170 Questions
According to the text, what is the minimum rating for the feeder or branch-circuit disconnecting means in a one-family dwelling?
100 amperes
Where should the emergency disconnecting means be installed for one-and two-family dwelling units?
In a readily accessible outdoor location
What type of surge-protective device (SPD) should be installed if a feeder supplies dwelling units, dormitory units, guest rooms and guest suites of hotels and motels, or areas of nursing homes and limited-care facilities used exclusively as patient sleeping rooms?
Type 2 SPD
Where should the surge-protective device (SPD) be installed in relation to the distribution equipment?
On the load side of the feeder
According to the text, what is the purpose of permanent identification at each supply disconnecting means in a building with multiple sources of supply?
To provide a safety feature for first responders during emergencies
According to the text, what are the requirements for the disconnecting means in a building or structure?
All of the above
According to the text, what are some examples of other means that can be provided for disconnecting the grounded conductor in a building or structure?
None of the above
Which of the following is a requirement for additional services to be permitted?
The AHJ grants special permission
If a building has a calculated load of 2300 amperes, how many services could it have according to the text?
Two 1200-ampere services
In what situations are additional services permitted for lesser loads?
By special permission
What is the maximum number of service disconnecting means that can be grouped in one location according to the text?
Six
According to the text, what is the minimum nominal discharge current rating (In) required for SPDs?
10kA
According to the text, when are multiple services permitted to be installed for a building or structure?
When a single service is not adequate
According to the text, what is the purpose of a permanent plaque or directory at each supply source disconnecting means?
To provide information on the multiple sources of supply
According to the text, what systems or equipment can have additional services supplied to them?
Fire pumps, emergency systems, legally required standby systems, optional standby systems, interconnected electric power production sources, systems designed for connection to multiple sources of supply
Which of the following is NOT an exception to the rule that circuit conductors other than service conductors shall not be installed in the same raceway, cable, handhole enclosure, or underground box as the service conductors?
Feeder or branch-circuit conductors
What is the purpose of using sealant to seal the ends of service raceways?
To prevent water from entering the service equipment
What is the clearance requirement for service conductors installed as open conductors or multiconductor cable without an overall outer jacket?
900 mm (3 ft)
Where must overhead service conductors not be installed?
Beneath openings through which materials may be moved
Which of the following is true about service conductors supplying a building or other structure?
They are only allowed to be installed along the exterior of a building to supply another building
What is the purpose of a permanent plaque or directory in a building or structure supplied by more than one service?
To provide information to first responders, maintenance staff, and other persons who need to disconnect the building or structure from all of its supplies
Under what conditions are service conductors considered to be outside of a building or other structure?
When installed in conduit and under not less than 450 mm (18 in.) of earth beneath a building or other structure
What is the purpose of a second service in a facility with different rate schedules?
To supply a second meter on a different rate
According to the text, what is the minimum size for conductors supplying limited loads of a single branch circuit, such as small polyphase power, controlled water heaters, and similar loads?
12 AWG hard-drawn copper or equivalent
According to the text, what is the minimum vertical clearance required for overhead service conductors above a roof surface?
2.6 m (8 ft 6 in.)
According to the text, what is the maximum voltage between conductors allowed for a reduction in clearance above the overhanging portion of a roof?
300
According to the text, what is the minimum clearance required for overhead service conductors above public streets and roads?
5.5 m (18 ft)
According to the text, what is the maximum length of conductors that pass over a roof allowed for service-mast (through-the-roof) installations located within 4 feet of the edge of the roof?
6 ft
According to the text, what is the minimum clearance required for overhead service conductors above residential property and driveways where the voltage does not exceed 300 volts to ground?
3.7 m (12 ft)
According to the text, what is the clearance required for overhead service conductors at the electrical service entrance to buildings and at the lowest point of the drip loop of the building electrical entrance?
3.0 m (10 ft)
According to the text, what is the minimum ampacity for ungrounded conductors for specific installations?
The rating of the service disconnecting means specified in 230.79(A) through (D)
What is the purpose of a permanent plaque(s) in a building or structure supplied by more than one service?
To identify the multiple supply equipment locations
What is the maximum number of service disconnecting means that can be grouped in one location according to the text?
Six
According to the text, what is the minimum size for service-entrance conductors?
Not less than the largest of 230.42(A)(1) or (A)(2)
According to the text, what raceway types are permitted to be used as a service wiring method for no more than 6 feet?
Liquidtight flexible nonmetallic conduit (LFNC)
According to the text, where is the bonding jumper allowed to be installed when flexible metal conduit or liquidtight flexible metal conduit is used as a service wiring method?
Both inside and outside the raceway
According to the text, which types of cable are permitted to support service-entrance conductors in cable tray systems?
Type IGS cable
According to the text, what is the maximum length allowed for the bonding jumper when installed outside the raceway for flexible metal conduit or liquidtight flexible metal conduit used as a service wiring method?
6 feet
According to the text, what is the minimum size for underground service conductors supplying limited loads of a single branch circuit, such as small polyphase power, controlled water heaters, and similar loads?
12 AWG copper or 10 AWG aluminum or copper-clad aluminum
What are the allowable ampacity options for the grounded conductor in underground service conductors according to the text?
Equal to the minimum size required by 250.24(D)
Which of the following is NOT a wiring method for underground service conductors according to the text?
Type USE conductors or cables
According to the text, what is the purpose of a bonding jumper and listed connector in relation to the grounded overhead service conductor passing over a metal substantial structure?
To provide a bond between the grounded conductor and the substantial structure
According to the text, how many sets of service-entrance conductors are allowed to be supplied by each service drop, set of overhead service conductors, set of underground service conductors, or service lateral?
Only one set
According to the text, when are multiple service disconnecting means permitted in separate enclosures to be grouped at one location?
When they supply separate loads from one service drop, set of overhead service conductors, set of underground service conductors, or service lateral
According to the text, what is the maximum number of service disconnecting means that can be grouped at one location if the number of service disconnect locations exceeds six for any given supply classification?
No maximum limit
According to the text, what is the purpose of providing a plaque or directory at each location of service disconnecting means in a building or structure supplied by multiple services?
To clearly describe all service disconnect locations and branch circuit or feeder supply sources
According to the text, what is the maximum distance between supports for overhead service conductors with a voltage of 1000 volts to ground?
4.5 m
According to the text, what is the minimum clearance required for overhead service conductors above public streets and roads?
150 mm (6 in.)
According to the text, what is the maximum voltage allowed for a reduction in clearance above the overhanging portion of a roof?
150 volts
According to the text, what is the minimum rating required for the service disconnecting means of a one-family dwelling?
100 amperes
According to the text, what is the minimum rating required for the service disconnecting means of all other installations?
60 amperes
According to the text, what is the requirement for the combined ratings of all switches or circuit breakers used in the service disconnecting means?
They must be greater than the rating required by 230.79
According to the text, which of the following equipment is NOT permitted to be connected to the supply side of the service disconnecting means?
Ground-fault protection systems
According to the text, where should service heads and goosenecks be located in relation to the point of attachment of the service-drop or overhead service conductors to the building or other structure?
Above the point of attachment
According to the text, what is the purpose of marking the service conductor with the higher voltage to ground with an orange color or other effective means?
To warn of a potential hazard
According to the text, what is the purpose of barriers in service equipment?
To provide physical separation between load terminals and service busbars
According to the text, what is the purpose of a bonding jumper and listed connector in relation to the grounded overhead service conductor passing over a metal substantial structure?
To ensure continuity of the grounding path
According to the text, what is the maximum number of service disconnecting means permitted for each service allowed by 230.2 or for each set of service-entrance conductors allowed by 230.40, Exception No. 1, 3, 4, or 5?
Six
According to the text, where is the service disconnecting means required to be located when a remote control device(s) is used to actuate it?
Inside the building or structure
According to the text, what is the maximum number of service disconnecting means that can be grouped in one location if the number of service disconnect locations exceeds six for any given supply classification?
Six
According to the text, what are the types of enclosures permitted for the two to six service disconnecting means?
All of the above
Which of the following is a requirement for service equipment to be marked as suitable for use as service equipment?
The equipment must be listed or field evaluated
Where should the surge-protective device (SPD) be located if it is not located at the service equipment?
At each next level distribution equipment downstream toward the load
What is the purpose of the service disconnecting means?
To disconnect all ungrounded conductors in a building or other structure from the service conductors
Where should the service disconnecting means be installed?
At a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors
According to the text, how many service disconnecting means are permitted in a multiple-occupancy building where electric service and electrical maintenance are provided by the building management and under continuous building management supervision?
One
According to the text, what is the minimum rating required for the service disconnecting means in a one-circuit installation?
15 amperes
According to the text, where should the additional service disconnecting means for fire pumps, emergency systems, legally required standby, or optional standby services be installed?
Remote from the normal service disconnecting means
According to the text, what is the purpose of a neutral disconnect link in switchgear or multisection switchboards?
To disconnect the grounded conductor from the premises wiring
According to the text, where should the emergency disconnecting means be installed for one- and two-family dwelling units?
In a readily accessible outdoor location
According to the text, what is the purpose of the emergency disconnecting means for first responders?
To provide a means for utility personnel to safely remove power from a structure
According to the text, what is the minimum short-circuit current rating required for a meter disconnect switch?
Greater than the available short-circuit current at the line terminals
Where should the disconnecting means be marked in a service equipment installation?
On the outside front of the disconnect enclosure with red background and white text
What is the maximum number of circuit breakers or sets of fuses that can be used as the overcurrent device for overload protection in a service equipment installation?
Six
What is the minimum size required for the letters used in the marking of the disconnecting means in a service equipment installation?
13 mm (1.2 in.)
What is the purpose of the service overcurrent device in a service equipment installation?
To provide overload protection for the service conductors
According to the text, what is the maximum ampere rating permitted for rounding up the conductor ampacity to the next standard size circuit breaker or fuse?
800 amperes
According to the text, what is the maximum number of circuit breakers or sets of fuses that can be considered as the overcurrent device in a multiple-occupancy building?
6
According to the text, what is the maximum combined rating of the service disconnecting means OCPDs shown in the exhibit below?
350 amperes
According to the text, what is the maximum voltage allowed for a reduction in clearance above the overhanging portion of a roof?
1000 volts
According to the text, what is the maximum voltage allowed for solidly grounded wye electric services that require ground-fault protection of equipment?
1000 volts phase-to-phase
According to the text, what is the purpose of ground-fault protection of equipment for service disconnecting means?
To provide protection from line-to-ground faults on the load side of the service disconnecting means
According to the text, what is the maximum setting for ground-fault protection system for fault currents equal to or greater than 3000 amperes?
1200 amperes
According to the text, what type of surge-protective device (SPD) should be installed if a feeder supplies areas of nursing homes and limited-care facilities used exclusively as patient sleeping rooms?
Type 1 SPD
According to the text, what is the purpose of ground-fault protective equipment on feeders and branch circuits?
To limit damage to conductors and equipment on the load side in the event of an arcing ground fault on the load side of the protective element
According to the text, where is the bonding jumper allowed to be installed when flexible metal conduit or liquidtight flexible metal conduit is used as a service wiring method?
Outside the raceway
According to the text, what is the purpose of a permanent plaque or directory at each supply source disconnecting means?
To provide information about the supply source
According to the text, what is the purpose of a neutral disconnect link in switchgear or multisection switchboards?
To disconnect the grounded conductor from the grounded service conductor
According to the text, how should positive ungrounded conductors of a dc system be identified if the positive polarity does not serve as the connection point for the grounded conductor?
By an approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black
According to the text, how should negative ungrounded conductors of a dc system be identified if the negative polarity does not serve as the connection point for the grounded conductor?
By an approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red
According to the text, what is the maximum voltage allowed for circuits exceeding 1000 volts ac or 1500 volts dc, nominal, between conductors that supply utilization equipment?
1500 volts dc
According to the text, what is the requirement for branch circuits derived from autotransformers?
They must have a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer
According to the text, what is the minimum ampacity for branch-circuit conductors supplying utilization equipment that will be operated simultaneously?
125 percent of the designed potential load
According to the text, what is the maximum rating required for the overcurrent device in a branch circuit supplying continuous loads or any combination of continuous and noncontinuous loads?
Less than the noncontinuous load
According to the text, what is the maximum number of service disconnecting means permitted in a multiple-occupancy building under continuous building management supervision?
6
According to the text, where are the transformer secondary conductors considered to be service-entrance conductors?
From the service point to the termination in the service equipment
According to the text, where is the service disconnecting means located in the depicted installation?
At the customer-owned transformer primary
According to the text, what are the transformer secondary conductors considered to be between the service point and the service disconnecting means?
Underground service conductors
According to the text, what is the maximum load that an individual branch circuit can supply?
The branch-circuit ampere rating
According to the text, what is the maximum load that a branch circuit supplying two or more outlets or receptacles can supply?
The branch-circuit ampere rating
According to the text, what is the maximum rating of utilization equipment not fastened in place that can be connected to a 15- or 20-ampere branch circuit?
80 percent of the branch-circuit ampere rating
According to the text, what is the maximum rating of utilization equipment fastened in place that can be connected to a branch circuit supplying lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both?
50 percent of the branch-circuit ampere rating
According to the text, what is the minimum clearance required for overhead service conductors above public streets and roads?
4.4 m
According to the text, what is the maximum voltage allowed for circuits exceeding 1000 volts ac or 1500 volts dc, nominal, between conductors that supply utilization equipment?
1000 volts
According to the text, what is the minimum nominal discharge current rating (In) required for SPDs?
5 kA
According to the text, what is the maximum distance between supports for overhead service conductors with a voltage of 1000 volts to ground?
30.0 m
According to the text, what is the purpose of a permanent plaque or directory at each feeder and branch-circuit disconnect location?
To denote all other services, feeders, or branch circuits supplying the building or structure
According to the text, what is the purpose of a neutral disconnect link in switchgear or multisection switchboards?
To disconnect the grounded conductor from the switchgear or multisection switchboards
According to the text, what is the minimum clearance required for overhead service conductors above public streets and roads?
15 feet
According to the text, what is the maximum number of circuit breakers or sets of fuses that can be used as the overcurrent device for overload protection in a service equipment installation?
3
Which of the following is true about feeder conductors over 1000 volts?
They shall be sized in accordance with 235.202(A), (B), or (C)
Which of the following is a requirement for supervised installations?
Conditions of design and installation are provided under engineering supervision and qualified persons with documented training and experience in over 1000-volt systems provide maintenance, monitoring, and servicing of the system
What is the purpose of the equipment grounding conductor in a feeder?
To provide a path for fault current to return to the source
How should ungrounded conductors of a feeder supplied from more than one nominal voltage system be identified?
By separate color coding, marking tape, tagging, or other approved means
According to the text, how should positive ungrounded conductors of a dc system be identified if the positive polarity does not serve as the connection point for the grounded conductor?
Imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B)
According to the text, how should negative ungrounded conductors of a dc system be identified if the negative polarity does not serve as the connection point for the grounded conductor?
Imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B)
According to the text, what is the minimum size for ungrounded conductors for specific installations?
6 AWG copper or 4 AWG aluminum
According to the text, where should outside wiring on surfaces of buildings (or other structures) be installed?
As provided in 305.3
According to the text, what is the minimum size for service-entrance conductors in multiconductor cable?
8 AWG
According to the text, where should an isolating switch with visible break contacts be installed when oil switches or circuit breakers constitute the service disconnecting means?
On the supply side of the disconnecting means
According to the text, what is the maximum ampacity allowed for service-entrance conductors in multiconductor cable?
8 AWG
According to the text, what is the purpose of overcurrent protection for conductors and equipment?
To prevent excessive or dangerous temperature in conductors or conductor insulation
According to the text, which article in the Code provides the general requirements for overcurrent protection and overcurrent protective devices?
Article 240
According to the text, which type of equipment is permitted to be reconditioned?
Low-voltage power circuit breakers
According to the text, which article in the Code covers the protection of conductors?
Article 240
According to the text, where should the service disconnecting means be located for overhead or underground primary distribution systems on private property?
In a location that is not readily accessible
According to the text, what is the requirement for the service disconnecting means in systems rated over 1000 volts?
It must have a fault-closing rating not less than the available fault current
According to the text, what is the purpose of surge arresters in an electrical system?
To provide lightning protection
According to the text, what is the maximum rating for overcurrent devices installed in systems operating at over 1000 volts?
No maximum rating
According to the text, what is the maximum ampere rating permitted for an overcurrent protective device (OCPD) when the ampacity of the conductors being protected does not correspond with the standard ampere rating of the OCPD?
800 amperes
According to the text, what is the maximum ampacity for a 3 AWG copper conductor with a temperature rating of 75°C?
100 amperes
According to the text, what is the maximum ampacity for a 500-kcmil THWN copper conductor?
400 amperes
According to the text, what is the maximum ampere rating permitted for an overcurrent protective device (OCPD) when the conductors it protects have an ampacity of 18 AWG copper?
7 amperes
According to the text, what is the maximum length of run allowed for 15- or 20-ampere circuits using 18 AWG wire?
15 m (50 ft)
According to the text, what is the minimum wire gauge required for 40-ampere circuits?
16 AWG
According to the text, what is the maximum ampere rating for fuses and inverse time circuit breakers shown in Table 240.6(A)?
2000
According to the text, what is the maximum ampere rating for adjustable-trip circuit breakers with external means for adjusting the current setting?
Unlimited
Which one of the following is a certification used to demonstrate that a system has been investigated for cybersecurity vulnerabilities?
All of the above
What is the purpose of a neutral disconnect link in switchgear or multisection switchboards?
To prevent the flow of current in the neutral conductor
What is the maximum voltage allowed for circuits exceeding 1000 volts AC or 1500 volts DC, nominal, between conductors that supply utilization equipment?
1200 volts AC or 1800 volts DC
According to the text, what is the maximum number of circuit breakers or sets of fuses that can be considered as the overcurrent device in a multiple-occupancy building?
8
According to the text, where should the additional service disconnecting means for fire pumps, emergency systems, legally required standby, or optional standby services be installed?
At the location of the fire pump, emergency system, legally required standby, or optional standby equipment
According to the text, where should the surge-protective device (SPD) be located if it is not located at the service equipment?
At the location of the first disconnecting means
According to the text, what is the purpose of a permanent plaque or directory at each feeder and branch-circuit disconnect location?
To indicate the location of the feeder and branch-circuit disconnect
According to the text, what is the maximum number of circuit breakers or sets of fuses that can be used as the overcurrent device for overload protection in a service equipment installation?
Four
According to the text, what is the maximum distance between supports for overhead service conductors with a voltage of 1000 volts to ground?
15 feet
According to the text, what is the maximum ampere rating permitted for an overcurrent protective device (OCPD) when the conductors it protects have an ampacity of 18 AWG copper?
10 amperes
According to the text, what is the minimum clearance required for overhead service conductors above public streets and roads?
10 m (33 ft)
According to the text, what is the maximum load that an individual branch circuit can supply?
30 amperes
According to the text, what is the maximum rating required for the overcurrent device in a branch circuit supplying continuous loads or any combination of continuous and noncontinuous loads?
125% of the continuous load
According to the text, what is the minimum interrupting rating required for branch-circuit overcurrent protective devices?
5000 amperes
According to the text, where should overcurrent protection be provided in a circuit?
In each ungrounded circuit conductor
According to the text, what is the maximum length allowed for branch-circuit tap conductors?
3 m (10 ft)
According to the text, what is the minimum ampacity required for tap conductors supplying equipment with specific instructions on minimum conductor sizing?
As specified in the manufacturer's instructions
According to the text, what is the maximum length allowed for tap conductors in a high bay manufacturing building?
30 m (100 ft)
According to the text, what is the minimum wire gauge required for tap conductors in a high bay manufacturing building?
4 AWG aluminum
According to the text, what is the maximum length allowed for tap conductors located outside of a building or structure?
Unlimited length
According to the text, what is the minimum rating required for the overcurrent device protecting the tap conductors in a high bay manufacturing building?
One-third the rating of the feeder conductors
According to the text, what is the maximum length allowed for the bonding jumper when installed outside the raceway for flexible metal conduit or liquidtight flexible metal conduit used as a service wiring method?
10 feet
According to the text, what is the maximum ampacity for a 500-kcmil THWN copper conductor?
400 amperes
According to the text, what is the maximum voltage allowed for solidly grounded wye electric services that require ground-fault protection of equipment?
600Y/347 volts
According to the text, what are some examples of other means that can be provided for disconnecting the grounded conductor in a building or structure?
Grounding electrode conductor or grounding electrode system
Which of the following is true about coordinated short-circuit protection?
It automatically opens the circuit by localizing and de-energizing the faulted portion of the circuit.
What is the purpose of overload indication based on monitoring systems or devices?
To minimize personnel hazard and equipment damage by facilitating an orderly shutdown.
According to the text, where is ground-fault protection of equipment not required for a solidly grounded wye electrical system?
Installations where ground-fault protection is provided by other requirements for services or feeders.
What is the requirement for an overcurrent device in series with each ungrounded conductor?
A fuse or an overcurrent trip unit of a circuit breaker.
According to the text, what type of circuit breakers are permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads?
Individual single-pole circuit breakers rated 120/240 volts ac with identified handle ties
According to the text, what type of circuit breakers are permitted as the protection for each ungrounded conductor for line-to-line connected loads for single-phase circuits in grounded systems?
Individual single-pole circuit breakers rated 120/240 volts ac with identified handle ties
According to the text, what type of circuit breakers are permitted as the protection for each ungrounded conductor in 4-wire, 3-phase systems or 5-wire, 2-phase systems with a grounded neutral point and a voltage to ground not exceeding 120 volts?
Individual single-pole circuit breakers rated 120/240 volts ac with identified handle ties
According to the text, what type of circuit breakers are permitted as the protection for each ungrounded conductor for line-to-line connected loads for 3-wire, direct-current circuits supplied from a system with a grounded neutral where the voltage to ground does not exceed 125 volts?
Individual single-pole circuit breakers rated 125/250 volts dc with identified handle ties
Test your knowledge on special occupancies and the regulations surrounding additional service equipment. Explore the limitations and permissions for multiple-occupancy buildings.
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