139 Questions
Which of the following is true about the location of overcurrent protective devices?
They should not be exposed to physical damage
Where are overcurrent protective devices not allowed to be located?
In bathrooms
What is the correct position for mounting enclosures for overcurrent devices?
Vertical position
What is the purpose of a disconnecting means for fuses?
To independently disconnect each circuit containing fuses
Which type of plug fuse is identified by a hexagonal configuration of the window, cap, or other prominent part?
Type S fuse
What is the maximum voltage for plug fuses in circuits supplied by a system with a grounded neutral point?
150 volts
Which type of fuse is designed to prevent installation of a fuse exceeding the ampacity of the conductor being protected?
Type S fuse
What is the maximum voltage for cartridge fuses and fuseholders of the 300-volt type?
300 volts
According to the text, what information must be marked on fuses used for supplementary protection?
Ampere rating and current limiting
According to the text, what types of cartridge fuses must be marked with the interrupting capacity (IC) rating?
Class G, J, K, L, R, and T
According to the text, what is the maximum clearing time a fuse should have at the available arcing current?
0.07 seconds
According to the text, what is one of the means provided to reduce clearing time in an arc energy reduction system?
Energy-reducing maintenance switching with local status indicator
Which type of circuit breaker should be used on a 480-volt system with up to 480 volts to ground, derived from a corner-grounded, delta-connected system?
A circuit breaker marked 480 volts
Which type of circuit breaker is not intended for use on a delta-connected 240-volt circuit?
A circuit breaker marked 120/240 volts
Which type of circuit breaker should be used on a system that requires a 240-volt, 480-volt, or 600-volt circuit breaker?
A circuit breaker marked 600 volts
Which one of the following conditions must be met when the secondary conductors of a transformer are located outside of a building or structure, except at the point of load termination?
The conductors must be protected from physical damage in an approved manner.
Which one of the following statements is true regarding the overcurrent protection for secondary conductors installed in accordance with 240.21(B)(3)?
The overcurrent protection must be provided by a single circuit breaker or a single set of fuses that limit the load to the ampacity of the conductors.
Which one of the following statements is true regarding secondary conductors that are not over 7.5 m (25 ft) long?
The secondary conductors must have overcurrent protection as specified in 240.21(B)(3).
Which of the following is true about circuit breakers used as switches in high-intensity discharge (HID) lighting circuits?
They have undergone additional endurance and temperature testing
According to the text, what is the purpose of marking the ampere rating on circuit breakers?
To ensure durability and visibility after installation
Which of the following is true about the position of circuit breaker handles when operated vertically?
The 'up' position is the 'on' position
According to the text, what is required for a circuit breaker's trip point or operation time to be altered?
Both dismantling of the device and breaking of a seal
Which of the following statements is true about the secondary conductors of a transformer?
The secondary conductors must have an ampacity that is not less than the value of the primary-to-secondary voltage ratio multiplied by one-third of the rating of the overcurrent device protecting the primary of the transformer.
Which of the following is NOT a permitted method of protecting service conductors?
Overcurrent devices in accordance with 445.13.
In what locations are overcurrent devices required to be readily accessible?
Next to the appliance, motor, or other equipment they supply and reachable by using a ladder.
Under what conditions can an overcurrent device be connected in series with a grounded conductor?
When the overcurrent device opens all conductors of the circuit, including the grounded conductor, and is designed so that no pole can operate independently.
Which of the following is true about series-rated systems?
Series-rated systems consist of circuit breakers that protect circuit breakers.
What is required for a series-rated system to be applied in any new or existing installation?
The arrangement of protective components must be as specified in 240.86(B) for tested combinations applied to existing installations.
Who should select the series rated combination devices for existing installations?
A licensed professional engineer engaged primarily in the design or maintenance of electrical installations.
Which part of the Code covers surge-protective devices (SPDs) permanently installed on premises wiring systems of not more than 1000 volts, nominal?
Part II
What is the voltage rating that distinguishes surge-protective devices (SPDs) covered by Part II and those covered by Part III?
1000 volts, nominal
Which type of surge-protective device (SPD) is permitted to be connected on the supply side of the service or building disconnecting means?
Type 1 SPD
Which of the following is a permitted method of achieving arc energy reduction in a circuit breaker?
Increasing the instantaneous trip setting
What determines whether additional arc energy reduction techniques are required in a circuit breaker?
The final setting of the instantaneous trip
What is the purpose of the energy-reducing maintenance switch in a circuit breaker?
To override the instantaneous trip setting
Which type of circuit breaker setting adjustment can help reduce incident energy in an arc-flash event?
Adjusting the instantaneous trip setting
Which of the following methods can be used to reduce clearing time in an arc energy reduction system?
All of the above
Which of the following is NOT a permitted method of reducing clearing time in an arc energy reduction system?
Energy-reducing maintenance switching
Which of the following statements is true about circuit breakers without the capability of an instantaneous response?
They have a longer protective device opening time
Which of the following is true about the continuous current trip setting for an arc energy reduction system?
It is the rating of the installed circuit breaker or trip plug
Which of the following is true about the ampacity of conductors protected by overcurrent devices rated over 800 amperes?
The ampacity of the conductors must be greater than 95 percent of the rating of the overcurrent device.
Which of the following is true about the protection of conductors in supervised industrial installations?
Conductors must be protected in accordance with 240.91(A) or 240.91(B).
Which of the following is true about the sizing of feeder taps in accordance with Table 240.92(B)?
Feeder taps can be sized based on the short-circuit temperature limit of the tap conductors.
Which of the following is true about the location of overcurrent devices in ungrounded circuit conductors?
Overcurrent devices must be connected at the point the conductors receive their supply.
Which one of the following is true about series-rated systems?
Series-rated systems eliminate the need for a wholesale replacement of electrical distribution equipment.
According to the text, what is required for a series-rated system to be applied in any new or existing installation?
The existing circuit breakers must be compatible with the newly installed upstream protective device.
Which of the following is true about the location of overcurrent protective devices?
Overcurrent protective devices must be located in readily accessible locations.
According to the text, what determines whether additional arc energy reduction techniques are required in a circuit breaker?
The clearing time of the circuit breaker
Which of the following conditions must be met to protect the conductors from short-circuit and ground-fault conditions when the length of the secondary conductors does not exceed 30 m (100 ft)?
The transformer primary overcurrent device has a rating or setting that does not exceed 150 percent of the value determined by multiplying the secondary conductor ampacity by the secondary-to-primary transformer voltage ratio.
Which of the following is a permitted method of protecting the conductors against overload conditions?
The sum of the overcurrent devices at the conductor termination limits the load to the conductor ampacity.
Which of the following is true about the protection of conductors in supervised industrial installations?
The conductors must be considered to be protected if calculations, made under engineering supervision, determine that the system overcurrent devices will protect the conductors within recognized time vs. current limits for all short-circuit and ground-fault conditions.
Which of the following is true about the protection of conductors in outside feeder taps?
The conductors must be permitted to be tapped to a feeder or to be connected at a transformer secondary, without overcurrent protection at the tap or connection, as long as certain conditions are met.
Which article in the text covers elevators, dumbwaiters, escalators, moving walks, platform lifts, and stairway chairlifts?
Article 620
What is the maximum voltage for outdoor overhead conductors covered in the text?
395 volts
According to the text, what does UL 1449 cover?
Surge Protective Devices (SPDs) with Types 1, 2, 3, and 4
Which of the following is true about series-rated systems?
They eliminate the need for wholesale replacement of electrical distribution equipment.
What is the purpose of an engineered series-rated system?
To provide upstream protection that functions in concert with the existing protective devices to safely open the circuit under fault conditions.
Which circuit breakers are most likely to be compatible with series-rated systems?
Those that will remain closed during the interruption period of the fully rated OCPD installed on their line side.
What must be considered when designing a series-rated system?
The fault-clearing characteristics of the existing protective devices and their ability to interact with the newly installed upstream protective device(s) under fault conditions.
Which type of surge-protective device (SPD) must be installed in listed equipment where the SPD is provided with a disconnecting means and overcurrent protection?
Type 2 SPDs
What is the maximum voltage for plug fuses in circuits supplied by a system with a grounded neutral point?
240 volts
What is the maximum clearing time a fuse should have at the available arcing current?
3 seconds
What is the purpose of the energy-reducing maintenance switch in a circuit breaker?
To provide a means for maintenance personnel to safely work on the circuit
Which of the following is true about the location of surge arresters?
Surge arresters must be listed for installation in accessible locations.
What is the minimum size for the conductor between the surge arrester and the line, and the surge arrester and the grounding connection?
6 AWG copper or aluminum
How is the magnitude of the reflected wave affected by the distance between the surge arrester and the protected equipment?
The magnitude of the reflected wave increases as the distance from the arrester increases.
How can a surge arrester be connected to a transformer that supplies a secondary distribution system?
Through a metal interconnection to the secondary grounded circuit conductor.
According to the text, what is the purpose of grounding in electrical systems?
To limit the voltages caused by lightning or by accidental contact of the supply conductors with conductors of higher voltage
According to the text, what is the performance objective for the effective ground-fault current path in high-impedance grounded systems?
To ensure operation of the required ground detector to indicate the existence of a ground-fault condition
According to the text, what is the purpose of bonding electrical equipment?
To create a low-impedance path for ground-fault current
According to the text, where should non-current-carrying conductive materials enclosing electrical conductors or equipment be connected to?
Supply system grounded equipment
Which type of surge-protective device (SPD) is permitted to be connected on the load side of a branch-circuit overcurrent protection device up to the equipment served?
Type 3 SPD
Where can Type 2 surge-protective devices (SPDs) be connected in a feeder-supplied building or structure?
Anywhere on the load side of the first overcurrent device
Which type of surge-protective device (SPD) must be installed on the load side of the service-disconnect overcurrent protection device, unless installed in accordance with a specific code section?
Type 2 SPD
Where can Type 1 surge-protective devices (SPDs) be connected in a service-supplied building or structure?
Anywhere on the line side of the first overcurrent device
Which of the following is true about the requirements for grounding and bonding of electrical systems?
The requirements for grounding and bonding are provided in Article 250, Parts III and X.
What is the purpose of connecting non-current-carrying conductive materials to earth in electrical equipment?
To limit the voltage to ground on these materials.
Which of the following is NOT a requirement for grounding and bonding of electrical systems?
Limiting the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines.
What is the purpose of Article 250 in the text?
To cover general requirements for grounding and bonding of electrical installations.
Which of the following is true about the grounding of the system in the service disconnecting means enclosure?
The grounded conductor is intentionally connected to a grounding electrode via the grounding electrode conductor (GEC).
What is the purpose of bonding the equipment grounding bus to the grounded or neutral bus within the service disconnecting means enclosure?
To provide a ground reference for exposed non-current-carrying parts of the electrical system.
Where does the circuit for ground-fault current through the grounded service conductor back to the utility transformer originate from?
The grounding electrode via the grounding electrode conductor (GEC).
Which one of the following is true regarding the protection of conductors against short-circuit and ground-fault conditions?
The length of the secondary conductors must not exceed 30 m (100 ft) and the transformer primary overcurrent device must have a rating or setting that does not exceed 150 percent of the value determined by multiplying the secondary conductor ampacity by the secondary-to-primary transformer voltage ratio.
Which one of the following is true regarding the protection of conductors against overload conditions?
The sum of the overcurrent devices at the conductor termination limits the load to the conductor ampacity.
Which one of the following is true regarding the physical protection of secondary conductors?
The secondary conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
Under what conditions are outside feeder taps permitted without overcurrent protection at the tap or connection?
All of the above.
Which of the following is true about the purpose of grounding and bonding in electrical systems?
Grounding and bonding are necessary to prevent objectionable current.
What type of alteration is permitted if multiple grounding or bonding connections result in objectionable current?
Interrupting the continuity of the conductor or conductive path causing the objectionable current.
What potential differences can develop between ground and the neutral of electronic equipment?
All of the above.
Which one of the following is true about the sizing of grounding electrode conductors in an impedance grounded system?
The sizing is based on the ampacity of the service conductors.
What is the purpose of the grounding electrode conductor in an electrical system?
All of the above.
Which one of the following is true about the sizing of the grounding electrode conductor?
The sizing is based on the ampacity of the service conductors.
Which of the following is true about the grounding requirements for alternating-current systems of less than 50 volts?
All of the above
Which of the following is true about the grounding requirements for alternating-current systems of 50 volts to 1000 volts?
All of the above
Which of the following is true about the grounding requirements for alternating-current systems of over 1000 volts?
They must be grounded if supplying other than mobile or portable equipment
What is the purpose of grounding a 3-phase, 4-wire, wye-connected system?
To enable line-to-neutral loads to be supplied
Which of the following ac systems of 50 volts to 1000 volts shall be permitted to be grounded but shall not be required to be grounded, according to the text?
Other systems that are not required to be grounded in accordance with 250.20(B)
Which of the following is NOT a condition that must be met for separately derived systems supplied by transformers that have a primary voltage rating of 1000 volts or less to be permitted to be grounded but not required to be grounded, according to the text?
The system is used exclusively for supplying power to adjustable-speed industrial drives.
Which of the following systems are examples of common electrical distribution systems that are permitted but are not required to have a circuit conductor that is intentionally grounded, according to the text?
Delta-connected, 3-phase, 3-wire, 480-volt systems
Why are ungrounded electrical systems operated in some limited applications, according to the text?
To ensure continuity of operation
Which of the following is NOT a recommended solution for isolating electronic equipment from power equipment ground?
Grounding the electronic equipment to an isolated earth ground
Under what conditions can an overcurrent device be connected in series with a grounded conductor?
When the overcurrent device is rated for less than the full load of the grounded conductor
Which of the following is true about the connection of grounding and bonding equipment?
Machine screw-type fasteners must engage not less than two threads
According to the text, what is the purpose of connecting non-current-carrying conductive materials to earth in electrical equipment?
To provide a low-impedance ground-fault return path
Which of the following is true about the sizing of grounded conductors in parallel in two or more raceways or cables?
The size of each grounded conductor(s) in each raceway or cable shall not be smaller than 1/0 AWG and shall be sized in accordance with 250.24(D)(2)(a) or (D)(2)(b) in accordance with 250.24(D)(1).
Which one of the following is true regarding the grounding of a 3-phase, 3-wire delta service?
The grounded conductor of a 3-phase, 3-wire delta service shall have an ampacity not less than that of the ungrounded conductors.
Which one of the following is true about the location of the grounded conductor in an ac system operating at 1000 volts or less?
The grounded conductor(s) shall be routed with the ungrounded conductors to each service disconnecting means and shall be connected to each disconnecting means grounded conductor(s) terminal or bus.
What is required for a circuit breaker's trip point or operation time to be altered?
A circuit breaker's trip point or operation time can be altered by adjusting the instantaneous trip setting.
Which of the following is true about the grounding requirements for an AC service supplied by a grounded ac service?
The grounding electrode conductor connection must be made at the service disconnecting means.
Which of the following is a permitted location for the grounding electrode conductor connection?
At the terminal or bus to which the grounded service conductor is connected
Which of the following is true about the grounding requirements for outdoor installations?
Outdoor installations help mitigate the effects of lightning and accidental crossovers.
Which of the following is true about the grounding requirements for dual-fed services?
A single grounding electrode conductor connection is required for each power source.
According to the text, where should the grounding electrode conductor connection be made in a premises wiring system supplied by a grounded ac service?
At any accessible point from the load end of the overhead service conductors
According to the text, where should at least one additional grounding connection be made if the transformer supplying the service is located outside the building?
At the transformer
According to the text, in a dual-fed service with a common enclosure or separate enclosures and employing a secondary tie, where should the grounding electrode conductor connection be made?
At the tie point of the grounded conductor(s) from each power source
According to the text, where should a grounded conductor not be connected on the load side of the service disconnecting means?
To normally non-current-carrying metal parts of equipment
Which of the following systems can make supply-side connections and operate in parallel with the utility service?
Photovoltaic systems
What is the primary function of the main bonding jumper and the system bonding jumper in a grounded system?
To create the link for ground-fault current between the EGCs and the grounded conductor
Which of the following materials can be used for main bonding jumpers and system bonding jumpers?
Copper
How should a main bonding jumper or a system bonding jumper be identified if it is a screw only?
With a green finish that is visible with the screw installed
Which one of the following is true about the sizing of the main bonding jumper for a service with more than one enclosure?
The main bonding jumper size is determined by the size of the largest phase conductor or phase conductor set.
What is the purpose of the system bonding jumper in a separately derived system with more than one enclosure?
To prevent parallel neutral current paths on raceways and enclosures.
Which one of the following is true about the connection of grounding and bonding equipment?
Grounding and bonding equipment must be connected in accordance with the manufacturer's instructions.
What is required for a circuit breaker's trip point or operation time to be altered?
The circuit breaker must be equipped with an adjustable trip setting.
Which of the following is true about the sizing of system bonding jumpers for paralleled installations?
The sizing is based on the busbar ampere rating per ungrounded phase
When should a supply-side bonding jumper be installed in a separately derived system?
When the source and the first disconnecting means are located in separate enclosures
What type of supply-side bonding jumper is required to comply with 250.102(C)?
Wire type
What is the minimum size requirement for the grounded conductor(s) in raceways or cables when the ungrounded conductors are connected in parallel?
Not smaller than 1/0 AWG
Which one of the following is true about the grounding requirements for systems connected on the supply side of the service disconnect and installed in separate enclosures from the service equipment enclosure?
The grounding of both grounded and ungrounded systems shall comply with 250.24(A) through (D)
Which one of the following is true about the grounding of systems connected on the supply side of the service disconnect and installed in separate enclosures from the service equipment enclosure?
The grounding of both grounded and ungrounded systems shall comply with 250.25(B)
Which one of the following is true about the grounding of systems supplied by an ungrounded ac service?
The grounding electrode conductor shall be connected to a metal enclosure of the service conductors
Which of the following is true about the sizing of the grounding electrode conductor?
The sizing of the grounding electrode conductor is based on a comparison between 220.61 and 250.102(C)
Under what conditions can an overcurrent device be connected in series with a grounded conductor?
An overcurrent device can be connected in series with a grounded conductor if the source of the separately derived system is located within equipment listed and identified as suitable for use as service equipment
Which of the following is true about the grounding requirements for outdoor installations?
The grounding requirements for outdoor installations are the same as for indoor installations
Which of the following is true about the location of overcurrent protective devices in ungrounded circuit conductors?
Overcurrent protective devices must be located at the point where the ungrounded circuit conductor originates
According to the text, where should the system bonding jumper be installed in a separately derived system that has no disconnecting means or overcurrent devices?
At the source of the separately derived system
According to the text, where should the system bonding jumper be installed if the source of a separately derived system is located outside the building or structure supplied?
At the grounding electrode connection
According to the text, what is the exception for the sizing of the system bonding jumper for a system that supplies a Class 1, Class 2, or Class 3 circuit, and is derived from a transformer rated not more than 1000 volt-amperes?
The system bonding jumper shall not be smaller than the derived ungrounded conductors
According to the text, where should the system bonding jumper be installed in a dual-fed service with a common enclosure or separate enclosures and employing a secondary tie?
At the paralleling switchgear, switchboard, or other paralleling connection point
Test your knowledge of circuit breaker operations and indications with this quiz. Learn about the requirements for manual and non-manual methods of operation, as well as the importance of clear indications for the open and closed positions.
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