. True.

An exception permits authorized management personel to have access to these disconnecting means.

77. The feeder or branch-circuit disconnecting means shall have a rating of not less than the load supplied. In no case shall the rating be lower than ___ amps for a one-family building.

A. 30

B. 60

C. 100

D. None of these

Answer: C. 100

Minimum ratings for disconnects are also specified for-one circuit installations (15 amps),two-circuit installations (30 amps) and all others (60 amps).

78. A building or other structure served shall be supplied by only one service unless permitted in NEC 230.2 (A) through (D). Additional services are permitted to supply, among others, ___.

A. fire pumps.

B. emergency systems.

C. legally required standby systems.

D. All of these

Answer: D. All of these

Additionally, extra services are permitted in special occupancies such as large buildings, and where capacity requirements are in excess of 2000 amps at a supply voltage of 600 volts or less.

79. Where a building or structure is supplied by more than one service, or any combination of circuits, feeders and services, a permanent plaque or directory shall be installed at each service disconnect location denoting all other services, feeders and branch circuits supplying that building or structure and the area served by each.

A. True.

B. False.

Answer: A. True

Such information is crucial to firefighters arriving on the scene. Also maintenance electricians need to know the service layout so that they won't inadvertantly contact energized conductors or equipment.

80. Service conductors supplying a building or other structure shall not pass through the interior of another building or other structure.

A. True.

B. False.

Answer: A. True.

In contrast, feeders and branch circuits can pass through the interior of one building to supply another. This is because feeders and branch circuits have overcurrent protection, and services do not.

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