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144 Cards in this Set

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What is the recommended color coating of a WYE connected, low voltage system?
Black, Red, Blue
What is the recommended color coating of phases A, B and C on a WYE connected 480V system?
Brown, Orange, Yellow
When a wiring system is labeled 240V, what kind of voltage is that considered to be?
effective voltage
When planning out a concentric bend, what part of the bend do you measure?
The inside of the bend (plus add a distance for stand off and 1/2 the outer diameter of the pipe) so the answer may more correctly be to the center of the pipe
What measurement is taken when planning an offset bend?
bottom to bottom of the pipe
When trying to preserve a wooden ladder, what should never be done?
do not paint the ladder
Watts are ------ proportional to resistance.
inversely
List the three power equations ohms law
P = I *E
P = R * I(2)
P = E(2)/R
List the 3 ohms law formulas for Resistance.
R = E/I
R = E(2)/P
R = P/I(2)
Can you add in series/paralled circuit the power dissipated in each resistor to get the total power draw in the circuit?
Yes. (Add all power from the series and parallel components to get the total power draw of the circuit)
To convert a decimal into a fraction you must -----
take the number (.25 for example) and divide it by the decimal value (25/100) then simplify (1/4)
When adding or subtracting fractions, you must come up with -----
a common denominator, then add accordingly
When multiplying or dividing fractions you must ----
multiply straight across, when you divide, flip one fraction.
What is required on a scaffold?
a toe board
What do you use a jog switch for?
bumping the motor
An Ohmmeter measures -----
continuity and resistance
Electric drill motors are rated by ------
chuck size
If you run a 3 phase circuit in different conduits, it will cause -----
excessive heating
If 4, 5 and 6 motor leads are tied together in a Wye system, it is ------
low voltage
To change the direction a motor is running, you must ------
exchange any 2 leads of the motor stator
In a 3 phase AC generator there are ----- output voltages that are ------ degrees out of phase
3
120
Transformer current losses are reduced by -----
laminating the core
What type of transformer has some coils that are shared with the primary and secondary?
Autotransformer
What advantage does DC power have over AC power?
speed control
What is the most important factor for sizing wire?
current
What is the load on the neutral conductor if both hot conductors are carrying 15 amps?
zero (load is balanced)
How does a battery carry power?
with chemical action (electro-chemical)
3 and 4 way switches are installed so that the switching is done with ----
the ungrounded conductor
J boxes must be ------
readily accessible???? I think just accessible
2000W load at 115 volts, what size circuit needs to be run?
2000/115= 17.39
You need a 20 A circuit
#14 AWG wire can safely carry 15 amps on a 120V circuit. How many amps can be carried on a 480V circuit?
The same. 15 amps
The NEC is enforced by the -----
Building department
Type S fuses are -----
tamperproof
The neutral feeder must be large enough to -----
carry the maximum unbalanced load
Conductors sized ------ must be stranded
#8 AWG and larger
A Grounding Electrode must be protected by conduit when -----
it is smaller than #6 AWG
Rebar used as an electrode should not be shorter than -----
20 feet
The minimum general lighting load of a dwelling shall be calculated at -----
3 VA/sq foot
Always mount a knife switch -----
with the hinge at the bottom (so that when the knife switch is closed it is in the "up" position)
A triangle is the symbol for a ------
Delta connection
In an ------ not all parts of the circuit are in contact.
open circuit
The rating of one portable appliance shall not exceed ----- of the branch circuit.
80%
A watt meter is hooked up in -----
both series and parallel (2 current coils hooked up in series, and 1 potential coil hooked up in parallel)
A capacitor ------ energy.
stores
An overcurrent trip unit is hooked up in ------ with each ungrounded conductor.
series
If current increases, the magnetic field -----
increases
On a binding post, wrap the conductor in the ------- the nut tightens.
same way (direction)
3 way switching does not use the ------ conductor.
grounded
In motor circuits, a stop switch is wired in ------, while a start switch is wired in ------.
series
parallel
A universal motor has brushes that ride on a -----
commutator
Discoloring on one end of a fuse usually means -----
bad contact
On a balanced 3 wire circuit the neutral carrys ----- load.
zero
To make a resistance measurement, power must be -----
off
A ----- impedes or opposes current.
insulator
Rigid steel is usually ----- to prevent corrossion.
enamored
A ----- operates by temperature changes.
thermostat
What is the best way to lay out a straight line?
Use a chalk line
What should be used to attach items on a hollow wall?
toggle bolts
DPDT identifies a ------
switch
A burned out fuse that can be easily replaced is a -----
renewable fuse
A ----- is a tool that is used to cut internal threads.
tap
the main objective to grounding conduit is to -----
prevent energizing metal parts above ground potential.
A ground electrode must be protected by conduit when smaller than -----
4 AWG (or 6AWG, if special circumstances are met)
When resistance goes up, amperage goes -----
down
When using an ammeter to measure current in a circuit, it must be in ------
series
A cartrige is rated for ------
current and voltage
A remote circuit is a ------
3 wire circuit
The output of a generator is measured in -----
watts
Define volt.
The unit of voltage
If the coil of a magnetic relay chatters, it is -----
defective
What is a megger?
An ohm measuring tool
How many watts in a horsepower?
746
The output of a transformer aka ------, is marked with an -----
secondary
X
----- are used with half wave and full wave rectifiers.
Diodes
The winding connected to the source voltage is ------
primary
When installing an electrical system according to blue prints, what takes presidence?
Specifications
When you desire higher voltage, connections should be made in -----
series
When ordering a hacksaw blade, order according to ------
length and teeth per inch
Contactors and motor starters are similiar except -----
a contactor has no overload protection
If power is applied to a control circuit and there is no power, what is the likely cause?
The holding contacts are not holding
When bending rigid pipe, use a -----
hickey
3 phase power source has ------ between phases.
120 degrees
What is the easiest way to reduce voltage drop?
Increase the wire size
What type of meter is a clamp on ammeter?
an inductive type
What does it mean to hi-pot a conductor?
to Megger it
What can be done to create 3 phase power if one of three transformers goes out?
Use an open delta
What type of voltage is standard for a household system?
120V to ground
To control lights from 3 locations, use -----
2-3way switches and 1- 4way switch
Circuit breakers are used to ----- and ------ a circuit.
open
close
In residential wiring, how many feet are allowed between receptacles?
12 (must be within 6 feet of a receptacle)
What is the difference between an analog and a digital meter?
analog uses a needle, digital is a direct read out
Rigid pipe comes is sizes ----- to ----- and in lengths of ------.
1/2"
6"
10 feet
When bending back to back 90's and you must turn hook back around, what must be done?
the take up is reduced.
You are bending 3/4" conduit, one leg is 18", one leg is 37" and last leg is 12" the bender gain is 3 1/4", what is the length of the pipe?
18+37+12=67" (3 1/4 *2 = 6 1/2") 67-6 1/2= 60 1/2"
When the diameter of wire goes up, AWG goes -----, and resistance goes -----.
down
down
What is the difference between THW and THWN?
THWN has a nylon jacket
What is the largest AWG?
4/0
How many cubic inches are in a J box that is 5" X 5" X 2"?
25 cubic inches
You have 25A on the primary of a transformer. The primary coils are 2400 and the secondary coils are 240. What is the amperage on the secondary?
# primary/# secondary = I secondary/I primary = 2400/240 = 240/2400 = .1 * 25A = 2.5 amps on the secondary
You are going to do a segmented 90 degree bend in 20 shots, how many degrees of bend is each one?
4.5 degrees
A 4 bend saddle consists of two offsets, therefore it has ----- the shrinkage of the offsets.
twice
1 Megawatt = ----- kilowatts?
1000
The power ratings of resistors is in ------
watts
When you see a full scale deflection on a Ohmeter, it is indicating ------
0 ohms
What is the highest size of a step ladder?
20 feet
On a Wye systesm 120/208V, the 208V is the ------ reading.
phase to phase
A transformer with less winding turns on the secondary than the primary is a ------ transformer
step down
Which blue print plan locates the back-up transformer for the transformer pad outside the building?
The plot (site) plan
AC voltage is constantly changing -----
in magnitude and polarity
A thermocouple is for measuring -----
temperature
2 cell batteries connected in ----- have the same voltage.
parallel
Insulated grounding conductor is identified by -----
the color green
J-box wiring is installed so that the wire is -----
readily available
A Service Entrance Conductor, largest ungrounded conductor is 1 AWG, what minimum size is required for the ground?
6 AWG
Who enforces the electrical code?
local government
What is the smallest size EMT?
1/2"
The grounded conductor is identified by -----
white insulation
12 AWG wire, this number represents the ------
cross sectional area of the wire.
When you have a screw that is an 8/32, what does the 32 mean?
It means there are 32 threads per inch
A thermally protected motor means it is ------
sensor protected
The current capacity of a wire is determined by ----
circular mil
The maximum overcurrent devices in a panelboard is -----
42
What is the minimum depth of a grounding electrode rod?
8 feet
An overcurrent trip device must be installed in each ------
ungrounded conductor
What is the best way to cut PVC if it is in a limited area?
with nylon string
Rigid Steel Conduit (RSC) is galvanized inside and out to ------
prevent corrosion
What is the best way to mark 20' of floor use?
Use a mason line
What does DPDT stand for?
Double pole, double throw switch
A Grounding Electrode Conductor must be protected when smaller than -----
6 AWG
The purpose of overload heaters in a starter is -----
to limit the current in the motor while it's coming up to speed. It's just a resistor and a time delay contactor.
What is the main difference between a copper and aluminim conductor?
Aluminum has more resistance
When you take a current measurement, take it in ------ with the load.
series
Fuses are marked with a rating of ------ and ------
voltage
current
Voltage is a unit of -----
measurement
If there is a conflict between the prints and the specifications, which takes presidence?
specifications
What is gain when bending a 90 degree bend?
The distance that is saved or "gained" by the bend
When you have 2 batteries that are in series, what happens to the voltage?
it increases.
A HOA switch is one that has three positions -----
Hand
Off
Auto
A clamp on meter is a ------ type meter
inductive
In residential 1 phase 240V power, what is the maximum voltage to ground?
120V (phase to phase is 240V)
What is the purpose of a wire connector?
to connect and to insulate the connection
Wattage of an incandescent lamps is ------ proportional to the resistance of the filament.
inversely
Specifications may not overide the requirements of the ------
NEC (these are minimum)
If there is a full scale deflection on an analog meter, what is the resistance?
zero