Second Year Final

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

An individual disconnecting means shall be provided for each controller and shall disconnect the controller. The disconnecting means shall be located _____ the controller location.

in sight from

A transformer has an efficiency of 95%. To deliver 1 kVA of power to a load, the transformer must be supplied with ____- VA of power on the primary.

1053

A three phase motor draws 28 amps at 230 volts. The power used by the motor is _____ kVA.

11.154

The OCPD for a motor branch circuit opens quickly when subjected to faults. These faults include ______. i.overloads ii.ground faults. iii. short circuits.

ii and iii only

When motors are ______ hp or greater, the motor nameplate shall include the rated horsepower.

1/8

What is the total inductance in henrys of three insuctors in parallel, with values of 15 mH, 12 h AND .8h

.0147

in a 60 Hz circuit, containing a 1.3 mH inductor, the inductive reactance is ____ ohms.

.49

The maximum cross-sectional area that can be occupied by conductor in a 40-foot run of conduit is 53% where the conduit contains _____ conductors.

1

A transformer has a 4:1 voltage ratio. If the input voltage was 456 volts, the output voltage would be ______ volts.

114

The ampacity of conductors from the generator to the first distribution device(s) containing overcurrent protection shall not be less than ____ percent of the nameplate current rating of the generator.

115

For transformers rated 1000v or less and where the secondary protection is not required the primary windings shall be protected at not more than _____ % when the primary rated current is 20 amps.

125

In a 50 Hz circuit, containing a 25 uF capacitor, the capacitive reactance is_____ ohms. Microfarads to farads

127.3239

Three separate winding sets are contained in the stator of a 3 phase motor. These are set at ______ degrees apart.

129

When a 3 phase load is drawing 48 amps at 208 volts this is a _____ load.

17.29kVA

How much current can each conductor carry? 6 current carrying 250 kcmil conductors are run in a conduit that is located in a 129 f ambient temperature location? The 75c OCPD terminations are far away from the high temp area.

176

In a circuit with 10 ohms resistance and 15 ohms inductive reactance, the impedance is ____ ohms.

18

A sine wave will hit its peak value ______ times during each cycle.

2

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.

2

A 240 volt 3 phase 15 kva load is located a distance of 350 feet from its source where the voltage is actually 236 volts. if k=12 and the wire is 8 awg calculate the voltage available at the load.

220

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

The horizontal bathtub zone in which luminaires are not permitted is _____- from the bathtub rim

3

The smallest standard size metal box that can be used for the following is a ______.

3-3/4 x 2 x 3-1/2 masonry box

Schedule 40 pvc is to be installed in a straight run between two junction boxes on the back exterior wall of a strip shopping center. The summertime temperature is 100F and the wintertime temperature is -5F. An expansion fitting would be required in this 80' run of pvc because it would expand _____ inches between winter and summer.

3.41

Emergency controls to simultaneously disconnect motor fuel dispensing equipment at attended self service facilities shall be located not more than ______ from dispensers.

30m (100 ft)

4- conductor, 10 awg mc cable is connected to a 3 pole breaker in a 208/120 volt 3 phase 4-wire panelboard and is used for a multiwire branch circuit to serve several 120-volt computers(nonlinear loads). because these circuits supply nonlinear loads, each of the four conductors in the cable (3 hots+ the neutral) can now carry only _____ amps.

32

What minimum size conductors are required to feed a 16,000 watt single phase 240 volt electric furnace operated at 240 volts? use 424.3(B). The branch circuit OCPD is a circuit breaker that is rated for 75c

4

Using the standard calculation the total load for household clothes dryers is computed at _____ VA or the nameplate rating whichever is higher.

5000

The rated secondary full load line current of a 225 kVA, three phase, 480 pri ----- 240 sec transformer is ______ amps.

541

The depth of the 24" x 24" box, shown above is 10 inches. Measured from the point in the box where the conductors emerge from the conduit, the minimum length of the conductors is ____- inches.

6

If a 4 wire wye connected supply system has a line to line voltage of a 13.5 Kv, what is the line to neutral voltage?

7800

A three phase, 240volt feeder is going to supply power to one 5hp 3 phase motor, three 2 hp 3 phase motors, and two 1 hp 3 phase motors. The minimum size conductors permitted for this feeder are ____- AWG.

8

Motor nameplate: 230/460 -V 3 phase 30 Hp supply: 3 pole breaker in a 277/480 V panel Minimum size circuit conductors are _____ AWG.

8

The smallest copper service-drop conductors that can be installed for a service are

8

A feeder supplies power to a 2 hp, 115/230-v single phase motor from a 1 pole breaker in a 208/120 3 phase 4 wire panel. Nontime delay fuses installed in the safety switch for this motor are permitted to have a maximum rating of _____ A.

80

Where lubrication and vehicle servicing is done at minor repair garages, the spave below the floor and up to 18 inches above the floor level in an unventilated pit shall be _____.

classified as class i, division i

If the current flowing through a coil of wire is increased, the magnetic field strength _____.

also increase

A set of wires ( Bk,R, BL,GR) are installed between a 3 pole sagety 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

Motor controllers must be marked with ______. i.maximum rated voltage ii. maximum hp or current rating

both i or ii

The location classification for spray application for the interior of any open or closed container of a flammable liquid is _______.

class i, division i

The classifications 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 ii

In general care areas, each patient bed location shall be provided with a minimum of ____ receptacles.

eight

Heaters are installed in motor starters to protect _____. i. the motor against overload ii. the branch circuit conductors against overload iii. the motor against short circuits and ground faults

i and ii only

Stainless steel ground rod electrodes ______. i.shall be at least 3/8 inch in diameter ii. shall be at least 10 feet in length

i only

In a purely inductive circuit, current is said to _____ the applied source voltage.

lag

A lockout can be removed by _______.

only the person who applied it

A 20 amp multiwire branch circuit is connected to breakers 1 and 3 in a 120/208 volt 3 phase 4 wire panelboard. _______ if the "hot" from breaker 3 and the neutral are conncected to a 2000 watt hand dryer load.

the load will operate normally and the breaker will not trip

A 3-pole breaker in a panel is to supply power to a 3 phase load that will pull 53 amps. The wires will be installed in a conduit with other current carrying conductors. The conduit will contain a total of 12 current carrying conductors. The conduit will be run through an area where the temperature is 124F. The smallest size wire that you can install for this load ____ AWG.

1

A certain 3 phase load draws 27.8 amps and is operating on a circuit that is fed from a 240/120 3 phase 4 wire panelboard. This load is using______ Kva of power.

11.556

What is the minimum trade size RMC permitted to be installed between two panelboards tht are 5 feet apart? The RMC will contain four 4/0 awg conductors and one 4 awg ground. all conductors are thhn/thwn

2 1/2

4 Awg thhn 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 ____ amps.

20

A single phase 480 volt duct heater is rated for 10 kVA. It is being def from a 277/480 volt three phase panel. The duct heater will draw ____ amps.

20.83

Where ( snap) switched are installed in multigang boces without permanent barriers (partitions) the maximum voltage between adjacent switches is ____ volts.

300

Motor nameplate 115/230 V single phase 3hp Supply 1 pole breaker in a 120/240 volt single phase 3 wire panel. the maximum size DETD fuses permitted are _____ A.

60

A 2 pole breaker in a 120/208 volt 3 phase 4 wire panel delivers power to aload with a rating of 22.4 kW at 240 volts. Each ungrounded conductor will carry ____ amps.

80.9

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 3 phase 4 wire panelboard. The current measured in one of the circuit conductors connected to the breaker is 15.9 amps the efficiency of this transformer is _____. %

96.96


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