Final Exam Set 2
In a 60hz circuit containing a 1.3mH inductor the inductive reactance is_______ ohms.
.49
Individual dry-type transformers rated over 112 1/2 kVA shall be enclosed in a fire resistant room with materials having a ____- hour minimum fire rating
1
When motors are _____ hp or greater, the motor nameplate shall include the rates horsepower.
1/8
A transformer has a primary rated voltage of 240 and a secondary rated voltage of 115 volts. if 209 volts is applied to the primary,_____ volts is induced in the secondary.
100.15
A certain 3 phase load draws 27.8 amps and is operating on a circuit that is fed from a 240/120-volt 3 phase 4 wire panel board. This load is using ____ KVA of power.
11.56
What maximum size inverse time circuit breaker is permitted for a single phase 7.5 hp motor operating at 208 volts.
110
Motor Nameplate: 115/230-v single phase 1 1/2 hp Supply: 1 pole breaker in a 120/240-v 1 phase 3- wire panel sho cord is used to connect the motor. The minimum size conductors permitted in the cord are _____ awg.
12
Motor nameplate: 208-230/460v 3 phase 5 hp supply: 3 pole breaker in a 120/208 v 3 phase 4 wire panel minimum size circuit conductors are _____ awg.
12
Underground service laterals that are installed as direct buried cable and covered with 42 inches of dirt shall also have a warning ribbon installed atleast ____ inches above the cable.
12
When a 3 phase load is drawing 48 amps 208 volts, this is a _____load.
17.3 KVA
Where a 2/0 AWG THHN/ THWN copper conductor is inside a panelboard and connected to a breaker, it can carry ____ amps of current.
175
A 80 gallon 19.7KW water heater is operated at its rated voltage when connected to a 2 pole breaker ina 120/240 volt panel. The smallest copper THHN/THWN conductors permitted to feed this equipment is ______ AWG.
2
What is the minimum trade size RMC permitted to be installed between two panelboards that are 5 feet apart? The RMC will contain (4) 4/0 AWg conductors and one 4 AWG ground. All conductors are THHN/THWN.
2 1/2
Your body has a resistance of about 50,000 ohms between your hands. you complete a 120 volt circuit by holding the neutral in one hand and the "hot" in the other hand. the current flowing in your body is about______ mA and is sufficient to cause a mild shock
2.4
4 AWG THHN/THWN copper conductors are run underground to serve parking lot lighting. the circuit is connected to a 30 amp safety switch that is fused with 20 amp fuses. The rating of the branch circuit is _____.
20
The maximum current that a 240-volt 3 phase generator can deliver is 60 amps. The rating of this generator is ____ KW
25
How much current can each conductor carry? Four (4) current carrying 500 kcmil THHN conductors are run in a pipe that is located in a 125 F ambient temperature location? The 75C OCPD terminations are far awat from the high temp area.
261
A transformer has a 208/120-volt wye secondary. The transformer is delivering 75 amps of line current to a 3 phase load. This 3 phase transformer must be rated for at least _____ KVA to avoid being overloaded.
27.02
What minimum size schedule 80 pvc conduit is required for a 65' run? The conduit will contain three 350 kcmil, one 3/0 and one #2 thhn/thwn conductors.
3
A metal box containing the following one- 14-2 w/ ground no cable secured with a rome connector one- PVC conduit containing the following conductors two-14 awg conductors spliced to the NM cable with wire nuts two-12 awg conductors terminates on a receptacle one-12 awg equipment grounding conductor
3 1/2 deep masonry box
You are to install FMC between two equipment enclosures. You dont know how many or what size wires will have to be pulled into the flex. If you install the largest flex available this is trade size ________.
4
The rated secondary full load line current of a 225 KVA, three phase, 480 primary 240 secondary transformer is ____ amps.
541
In a circuit with 25 ohms resistance and 50 ohms capacitive reactance, the impedance is ____ ohms.
55.90
Motor nameplate info: 115/230-V 1 phase 3 hp supply: 1-pole breaker in a 120/240-v, 1 phase, 3 wire panel. The maximum size DETD fuses permitted are ______ A.
60
The minimum size conductors permitted to be run between a generator and a fused safety switch are ______ AWG or kcmil. The 3 phase, 300 KVA generator delivers 480 volts.
600
If a 4 wire eye connected supply system has a line to line voltage of 13.5 kV, what is the line to neutral voltage?
7,800
The maximum size circuit breaker permitted by Note 1. to NEC Table 450.3 (A), to protect the primary of a 4160 to 480-V, 3 phase 75 KVA transformer is _____ amps. The transformer has an impedance of 1.7% and is installed in a nonsupervised location.
70
A 15 kVA 1 phase load (2-pole breaker) has a rated voltage of 208 volts. The load will pull ____ amps when supplied from a circuit in a 208Y/120-volt 3-phase, 4 w panelboard.
72.1
A 120/208 volt 3 phase 4w panelboard is fed by a 45 kva transformer . The existing loads are as follows: A phase is 46 amps, B phase is 79 amps and c phase is 92 amps. how many more amps of load could you add to a phase without overloading the transformer?
79
A 19.8 3 phase load is supplied from THHN/THEN copper circuit conductors that are connected to a 3 pole breaker in a 120/208 volt 3 phase 4 wire panel board. The load is located 152 feet from the one. the smallest circuit. inductors you can use to supply the load are _____ awg. The specifications limit the voltage drop to 1.8%. Use K = 10.86 to solve this problem.
8
A three phase 240-volt feeder is going to supply power to one 5 hp 3 phase motor three 2 ho 3 phase motors and two 1 up motors. the minimum size conductors permitted for this feeder are _____ AWG
8
The smallest copper service drop conductors that can be installed for a service are_____.
8
A branch circuit supplies power to a 2 hp, 115/230-V, single phase motor from a 1-pole breaker in a 208/120-V,3ph, 4-wire panel. Nontime-delay fuses for this circuit would have a maximum permitted rating of ______ A.
80
What is the full load current of a 230v, 3 phase 30 HP squirrel cage motor.?
80
A single phase transformer requires 32 amps at 480 volts on the primary to delivery 120 volt power to a 14.6 kW load. The efficiency of this transformer is ____%
95
A transformer has a primary rating of 480 volts and supplies 240 volts to a 7.4 KVA load. The circuit that is connected to the primary originates from a 2 pole circuit breaker in a 277/480 volt 3 phase 4 wire panel board. The current measured in one of the circuit conductors connected to the beaker is 15.9 amps. The efficiency of this transformer is _____%
96.96
Which of these trade size 1 1/4 raceways has the largest cross sectional area?
LFMC
Two lighting circuits are supplied from a multi wire branch circuit that originates in a 120/240 volt, 1 phase, 3 wire panel board. Two, 20 amp, 1 pole breakers are installed in spaces 22&24 for the multiwire circuit. Circuit 22 has 2600 watts of lights connected to it, and circuit 24 has 2100 watts of lights connected to it. Which of the following should happen to circuit 22?
an overload will occur and the beaker will trip
The service disconnecting means for a 3-phase service is permitted to consist of _____. i.a main breaker panel board with eight individual 3 pole circuit breakers ii. not more than 6 separated circuit breaker enclosures each with a 3 pole breaker iii. a fusible switchboard with a maximum of 6 switches
any of the above
If a luminaire is listed for use in a wet location it can be installed in a _____ location. i.wet ii.damp iii.dry
any of these
Where a conduit emerges from the earth or concrete under a gasoline pump, a seal must be installed_____ after the conduit emerges for the earth or concrete
as the first fitting
A set of wires (black red blue green) are installed between a 3 pole safety switch and a 3 phase motor. The direction of rotation of the motor can be changed by swapping the _____ wire connections on the load side of the switch.
black and blue
The classification of a location where ignitable concentrations of flammable liquid produced vapors or combustible liquid produced vapors exist under normal operating conditions, is______.
class i, division i
buried raceways and cables under class i locations in bulk storage plants shall be considered to be within a _____ location
class i, division i
A change in the magnetic field surrounding the conductor induces a voltage in the conductor. This induced voltage in known as _____.
counter emf
Your only available grounding electrode is the metal underground water pipe from the water utility. You are required by the NEC to have one other grounding electrode for your service. You could use which of the following driven electrodes? i.8ft trade size 3/4 rigid metal conduit ii. 10' by 5/8 inch copper-clad ground rod
either i or ii
The unit of measure for capacitance is_____.
farads
_____ is the output of an AC generator measured in cycles per second
frequency
When spray application equipment cannot be operated unless exhaust ventilation system is operating and functioning properly and spray application is automatically stopped if the exhaust ventilation system fails the system is said to be ______
interlocked
In and inductive circuit the current _____ the applied voltage.
lags
______ torque is the torque a motor produces when the rotor is stationary and full power is applied to the motor.
locked-rotor
The FLA shown on a motor nameplate is used to size _____.
overload protection
"Heaters" are installed in motor starters to perform all of the following functions except______.
protect the motor against the ground faults
Which of the symbols shown below is used to represent am inductor in a schematic circuit?
resistance
A lockout can be removed by _____
the person who applied it
The service point is located at the _____. The power company owns the pole mounted transformer and has installed the service drop to a weather head on the customers building
weather head
