Control Panel Wiring

Electrician Trade Theory, Module-8

Posted May 15, 2025 Updated Dec 11, 2025

By Roni

6 min read

Control Panel Wiring

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Q1: Which supply indicates by the colour of conductor exhibited on Red, Blue and Black?

Supply DC 3 wire system
Single phase AC system
Supply AC system 3 phase
Apparatus AC system 3 phase

Q2: Which cable ties are used to bunch the wires?

Silk ties
P.V.C ties
Nylon ties
Cotton ties

Q3: Which device is avoided in the panel board assembly?

Sensors
Indicating lamp
Isolating switch
Push button switch

Q4: What is the name of the device marked as 'X'?

Stop button
Start button
Main contact
Auxiliary contact

Q5: What is the name of the wiring accessory used in control panel wiring?

DIN rails
G channel
Grommets
Race ways

Q6: What is the name of the device marked as 'X' in the circuit?

Contactor
No volt coil
Stop button
Over load relay trip

Q7: What is the name of the accessory used in control panel wiring?

Wire ferrules
Wire sleeves
Nylon cable ties
Cable binding strap

Q8: What is the name of the accessory used in control panel wiring?

Lugs
Thimble
Grommet
Terminal connector

Q9: Which device protects from overload and short circuit in a panel board?

Isolating switch
Time delay relay
Thermal overload relay
Miniature circuit breaker

Q10: Which switch with an actuator is operated by the motion of a machine or part of an object?

Limit switch
Toggle switch
Isolating switch
Push button switch

Q11: Which switch is operated at OFF load condition?

Limit switch
Isolating switch
Two way switch
Push button switch

Q12: What is the reason for providing two separate Earthing in panel board?

Panel board is made in metal box
Control the stray field in the panel
Reduce the voltage drop in panel board
Ensure one earthing in case of other failure

Q13: Which circuit, the limit switches are used?

Lift circuits
Street lighting
Motor control circuits
Domestic power circuits

Q14: How the control circuit voltage and power in a contactor are to be selected?

As per rated current
As per supply voltage
As per no volt coil rating
As per the type of supply

Q15: What is the criteria to select the contactor?

Type of supply
Type of load connected
Supply voltage and load
Place of use the contactor

Q16: Which accessory is used to mount MCB, OLR in the panel board without using screws?

DIN Rail
G channel
Grommets
PVC channel

Q17: Which type of device protects motors from over heating and over loading in a panel board?

Rectifier
Limit switch
Thermal relay
Electro mechanical relay

Q18: What is the use of 'G' channels in control panel?

For fixing relays
For fixing contactors
For fixing instruments
For fixing terminal connectors

Q19: What is the function of limit switch in control panel wiring?

Controls machine from over heat
Controls machine from over speed
Controls machine from over loading
Controls distance movement of any machine

Q20: Which is the standard duty cycle code of the contactor for starting and stopping the AC resistive and inductive load?

Q21: Which is the correct sequence operation of contactors for operating automatic star delta starter?

Main -> Star -> Delta -> Timer
Star -> Main -> Timer -> Delta
Main -> Timer -> Delta -> Star
Star -> Timer -> Main -> Delta

Q22: Why control panels are provided with control transformer?

To maintain rated voltage to load
To operate the auxiliary circuits
To maintain rated main supply voltage
To supply reduced voltage to power circuit

Q23: What happens, if time delay relay of a auto star delta starter still in closed condition after starting?

Starts and stop
Runs normally
Runs in star only
Runs in delta only

Q24: What is the use of PVC channel in a control panel wiring?

Mounting MCB
Mounting relays
Path way for electrical wiring and protection
Mounting double deck terminal contactor

Q25: What is the purpose of thermal over load relay in control panel?

Switching ON/OFF the circuit
Protect the circuit from earth fault
Control the circuit based on time delay
Protect the motor from over heating and loading

Q26: Why sequential control of motors is required in an industrial application?

To share more loads
To reduce power consumption
To minimise the operating cost
To increase the accuracy of operation

Q27: Which material is used to make open frame bimetallic adjustable thermostat contacts?

Silver
Brass
Copper
Bronze

Q28: What is the purpose of DIN-rail used in control panel wiring?

It provides a path way for electrical wiring
Install the high powered circuit accessories
Mounting the double deck terminal connectors
Mounting the control accessories without screws

Q29: Which device controls the operations in sequential control systems?

Timer
Relays
Contactor
Control transformer

Q30: Which DC load is represented by the DC2 standard duty cycle of contactors?

Resistive loads except motor loads
Starting and stopping of shunt motor
Starting and stopping of series motor
Starting and stopping with inching and braking

Q31: What is the purpose of control transformer used in control panel wiring?

To maintain constant terminal voltage
To supply the power to the auxiliary circuits
To control the supply voltage to the contactor
To protect the control elements from over voltage fault

Q32: How the contacts in a contactor can be engaged for working?

By manual operation
By mechanical settings
By operating electromagnet to change the position
By using bimetallic strip to change the position

Q33: Which device prevents flare out of stripped and stranded cables in the panel board?

Sleeves
Wire ferrules
Lugs and thimbles
Cable binding straps and button

Q34: How to protect the cable from insects and rats into the panel?

By using sleeve
By using Grommets
By using cable binding straps
By providing nylon cable ties

Q35: What essential feature to be considered while designing a layout of control panel?

Proper type of protection and measuring system
Inside area and number of indicating lights in front panel
Suitable method of labelling and cable harnessing
Outside dimensions and swing area of cabinet door

Q36: Why power and control wirings run in separate race ways?

To reduce heat
To reduce the radio interference
To increase the insulation resistance
To increase the current carrying capacity

Q37: Why the motor is not changing the direction, if reverse push button is pressed in forward and reverse control star delta starter?

No volt coil is not energized
Fault in forward contactor
Due to interlock in reverse contactor
No voltage exist in reverse contactor

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2nd year, Trade Theory

Theory ITI

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