JW Test Arizona
What size wire for a 20 amp breaker
#12
Biggest hand bender
1 1/4"
Ground fault protected system must operate to cause the service disconnect to open all ungrounded conductors to fault to circuit, maximum setting of the ground fault protection is _________ amperes and the maximum time delay is _________ seconds or ground fault occurs equal to or greater than 3000 amperes
1,200 amps / one second
What is the power factor for a purely resistive circuit
100%
Percentage for continuous duty
125%
Small remote ungrounded sewage pump room includes an indoor pinpoint 150 watt work light type lumineer on a 1/2 Hp, 120 volt single phase continuous duty pump motor. What is the minimum ampacity for this line single branch circuit where the indoor work light is to be used as a non continuous load
13.5 amps
Alternator turning at 3600 RPM is produced in 60 cycle voltage. How many stator poles are used in the alternator?
2 poles
Using the law of proportion you find the total current for the circuit
2.3 amps
Industrial plant with a total load 1,513kva, power factor of 87% which results in 908kvar of reactive power. How many 45kvar units will be required to correct out of phase condition without causing a leading power factor?
20 units
Counter top spaces _________ or more must have a recep
24" Article 210.52 (C)(1)
Largest solid size bare copper
4 AWG
Max amps for Control Transformers
5 Amps
Primary voltage of 480v created at 45 KVA 3 phase. Determine the maximum size circuit breaker protected transformer providing the primary only protection
70 amps table 240.6 (A) table 450.3 (B) (125% 9 amps or more)
One horsepower equals
746 watts
What is the power factor for a 3 phase load in the situation below?
76.79%
What is the max load for an overcurrent protection device
80%
Define Silicon Controlled Rectifier and its use in a variable frequency drive
A solid state device that varies current to change motor speed
Define Ground Fault Protection
A system intended to provide protection of equipment from damaging line-to-ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit
6" offset is to be formed on a 3/4" emt conduit which one of the combinations is an acceptable offset?
A. 22.5 degree with 12" center to center (2.5 multiplier) B. 30 degree with 12 1/2" center to center (2 multiplier) C. 45degree with 8 1/2" center to center (1.41 multiplier) Answer is C
Define UFER
An electrical earth grounding method. It uses a concrete encased electrode to improve grounding in dry areas
Determine the maximum rating of the motor branch short circuit and ground fault protected device, 125hp, 480v, 3 phase induction motor where the starting current has an issue with tripping. Table 430.52 value using an inverse time fix trip circuit breaker.
Answer on test 450
Their are two critically important issues involved in securing job safety
Awareness and Common sense
What following functions do arc chutes perform in relationship to the arc
Contain, divide, extinguish
Define Buck-Boost transformers
Designed to reduce (buck) or raise (boost) line voltage from 5-20%. Small single phase transformers
When correcting power factor for motors, capacitors should be installed no further than the LOAD side of the
Disconnect
How often do you need a recept in a hallway
Every 10'
Material cost for a large conduit bending job can be reduced by using what?
Field made bends
Manual motor starters are used for
Fractional-horsepower motors
When resistance is added to a circuit current _____________
Goes down
EGC (Equipment Grounding Conductor)
Has to be put in everything whenever you are running wire
Define Inrush Current
Highest current that's available when applying power
Define Overtravel
How much further the armature switch travels once it makes contact
NODODE
Normally Open Delay On De-Energize
NODOE
Normally Open Delay On Energize
A standard limit switch is made up of what
Operator head, Actuator, Body
All ungrounded service conductors must have _________ but not necessarily short circuit protection
Overload protection
Which one of the following fuses would be the best selection for a DC photovoltaic source and output circuits?
Photovoltaic solar UL2579
Apprenticeship program exist with the primary purpose of__________
Producing future craftsman
The voltage of a dual voltage motor is doubled 115v to 230v the current is ___________
Reduced by half
How do Auto Transformers work
Reduced voltage starting. Reduces the load on the motor then you can ramp it up without having a large current in rush. Start it slowly then bring it up to speed.
Auto transformer used for reduced voltage motor starting is a method of reducing current through the motor windings and _____________ during the motor starting?
Reducing load on the power distribution circuit
In Paralleling GenSets, the _________ fields are connected in _________
Series / Parallel
DODE timers are _________ if they require an external switch
Solid state
Where can't you utilize standard lock nuts and bushings
Supply side service disconnect lock nuts can't be used
If the grounded metal outlet box is _____________ and there is direct metal to metal contact between the mounting strap of the device and the grounding metal box, the equipment bonding jumper is not required
Surface mounted
If you double the voltage what happens to the current
The current gets cut in half