181 Final
adjustment, correction
If high ambient temperatures and more than three current-carrying conductors are installed in the same raceway, both ___ and ___ factors must be applied.
unbalanced voltage
____ is the most common cause of motor failure.
temperature rise
____ means the difference between motor winding temperature and the ambient temperature.
panelboards
Feeders are the part of the electrical system that connects the branch circuit ____ to the electrical service equipment.
90
If the selected OCPD has a rating greater than 100 amps, the conductors to be installed shall be selected from either the 75 degrees C or ____ degrees C column of the NEC table 310.15(B)(16).
live
Metal raceways not properly grounded could become ____ and present a shock hazard.
qualified person
The NEC defines ____ as one who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.
derating
The ampacity is the allowable ampacity multiplied by the ___ factor.
blueprints
The construction plans for a building are often called ____.
ampacity
The differences in plugs and receptacles are based on the ___ and voltage rating of the device.
ampacity
The feeder overcurrent protection is sized for the ___ of the feeder conductor.
tungsten
The light-producing element in the incandescent lamp is a ____ wire called the filament.
safety
The reasoning for identifying the system voltages and phase is ____
length
The resistance of a conductor is dependent on the size, material, and _____
hotter than the surface of the sun
The temperatures of an electrical arc, such as might occur on a 480/277 volt solidly grounded, wye connected system, are ____.
true rms
To get accurate current readings where harmonics are involved, ammeters referred to as ____ must be used;
isolated ground
To reduce "electrical noise", circuits with receptacle outlets that serve loads such as cash registers, computers, or other sensitive electronic equipment are often supplied by ___ receptacles.
high dielectric
Today's liquid-filled transformers have their windings immersed in highly refined mineral oil (combustible), silicone fluid, edible seed oil-based dielectric coolant, or other acceptable nontoxic liquids that have ___ properties.
4x4
Trade size ____ square boxes are used primarily to install ceiling outlets
interlocking
Type MC cable is a factory assembly of one or more insulated circuit conductors with or without optical fiber members enclosed in an armor of ___ metal tape, or a smooth or corrugated metallic sheath.
NESC
Utilities make up the connections on the line side and load side of their transformers according to the ____ requirements.
higher the code letter, higher the current
What is the relationship between the Code letter and starting current?
consists of polymer structures which are cured or vulcanized to become natural or synthetic rubber materials.
What is thermoset insulation?
125%
What percentage adjustment is added to a continuous load?
Thermoset
What type of insulation when heated above its rated temperature will char and crack?
90
All working spaces shall allow for the opening of equipment doors and hinged panels to at least a ____ degree.
current and voltage rating
An ac-dc general-use snap switch is always marked with the ____
1 to 2
An acceptable impedance for the grounding path associated with normal equipment grounding for branch circuit wiring is ___ ohms.
30 amps
An appliance is rated at 4500volt-amps, 240v, single phase. What is the maximum size fuse permitted?
luminaires
Flexible metal and nonmetallic conduit are commonly used to connect recessed or lay-in ____. When used in this manner, electricians refer to it as a fixture whip.
dc
Fluorescent lamps can be operated on a ___ circuit if the proper ballasts are used. A ballast for this type of system contains a current limiting resistor that provides and inductive kick to start the lamp.
inverse-time circuit breakers
For motors, the OCPDs are ___
the next higher standard rating may
If the ampacity of a feeder does not match a standard ocpd rating, then ____ be used.
capacitor
In an inductive circuit with an uncorrected power factor of 40 percent to 60 percent, the power factor can be corrected to within 5 percent of unity by the addition of a ____
parabolic reflector
In lamp designations, PAR means ___.
W
Insulated conductors and cables installed in wet conditions must have a ___ designation in their type lettering.
orange
Isolated ground receptacles are required by NEC 406.2(D) to have an ___ triangle on their face.
no
On a 3 phase, 4 wire, wye system, ____ reduction is allowed for nonlinear loads.
35,000
On large electrical installations, an arc flash can generate temperature of ____ degrees F.
125%
When sizing conductors and overcurrent protection, you must take 100% of the noncontinuous loads plus ___ of the continuous loads.
only the larger of any
When sizing feeder conductors, ____ noncoincident loads (loads unlikely to be operated simultaneously such as the air conditioning and the heating) need be included.
6.5
Working space height shall not be less than ___ft.
wattage rating
Lamps are usually selected according to their ____.
number of conductors, cross sectional area, permissable raceway fill.
On what factors do the conduit and tubing size required for an installation depend?
phase
NEC 310.10(H) sets forth the requirements for installing ___ conductors. These requirements are intended to ensure the conductors will share the current equally to prevent overloading individual conductors.
30
NEC 408.36(A) stipulates that if the panelboard contains snap switches with a rating of ___ amps or less, the panelboard overcurrent protection shall not exceed 200 amps.
the box must be big enough for the device so that the conductors aren't damaged when the device is installed.
Of what must you be especially careful regarding the depth of the box you are using?
400
Often the load is such that parallel conductors should be considered. This usually occurs with loads over ___ amps.
longer life, uses less power
How do LED lighting systems compare to incandescent lamps in terms of cost?
overload, insulation failure, bad ventilation, open circuits, unbalanced voltage, short circuits
What are some causes of motor failure?
6
When using a 3 phase supply, the incremental number for determining overcurrent devices is ___ poles.
the contractor
According to the Supplementary General Conditions, who is responsible for any utilities that are damaged?
arc blast
Allowing metal shavings from a drilling operation to fall onto live parts of electrical equipment generally results in an ____, which can cause deadly burns.
90
Although several different types of insulation are listed in the NEC, there are only three different temperature ratings: 60, 75, and ___
ampacity derating
An exception to the ____ rule where two different temperatures are encountered for the same conductors permits the application of the higher ampacity (lower temperature) if the length of the conductors that enter a higher temperature is not more than 10ft or not more than 10% of the total circuit length.
Unilets
Conduit bodies are often referred to in the trade as "condulets" and _____
Starts with a sketch or drawing of the space, symbols are placed, lines are drawn for the circuiting of equipment, then the branch circuits can be assigned.
During the process of laying out an electrical system, when are branch circuits assigned?
horsepower rated
For most applications, the motor circuit switch for a motor must be ___.
Rarely used on lighting circuits, can be used where two separate circuits are to be controlled with one switch, used on gasoline-dispensing pumps, sub pumps etc.
How common are double-pole switches and where are they used?
size, ampacity, ambient temperature rating
Name three issues that must be known when selecting the proper conductor.
anyone
Who may submit a proposal to change the NEC using the Proposal Form found in the back of the NEC?
single-pole
A ____ switch is used where it is desired to control a light or group of lights, or other load, from one switching point.
10
For every ____ degree C rise above the motor's rated temperature, the motor's insulation life is cut in half.
By connecting them to only receptacles and devices that require a neutral conductor, cannot be connected to a switch, run a separate neutral to each device.
How do you prevent neutral conductors from overheating?
86
If the ambient temperature anywhere along the length of a raceway is less than 78 degrees F or higher than ____ degrees F, the ampacity of the conductors in the raceway, or cable, must be modified by a correction factor.
60 degrees F
Raceways or cables exposed to sunlight on rooftops shall be installed a minimum distance of 7/8" above the roof to the bottom of the cable or raceway. Where the distance above the roof to the bottom of the raceway is less than 7/8" a temperature adder of ___ shall be added to the outdoor temperature.
faceplate
The cover that is placed on a recessed box containing a receptacle or a switch is called a ___.
motor location
The reason the code uses the term ___ instead of motor is that, in many instances, the motor is inside an enclosure and is out of sight until an access panel is removed.
W=I(I)xR, H=I(I)xt
What are the formulas for heat generated in a conductor over a long period of time, and for heat generated in a conductor over a short period of time?
eddy current, hysteresis losses
What factors cause losses in ferrous raceways in an ac circuit?
78
What is the metric designator for a raceway of trade size 3?
128 amps
What is the minimum starting current for a 240v, 3 phase, code letter J, 7.5Hp motor?
Ampacity
When considering ____ the temperature on concern is that of the insulation system, not the conductor.
four
When pulling three conductors or cables into a raceway, if the ratio of the raceway diameter to the conductor diameter is between 2.8 and 3.2, jamming can occur. With ___ or more conductors or cables, jamming is highly unlikely.
protection
When referring to motor controllers in the US, we prefer to use the term ___ instead of coordination because coordination has a different meaning.
third harmonic
count the neutral conductor of a 4-wire, 3-phase, wye-connected circuit when the major portion of the load is electric discharge lighting (flourescent, mercury vapor, high-pressure sodium, etc), data processing, and other loads where the neutral conductor carries ____ current.
aluminum
____ wire is seldom used in branch circuits, but because of weight and cost factors, it is frequently selected for feeders and services.
ground faults
_____ occur when an ungrounded conductor comes in contact with a grounded surface or grounded equipment.
mercury vapor
___lamps have the lowest efficacy of the HID family, which ranges from 30 lumens per watt for the smaller-wattage lamps to 65 lumens per watt for the larger-wattage lamps.
125%
NEC 430.24 requires that the conductors supplying several motors, or a motor and other loads, shall have an ampacity not less than _____ of the full-load current rating of the highest rated motor.
copper
NEC table 3.10(B)(18) places the wires available for building construction into two categories: ___ and aluminum.
notice to bidders
Which item in the general clauses and conditions is of value to the contractor and his estimator only?
UL
Which non-profit organization publishes the Electrical Appliances and Utilization Equipment Directory (orange book)?
concrete
Compression fittings for EMT are classified as raintight and ____ -tight types.
yellow
Conductors for 480Y/277 volt systems are generally brown, orange, ____ and gray.
3000
A flourescent lamp with a 30 in its nomenclature indicates it produces light with a color temperature of ___K, which would provide good rendition to warm colors.
hot
An ungrounded condcutor is also known as a ___ conductor.
triplens
Currents of the 3rd harmonic and odd multiples of the 3rd harmonic, add together in the common neutral conductor of a 3 phase system, instead of canceling each other. These odd multiples are referred to as ____
working space
Do not confuse the term ___ with room.
lighter in weight
Dry-type transformers are widely used because they are ___ than comparably rated liquid-filled transformers.
K
For installations where the nonlinear load is huge, most consulting engineers will specify ____-rated transformers.
3
For system voltages of 0 to 150 volts to the ground, the minimum depth of working space is ___ ft.
main feed busbars
In general, panelboards are constructed so the ___ run vertically for nearly the height of the panelboard.
rubber
In general, the letter-type designation R formerly referred to a ___-based covering and now indicates thermoset insulation.
hospital grade
In locations where severe abuse or heavy use is expected, ____ receptacles are recommended.
60
In the U.S., ____ Hz is standard for the fundamental frequency.
OSHA
In the areas where ____ is enforced, the NEC is the law.
Kilo-
In the metric system, what is the prefix for 1000?
120
In three phase motors, each phase is ___ degrees out of phase (symmetrical) with the other phases.
208Y
Most large commercial buildings use two voltages: 480Y/277 volts and ____/120volts.
130
Motors marked with insulation Class B are suitable for use in ambient temperatures of up to ___ degrees C.
arc
NEC 110.16 has a requirement for placing a notice on certain equipment to warn qualified persons of the serious hazard of ___ flash events.
induction heating
Several factors or conditions can cause conductors to overheat, but often overlooked is the possibility of ___.
heating, refrigeration, and air conditioning
The ASHRAE Handbook is considered the Bible of the ___ industry, as the NEC is to the electrical industry.
Insulated
The NEC requires that unless permitted elsewhere in the NEC, all conductors be ____.
open delta
The ____ connection scheme has the advantage of being able to provide either 3 phase or 3 phase and single phase power using only two transformers.
service point
The ____ is defined in NEC article 100 as the point of connection between the facilities of the serving utility and the premises wiring.
Energy Star
The ____ program includes such things as replacing old style magnetic ballasts with high-efficiency appliances with high efficiency appliances.
76 (95x.8)
The allowable ampacity of a 4 awg THHN conductor is 95 amps. If we have four 4awg THHN conductors, what is the adjusted ampacity?
.8
The allowable ampacity of a 4AWG THHN/THWN conductor in a dry location is 96 amps. If four-4AWG current carrying conductors are installed in a raceway, what is the adjustment for this wire?
Amps, ampacity
The maximum current, in ___, that a conductor can carry continuously under conditions of use without exceeding its temperature rating is called ____.
raceway
The term ___ is defined bye the NEC as a channel that is designed and used expressly for the purpose of holding wires, cables, or busbars.
5%
The total voltage drop on a circuit should not exceed what percentage?
low-voltage metering
The two basic methods of metering are primary high-voltage metering and ___.
80
The two most popular types of PVC are Schedule 40 and ____.
Listed
The wording on a counterfeit UL logo might say "approved" instead of ____.
the earth
Throughout this country, and for that matter, throughout the world, ______ is (are) the common reference point for all electrical systems.
linear and nonlinear
To determine reasonable minimum size for a neutral conductor, two types of loads must be considered _____.
cancels out
When all conductors of the same alternating-current circuit are in the same raceway, the magnetic flux around each conductor ___ the magnetic flux of the other circuit conductors.
exposed or concealed locations, if flexibility is required.
When may liquid tight flexible nonmetallic conduit be used?
Ohms
____ Law proves that in a given circuit, the higher the impedance, the lower the current flow.
harmonics
____ are multiplying of a fundamental frequency.
dual-element, time-delay
____ fuses are designed to withstand motor-starting inrush currents and will not open needlessly.
EMT
____ is a thin-wall metal raceway that is not to be threaded.
the color rendering probability
____ is the ability of the lamp to portray objects as normally as possible.
Lumen
____ is the amount of light received in a unit of time on a unit area at a unit distance from a point of source of one candela.
service factor
A motor may be loaded continuously up to the horsepower obtained by multiplying the rated horsepower by the ___.
LFNC-A
Liquidtight flexible nonmetallic conduit marked as ___ has a smooth seamless inner core and cover bonded together and one or more reinforcement layers between the cor and covers for layered conduit.
snap
Most electricians refer to ___ switches as "toggle switches" or "wall switches"
sunlight, ambient temperature, adjacent conductors, current
Name four sources of heat that may damage the insulation of a conductor.
ammeter
Proof of the flux cancellation principle can be demonstrated using a clamp on ____
traveler
A 3-way switch has a common terminal to which the switch blade is always connected, and it has two other terminals called ____ terminals.
gray
When using cable for the wiring of 3 way switches, NEC 200.7(C)(1) permits the use of a conductor with insulation that is white or ___ or has three continuous white stripes (not too common) as a switch supply only if the conductor is permanently reidentified by painting or other effective means.
box adapter
Where PVC conduit is connected to a box or enclosure, a ___ is recommended.
phase-to-ground
GFPE monitors are designed to sense ___ faults only.
incandescent lamps
In the plans for the commercial building, high-efficiency energy saving flourescent lighting and LED lighting is used. Very few ___ are used.
slimline
Instant-start lamps require single pin bases and are generally called ____.
solid-state
LED lighting could be call "___ lighting"
6
NEC 230.71 permits not more than ____ disconnects to serve as the building disconnecting means
spliced
NEC 250.64(C) states that grounding electrode conductors generally shall not be ___
10
NEMA rated motors are designed to operate at plus or minus ____ percent of their nameplate rated voltage.
junction box
Often a feeder serves two or more panelboards, in which case either a ____ or wireway is installed or the feeder connects to the first panelboard and then is extended to the others.
receptacles
GFCI protection can be attained using GFCI circuit breakers or GFCI _____.
EPA
A Toxicity Characteristic Leaching Procedure rating means that the lamp has passed ____ tests regarding the toxicity of the lamp.
room itself
Access to and egress from refer to the actual working space requirements about electrical equipment, not to the ___.
mercury
For a flourescent lamp, the inside of the tube is coated with a phosphor (a flourescing material), the air is evacuated, and an inert gas plus a small quantity of ____ is released into the tube.
panelboard
Separate feeders are to be run from the main service equipment to each of the areas of the commercial building. Each feeders are to be run from the main service equipment to each of the areas of the commercial building. Each feeder will terminate in a ____, which generally will be installed in the area to be served.
load/area
The circuit directory gives the ___ in a wording that would be clear for "nonelectrical" people to decipher and identify the circuit number for lumenaires, receptacles, appliances, or equipment.
impedance
The lower the ___ of the grounding path, the greater the ground-fault current.
Exposure to direct sunlight, adjacent conductors, current flowing, ambient temps can cause ground faults, short circuits, and insulation may soften and melt.
Where would insulation with high-temperature rating be needed and why?
open connections at the transformer, unequal impedance, unequal capacitor banks, single phasing
What are some possible causes of unbalanced voltage?
440.14
What are the rules that govern air-conditioning and refrigerating equipment disconnect means?
each type of
When a box contains fittings such as luminaire studs, clamps, or hickeys, the number of conductors permitted in the box is one less for ____ device.
soft metric conversion
A ____ is when the dimensions of a product already designed and manufactured to the inch-pound system have their dimensions converted to metric dimensions.
green
Color selection for ungrounded "hot" conductors can be just about any solid color except green, white, gray, or any color conductor (except ___) that has three continuous white stripes.
Through 6-32 screws that fasten the faceplate to the grounded yoke. If the box is NM, the yoke must be grounded.
How are snap switches and metal faceplates grounded?
Aluminum tends to corrode over time due to oxidation, u sing an oxidizer preventative can avert that.
How does oxidation affect aluminum conductors, and how can this be averted?
GFCI
In commercial buildings, ____ protection is required for all 125v, single phase, 15 and 20 amp receptacles installed in bathrooms, kitchens, on rooftops, outdoors, within 6ft fromt he outside edge of any sink, in indoor wet locations, in locker rooms with adjacent shower facilities, and in garages, bays, and similar areas.
industrial
Multioutlet branch-circuit ratings are limited to 15-, 20-, 30-, 40-, and 50-ampere except on ____ premises, where they may have a higher rating.
sine
Quality voltage provides a clean ___ wave that free from distortion.
copper, aluminum and aluminum-copper clad
Table 310.14(B)(16) places wires available for building construction into two categories. What are the two categories?
impedance
Voltage drop in a circuit is calculated by multiplying the current flow times the ____.
longer-than-standard length thread cut on one conduit. can be used to connect two enclosures by cutting conduit to length
What is a running thread and how can it be used?
red
When the wiring method is cable, you are stuck with the conductor insulation colors typically provided by the manufacturer. For three conductor cable, this will typically be black, white, and ____.
do not stand in front
When turning a standard disconnect switch on, ____ of the switch.
Any extraneous signal that tends to interfere with the signal normally present in or passing through a system. Can be affected by EMI, RFI, isolating grounding conductors.
What is electrical noise, and what is its source?
