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