Question 1

Wherever such an arrangement is practicable, transformer vaults shall be located so that ____.

Accepted Answer

Transformer vaults should have proper ventilation to the outside air to prevent any buildup of gases and avoid potential dangers. Therefore, reliance on flues or ducts should be avoided. However, the other options of directly placing them under the main service line entrance or adjacent to junction boxes can vary depending on the specific situation and are not a necessary requirement.

Question 2

Barriers are required in all service-entrance motor-control centers to ____ and terminals from the remainder of the motor-control center.

Accepted Answer

Barriers are required in motor-control centers to isolate service busbars and terminals from the remainder of the motor-control center to prevent accidental contact with live parts and ensure safe operation.

Question 3

To calculate the ampacity of conductors supplying several motors (feeder conductors), multiply the largest motor full-load current (FLC) rating by ____% and add the FLC ratings of all other motors (or loads) in the group.

Accepted Answer

To calculate the ampacity of feeder conductors supplying several motors, you multiply the full-load current (FLC) rating of the largest motor by 125% and then add the FLC ratings of all other motors (or loads) in the group. This accounts for the largest motor's starting current, which is higher than its running current.

Question 4

A ____ is the minimum size allowed if the overcurrent protection on the tap conductor's line side is 600 amperes.

Accepted Answer

According to the NEC (National Electrical Code), for a tap conductor with an overcurrent protection device rated at 600 amperes, the minimum size allowed is a 200-ampere rated conductor.

Question 5

____ branch circuits shall be protected at the motor nameplate current rating.

Accepted Answer

Torque motor branch circuits are protected at the motor nameplate current rating, which ensures that the circuit is protected according to the specific current requirements of the motor itself.

Question 6

A 60-ampere rated conductor is the minimum size allowed if the overcurrent protection on the tap conductor's line side is ____.

Accepted Answer

The overcurrent protection on the tap conductor's line side must be at least 125% of the tap conductor's ampacity. Therefore, the overcurrent protection on the tap conductor's line side must be at least 125% of 60 amperes, which is 75 amperes. The only choice that is greater than or equal to 75 amperes is C) 600 amperes.

Question 7

Cable tray systems should be ____.

Accepted Answer

Cable tray systems are expected to be exposed to various weather conditions and environmental elements, hence they should be corrosion-resistant. While it is recommended to mount cable tray systems at least 8 ft. above grade, it is not always necessary, and insulation from frost damage and water tightness are not essential for cable tray systems.

Question 8

If the ungrounded supply conductors are larger than 1100 kcmil copper or 1750 kcmil aluminum, the supply-side bonding jumper shall have an area not less than ____ percent of the area of the largest ungrounded supply conductor or equivalent area for parallel supply conductors.

Accepted Answer

The correct answer is 12.5 percent, as specified in the National Electrical Code (NEC) for determining the size of the supply-side bonding jumper when dealing with large conductors. This requirement ensures proper bonding and grounding for electrical safety.

Question 9

The combined length of one primary plus one secondary conductor (excluding any portion of the primary conductor protected at its ampacity) shall not exceed ____.

Accepted Answer

The answer of The combined length of one primary plus...

Question 10

Where an orderly shutdown is required to minimize the personnel/equipment hazard(s), a system of coordination based on the following two conditions is permitted: (1) coordinated short-circuit protection and (2) ____.

Accepted Answer

Coordinated short-circuit protection is already mentioned in the scenario, so the missing condition should be related to identifying overloads. Option A suggests that overload indication based on monitoring systems or devices can be used to coordinate an orderly shutdown. Using such monitoring systems or devices would help minimize the risk of personnel and equipment hazards. Therefore, option A is the best choice.

Question 11

Cartridge fuse and fuseholder overcurrent protection provisions are located in ____.

Accepted Answer

Cartridge fuse and fuseholder overcurrent protection provisions are located in Section 240.60 through 240.67 of the National Electrical Code (NEC).

Question 12

Overload is defined as operation of equipment in excess of normal, full-load rating, or of a conductor ____ that, when it persists for a sufficient length of time, would cause damage or dangerous overheating.

Accepted Answer

Overload is defined as operation in excess of rated ampacity, which is the current-carrying capacity of a conductor or equipment. Operating at or above the rated ampacity for a prolonged period can cause damage or overheating. Choices A and C provide specific percentages, which may not be relevant to all situations. Choice D mentions peak voltage, which is not directly related to overload.

Question 13

Motor circuits rated 1000 volts, nominal, or less, shall have a disconnecting means with an ampere rating of at least ____% of the motor's full-load current rating.

Accepted Answer

According to the National Electrical Code (NEC), the disconnecting means for motor circuits rated 1000 volts, nominal, or less, must have an ampere rating of at least 115% of the motor's full-load current rating. This requirement ensures that the disconnect can handle the motor's normal operating current plus a margin for occasional overloads without tripping.

Question 14

The tap conductor's ampacity shall not be less than the ____ on the circuits it supplies.

Accepted Answer

The tap conductor's ampacity should be based on the combined calculated loads of the circuits it supplies, which helps ensure that the conductor can safely handle the current demanded by those circuits. In other words, the tap conductor should be able to carry the sum of the currents of the circuits it supplies without exceeding its ampacity rating.

Question 15

A transformer's primary conductors shall have an ampacity at least ____ of the feeder conductors' overcurrent device rating.

Accepted Answer

The answer of A transformer's primary conductors shall have an...

Question 16

Means shall be provided to disconnect all conductors in a building (or other structure) from the ____.

Accepted Answer

The service-entrance conductors are the conductors that bring power into the building from the utility company. Disconnecting these conductors is necessary to completely shut off power to the entire building. The other options (main feeder line, auxiliary panel board, primary panel board) are internal to the building and do not disconnect power from the utility company.

Question 17

If a single raceway supplies an equipment grounding conductor, only one ____ equipment grounding conductor is required.

Accepted Answer

A 3/0 AWG copper conductor is the minimum size required for a single raceway supplying an equipment grounding conductor according to the National Electrical Code (NEC) standards.

Question 18

A transformer vault door must be ____.

Accepted Answer

The transformer vault door must be equipped with fully engaged locks to ensure the safety and security of the transformer within. The other options, while they may also be important features, are not as critical to the functioning of the door as the locks.

Question 19

Knife switches rated more than ____, and at over 1000 amperes at 251 to 1000 volts, shall be used only as isolating switches and shall not be opened under load.

Accepted Answer

Knife switches rated more than 1200 amperes at 250 volts or less, and at over 1000 amperes at 251 to 1000 volts, shall be used only as isolating switches and shall not be opened under load. Therefore, option C is the correct answer.

Question 20

A tap conductor is a ____ that exceeds the value permitted for similar conductors protected as otherwise described in 240.4.

Accepted Answer

According to the definition in the National Electrical Code (NEC), a tap conductor is a conductor that is connected to a feeder or branch circuit to supply load equipment and has a rating or setting that exceeds the value permitted for similar conductors protected as otherwise described in 240.4. In other words, a tap conductor is not protected by overcurrent devices as required for a feeder or a branch circuit. However, if the tap conductor is protected by overcurrent devices ahead of its point of supply, it can be considered a feeder or branch circuit and can be used to supply load equipment. Therefore, Choice A (conductor having overcurrent protection ahead of its point of supply) is the best answer. The other choices are not accurate definitions of a tap conductor.

Quiz 17: Industrial Locations