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Commercial Wiring Final Exam

Terms in this set (136)

Too many devices on one circuit could cause a type of overcurrent known as ______________
overload
A(n) ______________ occurs when there is a low-resistance path between conductors
short circuit
A(n) ___________ is a short between a hot conductor and a grounding path
ground fault
According to the Code, overcurrent protection devices must be ____________
Readily accessible and installed in a closure. Both A and B
Overcurrent protective devices are rated for _____________
amps and volts. Both A and B
The highest fault current an OCPD is designed to handle is the device's ______________ rating
interrupt
The two general types of fuses are plug and ______________
cartridge
A single-element fuse link(s) will melt in response to _________________
overload current
Time-delay fuses allow for___________
momentary overloads
Edison-based fuses are ____________
interchangeable
Circuit breakers can be operated _______________
electrically,manually,pneumatically. All of the above
An inverse-time circuit breaker allows as much as __________ times the overload current before opening the circuit
10
The NEC _____________ rule allows a feeder conductor of smaller ampacity to be tapped without overcurrent protection at the tap.
10-foot tap
All electrical circuits are required to protect against overcurrent.
True
Typically, branch circuit overcurrent devices are located in the power panel.
True
Circuit breakers have to be replaced after they detect an overcurrent
False
The ampere rating of an overcurrent protection device is usually the same as the current-carrying capacity of the circuit conductor
True
The fusible link can be replaced in renewable fuses
True
Cartridge fuses are used in circuits over 120 volts or over 30 amps
True
Single-element fuses are designed for circuits with transient surge currents.
False
Type S fuses must be used on all new installations and for replacement installations.
True
The voltage rating of a fuse should never be lower than the circuit rating
True
Circuit breakers are NOT permitted to serve as a disconnecting switch
False
The conductors extending from the utility pole to the facilities equipment are called the ___________
service
When run overhead, the service is called the __________
service drop
Conductors in a service drop are supported by a _________________
service mast
The minimum vertical clearance of service-drop conductors ranges from ________________
10' to 24.5'
When the service conductors are routed underground, it is called a _________________
service lateral
Service feeders can be directly buried using __________ cable
USE
The smallest service-drop conductor is __________ AWG copper
8
In a service-drop installation, the service conductors are connected to the SE conductors at the _____________
service head
The means of disconnecting all power feeds from the service-entrance conductors can be __________________
The main circuit breaker in the service panel, a fused disconnect switch, a breaker in a service enclosure. All of the above
Electrical service equipment requires a minimum of _______________ clear horizontal space in front of the equipment
30"
Service conductors are always run overhead
False
The minimum vertical clearance of service-drop conductors depends on the service voltage and what is below the conductors
True
Service-drop conductors are NOT allowed to pass over swimming pools.
True
Service conductors run underground are called a service lateral
True
The grounded conductor of a multiconductor cable is permitted to be bare
True
The service head is connected to the meter enclosure
True
A drip loop is an extra 24" to 36" of service-entrance conductors right before the service head
True
Because a service drop is installed high above the ground, the service-entrance conductors DO NOT require insulation
False
The handle of the disconnect switch or main breaker must be mounted no higher than 6'6" above the floor
True
Voltage supply to large industrial plants can be as high as 13,800 V
True
The path from a circuit to earth is called a _____________
ground
When a circuit is connected to earth, it is said to be ________________
grounded
The conductor used to carry noncurrent-carrying metallic parts to the system grounding busbar is a ______________
grounding conductor
The device that establishes an electrical connection to earth is a ______________
grounding electrode
When a conductor contacts grounded metal equipment, the _____________ will trip
overcurrent protection device
The connection of a circuit to the ground is ______________
system grounding
The connection of noncurrent-carrying metal items the the ground is _______________
equipment grounding
The mechanical joining of metallic parts to form an electrically concuctive path is called ______________
bonding
Conductors used for bonding are called _____________
bonding jumpers
The connection between two or more potions of the equipment grounding conductor is a(n) _____________________
equipment bonding jumper
The connection between the grounded circuit conductor and the equipment grounding conductor at the service is a(n) _______________
main bonding jumper
The connection between the grounded circuit conductor and the equipment grounding conductor at a separately derived system is a(n) __________________
system bonding jumper
In system grounding, the grounded conductors are connected to the ___________________
neutral busbar
A grounding electrode conductor is connected between the _____________
grounding busbar and the grounding electrode
The grounded circuit conductor serves to _____________
limit the voltage at which the system operates
The device that is designed to open the circuit when the current-to-ground exceeds 6 milliamperes is a(n) ________________
GFCI
A sensor in a GFCI monitors balance between the ______________ conductors
hot and neutral
AFCI stands for ______________
arc-fault circuit interrupter
The two types of grounding are system grounding and equipment grounding
True
The main bonding jumper may be spliced
False
The bonding jumpers must be the same size or larger than the grounding electrode conductor
True
All circuits require grounding
False
The Code requires any 125 V, 15 or 20 A branch circuit that is NOT GFCI protected to be protected by an AFCI
True
You may use a grounding wedge if you CANNOT use a bonding jumper
True
A neutral busbar is also called a grounding busbar
False
A phase conductor may be used as a grounded circuit conductor
True
Current above 0.006 amps is enough to cause injury
True
An AFCI will detect arcing faults that are NOT detected by standard breakers of GFCIs
True
As a general rule, devices that are double-insulated, guarded, or isolated are exempt from grounding.
True
These conductors extend from the power company terminals to the main service disconnect
Service conductors
These conductors originate at the main distribution panel and terminate at a load center
Feeders
These conductors originate at distribution centers other than the main distribution center and extend to panelboards
Subfeeders
The portion of the wiring system extending past the final overcurrent device is ____________________
branch circuits
Branch circuits are usually _____________ amps or less
30
In hotel rooms, circuits supplying small receptacle loads cannot exceed ___________ volts
120
Mercury-vapor lighting installed 25' high in a warehouse can be supplied by ____________ volts
480,600,240 All of the above
The NEC requires at least one receptacle outlet for every ____________ feet of show-window space, measured horizontally
12
The only externally wired fixtures allowed in a show-window is a(n)
chain-supported fixture
To determine track lighting load requirements, you must know the ____________
total length of track lighting
Sign lighting is considered to be a ____________ load
continuous
Which of the following lighting loads must be calculated using the actual load?
Sidewalk, Security, Parking area All of the above
The minimum number of receptacles required in a commercial installation is _____________
The NEC does not have a minimum requirement
Single, duplex, and triplex receptacles are assigned a load of _____________
180 volt-amps
Multioutlet assemblies require 180 volt-amps for every ______________
5' of length
Appliances and water heaters are noncontinuous loads, which require a load calculation ________________ the electrical equipment
identical to
If there are 3 or more pieces of cooking equipment on a feeder circuit, the load can be ________________
derated
In commercial installation, the heating load is always ______________
100% of the nameplate rating
Subfeeders originate power distribution centers and provide power to _________________
branch-circuit panels
Service conductors extend from the power company terminals to the main service disconnect
True
Feeders are NOT allowed in commercial installations
False
A panelboard can be a single panel or multiple panels
True
The portion of the wiring system extending past the final overcurrent protection device is a branch-circuit
True
An appliance branch circuit supplies a single appliance load
True
A multiwire branch circuit has a grounded conductor for every ungrounded conductor
False
A branch circuit is sized for the load it will supply
True
The smallest general-purpose conductor for branch circuits is 14 AWG
True
Grounded wires from different circuit can be in the same raceway
True
Normally, hot conductors are black, blue, and red
True
A continuous load is a load with a duration longer than 3 hours, such as lighting
True
The general lighting load can be determined by the load per area method, but NOT the actual full-load current of the fixtures
False
The show-window lighting load is considered part of the general lighting load
False
To compute track-lighting load requirements, the total length of track lighting must be known
True
A structure must have at least one circuit exclusively used to supply sign lightning
True
There are some areas of installations, such as hospitals, where the derating factors should NOT be applied
True
The majority of receptacles installed in commercial structures do not supply continuous loads
True
Receptacles that are 15 amps or less do NOT need to be grounded
False
If the number of receptacles is unknown, the receptacle load can be included in the general lighting load
True
If the appliance has a motor, the ampacity of the branch-circuit conductors must be 125% of the current rating of the motor
True
A disconnect for the heater and motor controller is required
True
The disconnect for the heater and motor controller needs to be within sight of the heater
True
When the branch-circuit current rating and the full-load current rating for an air conditioner are on the nameplate, you can use the lesser rating
False
Which element must be present for an explosion to occur?
Oxygen, Explosive substance, Source of ignition All of the above
Areas where a flammable, ignitable, or explosive condition exists during normal operation is a Division ______________ area
1
Areas where a flammable, ignitable, or explosive condition exists under unusual circumstances is a Division ______________ area
2
Class I locations are further identified by the type of ______________
gas present
A flammable liquid having a flash point below 100 degrees F (38 degrees C) is called a _____________ liquid
volatile
The conduit seal must be installed within ___________ feet of the enclosure it isolates
18"
Motors used in Class I, Division 1 areas must be _______________
pressurized with purified air, completely enclosed, explosion-proof All of the above
The enclosures in a Class II area must be __________________
dusttight
Outdoor areas within 20' horizontally and 18" vertically of a(n) _______________ are rated Class I, Division 2
fuel-dispensing pump
Equipment enclosed in a manner that excludes dusts and does NOT permit arcs are _______________
dust-ignition proof
The mounting method for lighting fixtures in hazardous areas is NOT covered by the Class I rating
False
Circuit breakers must be explosion-proof is Class I areas
True
Mineral-insulated cable is allowed in Class I, Division 1 areas
True
Equipment in a Class III location must comply with temperature restrictions
True
The proximity of aircraft play no part when classifying areas within an aircraft hangar
False
Oxygen is required for an explosion to occur
True
Classes define the type of explosive material that is present in an area
True
A motor controller can be the source of electrical arcs
True
Delayed-action plugs are not allowed in Class I areas
False
A seal is placed where a conduit passes from a hazardous to a nonhazardous area
True
An office that is separated from a garage is still considered a hazardous area
False
Dry-type transformers can be used in Class III locations
True
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