MIJ
[Four-way switch Symbol]
Four-way switch
[Fuse Symbol]
Fuse
[Ground Symbol]
Ground
What must be done secondary of a transformer?
Ground the secondary
The circuit breaker uses two principal of operation to protect a circuit
Heat and Magnetism.
[Horn Symbol]
Horn
Horsepower
How an electric motor is rated
Insulator:
Impedes the flow of electrons
What effect does inductive reactance have on capacitive reactance?
Inverse Proportionality as inductance increases reactance decreases and visa - versa.
Transformers are rated in
KVA.
KCM
Kilo Circular Mils
When the power factor is other than unity, it may be either
Lagging or Leading.
[Lamp Symbol]
Lamp
What is done to secondary of a transformer including delta secondary?
Must be grounded.
Are thee any limitations in installing a conduit run of 4" galvanized pipe? If so, what are they?
Not more than four 90 degree bends or a total of 360 degree within 100 feet.
An autotransformer has
One winding
A capacitor acts as a(n) _________ (open/closed) circuit for DC.
Open
A capacitor acts as an________ for DC.
Open Circuit
A 2000 watt heater draws 8 amps. What is its rated voltage? Show all work
P = Ex 1 ————— E = P/I = 2000/8= 250 volts
PNP
Positive negative positive — referring to transistors
You are to run conduit to be placed directly against a pl in a wet location, what is acceptable?
rigid non-metallic conduit rigid metallic conduit
Factors to be considered in the section of a voltage system are
size of the building, nature of occupancy, size of load and type of load.
Impedance
the vector sum of the inductive and capacitive reactance, which describes the opposition to the flow of current in AC circuit.
Efficiency of a motor is - efficiency = HP x 746 / Watts x 100
true
In a balanced 3-wire single phase system, the neutral conductor carries _____ percent of the phase conductors.
0
You have a 100v source feeding a 100w lamp, what is the draw?
1 amp
A resistor draws 12 amps and has a resistance of 10 ohms. How much power does it consume?
1,440 Watts (P = 12R)
What is the value of X in the following equation: 45X=120/2 Show each step.
1.33
12/156 is equal to
1/13
A circuit has an operating voltage of 220 volts. The circuit resistance is 55 ohms which limits the current to 4 amperes. You wish to add enough resistance to limit the current to 2 amperes. How much total resistance would you need in this circuit?
110 ohms
It takes ______ 1.5-volt batteries to power an 18-volt load.
12
The phases of a three phase transformer are by _____________ (degrees)
120 degrees.
You receive a delivery of 1500 light fixtures, by the end of the week, only 300 are not installed. You can submit a request for what percentage?
1500 - 300 = 1200, 1200 / 1500 = 0.8 = 80%
A 2000 watts heater draws 8 amps. What is the rate voltage?
250V (E = P//I).
How many current carrying conductors are required for secondary?
3
A 180 volt circuit has a resistance of 4.5 ohms. How much power is consumed? Show our answer in kw.
3.2kw
On a drawing using 4"= 1'. How large will a room that measures 17'6"x 22'?
4 3/8" x 5 " (17'6" = 17.5, 17.5/4= 4.375) ( 22 / 4 = 5.5)
You have a straight conduit run of 3 and 4, what dimensions of the pull box?
4 x 8 = 32 min length [NEC 99 article 370-28P Junction boxes (a) (1)]
You need a pull box for a straight pull in a 4" conduit. How long a pull box is required by code?
4" x 8 = 32"
Use the law of proportionality to solve for the voltage across R1 in the following circuit.
4.8 volts
maximum number of circuit breakers in a panel?
42
A 20-ohm resistor is placed across a 120-volt source of supply. The wattage consumed by the circuit is _______ watts.
720
A rating of one horsepower is equal to________
746 Watts.
One horsepower is equal to_______w.
746 watts
One angle of a right triangle is always a(n)_ degree angle.
90
Manual control
A controller controlled by manual means
Capacitor
A device made with two metal plates and a dielectric between that stores electrons.
Autotransformer
A transformer that uses only one winding for both primary and secondary.
A Commutator converts
A/C to D/C
How does AC differ from DC?
AC changes direction at every half cycle while DC remains constant.
Transformers are cooled by
Air and Oil.
Conductor:
Allows the flow of electrons.
What is meant by a dielectric?
An electric insulator
You would find the dimensions of offices and hallways on the _____________ blue print.
Architectural
The information on a door swing can be found on the_____
Architectural floor/ blue plans/ prints
Additive and subtractive polarities refer to
Batteries and battery connections
What is the definition of eddy current?
Circular induced current contrary to the main currents. Eddy currents are a source of heat power loss in magnetically operated devices.
A 120/208v delta is commonly found where?
Commercial buildings, Schools, Factories
An example of a non-linear load is
Computer or electronic variable speed motor control
What does C.E.M.F. stand for?
Counter Electro Motive Force
A series circuit will have the same ______ at each load.
Current
A series circuit will have the same __________ at each lead.
Current
A capacitor is made up of two conductors separated by a____________.
Dielectric.
The output of a rectifier
Pulsating Direct Current
What is the formula for calculating the resistance of wire?
R = KxL / A
The motor's speed is measured in
RPM - Revolutions Per Minute
Thermal relays will
Remove power to the motor
There is always a ________ angle in a right triangle.
Right
The total resistance of a parallel circuit is always ______ the smallest resistor of the circuit.
Smaller than
[Draw a line diagram of a stop, start station; label all parts.]
Stop Start Station and Parts
The neutral is connected to the__________
Street side of the water main
If a motor control center is located in an electrical equipment room that is otherwise required to be readily accessible means.
The motor control center must not be obstructed. Those that must operate and maintain the equipment must have.
Resistance.
The opposition to current flow
Hertz.
The unit of measurement for the number of cycles per second
Impedance is
The vector sum of inductor, capacitor and resistor, reactances which describe the opposition to the flow of current in an AC circuit.
CEMF
The voltage induced in the armature of a DC motor that opposes the applied voltage and limits armature current.
A variable resistor wired as a potentiometer has _______ leads.
Three
Do not stand on the _______ step of a ladder.
Top
By code, conduit is the smallest size allowable
True
Can a #8 A.W.G. be placed on a 20 amp breaker?
True
The speed of AC machines is easier to adjust than DC machines.
True
The term harmonics has nothing to do with the electrical work.
True
toggle bolts are approved method of anchoring into cinder blocks.
True
A watt meter measures
True Power
To operate a light fixture from five locations, how many 3 Way switches are needed?
Two
To control a light from four locations, it is necessary to install ______ switches.
Two 3-way and two 4-way
True power is represented as watts while apparent power represented as
Volt Amps
In a parallel circuit, the entire ______ is dropped across each load.
Voltage
In a parallel circuit, the entire ___________ is dropped across the load.
Voltage
7. A study of the table of wire insulation is rated in two general areas other than voltage. These are _______ or ____________locations and at not more than a specified_______________
Wet or Dry & Ampacity / Temperature
You are working on a print drawn to a scale of 1/8"-1". A room is 16 feet wide. What would this measure on the print?
X = 2"
Is the neutral conductor the same as the ground conductor?
Yes
Are there any bend limitations in installing a conduit run of 4" galvanized pipe. If so, what are they?
Yes, 360 degrees
The rotating field of a motor is produced by the
armature
Generator
converts mechanical energy into electrical energy.
Magnetic switch control is accomplished by
electromagnetism
Short circuit protection is provided by
fuses and circuit breaker
A motor's output is rated in
horsepower
the energy consumed by a motor is rated in
horsepower
If you reverse direction of current flow through coils of wiring, the direction of the coil will reverse the
magnetic field