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Wiring Installation and Earthing

Electrician Trade Theory, Module-9

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By Roni
4 min read
Wiring Installation and Earthing


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Q1: What is the minimum size of copper earth continuity conductor used in single phase domestic wiring as per BIS?

  • 3 Sq.mm
  • 3.5 Sq.mm
  • 2.5 Sq.mm
  • 1.5 Sq.mm

Q2: Which method is used to reduce earth resistance value in a existing earth?

  • Increasing the length of electrode
  • Keeping wet condition in earth pits always
  • Adding more sand and charcoal in earth pits
  • Increasing the diameter of earth electrode

Q3: Why A.C is required to measure the earth resistance by using earth resistance tester?

  • Regulate the current
  • Increase the voltage drop
  • Decrease the voltage drop
  • Avoid electrolytic emf interference

Q4: What is the formula to find voltage drop of a AC single phase wiring circuit?

  • Voltage drop = IR volt
  • Voltage drop = I²R volt
  • Voltage drop = I/R volt
  • Voltage drop = IR/2 volt

Q5: What is the maximum permissible load for a power sub circuit as per I.E rules?

  • 800 Watt
  • 1500 Watt
  • 2000 Watt
  • 3000 Watt

Q6: Which location the service connection supply leads to be connected at consumer main board?

  • IC cut out
  • Main switch
  • Energy meter
  • Distribution board

Q7: What is the type of test in domestic wiring installation?

Domestic wiring
  • Polarity test
  • Continuity (or) open circuit test
  • Insulation resistance test between conductors
  • Insulation resistance test between conductors and earth

Q8: What is the permissible leakage current in domestic wiring installation?

  • 1/5 x Full load current
  • 1/50 x Full load current
  • 1/500 x Full load current
  • 1/5000 x Full load current

Q9: Which instrument is used to test new domestic wiring installation?

  • Multimeter
  • Megger
  • Shunt type ohmmeter
  • Series type ohmmeter

Q10: What is the type of test in the wiring installation?

Wiring system
  • Polarity test
  • Open circuit test
  • Insulation resistance test between conductors
  • Insulation resistance test between conductors and earth

Q11: Where system earthing is done?

  • Generating station
  • Electroplating installation
  • Small industrial installation
  • Domestic wiring installation

Q12: What is the test to be carried out by using megger?

  • Polarity test
  • Insulation resistance test
  • Earth electrode resistance test
  • Earth conductor continuity test

Q13: What is the reason of lamp glowing dim and motor running slow in a domestic wiring circuit?

  • Open circuit in the neutral line
  • Short circuit between conductors
  • High value series resistance fault
  • Open circuit in the earth conductor

Q14: Which wiring installation the System earthing is to be done?

  • Substations
  • Godown wiring
  • Domestic wiring
  • Commercial wiring

Q15: Which method of earth resistance measurement is illustrated?

Earth resistance
  • Fall of current
  • Fall of potential
  • Current dividing
  • Potential dividing

Q16: How to control harmonic distortions in neutral connections as per IE rule?

  • Earthing through impedance
  • Providing by plate earthing
  • Increasing conductor size
  • Providing parallel earthing

Q17: What is the function of current reverser in earth resistance tester?

  • Converts A.C. into D.C
  • Reverses the polarity of D.C
  • Changes D.C. supply into A.C supply
  • Reverses the direction of rotation of the generator

Q18: What is the advantage of stranded conductor over solid conductor?

  • Cost is less
  • More flexible
  • Less voltage drop
  • More insulation resistance

Q19: How the earth resistance can be reduced?

  • Providing double earthing
  • Reducing the pit depth for earthing
  • Increasing the length of the electrodes
  • Decreasing the length of the electrodes

Q20: What is the reason for supplying AC to the electrodes for measuring earth resistance?

  • Provide electrostatic shield
  • Protect the cojis in the meter
  • Reduce the value of current in the meter
  • Avoid the effect of electrolytic emf interference

Q21: Why the pointer is not stable at zero on the scale as the megger is not in use?

  • It is not having controlling Torque
  • Provided with air friction damping
  • The deflecting torque is directly proportional to the current
  • The deflecting torque is directly proportional to the square of the current

Q22: Which is proportional for the deflection of ohmmeter needle in earth resistance tester?

  • Current in current coil
  • Current in potential call
  • Speed of the handle rotation
  • Ratio of the current in two coils

Q23: Which principle the earth resistance tester works?

  • Self induction
  • Mutual induction
  • Fall of potential method
  • Fleming's left hand rule

Q24: Why system earthing is different in utilization than equipment earthing?

  • It protects human only
  • it protects from all circuit faults
  • It is associated with current carrying conductors
  • it is connected to the non current carrying metal work

Q25: What is the effect if a person receives a shock current of 20 mA?

  • No sensation
  • Painful shock
  • Heart convulsions
  • Become unconscious

Q26: Which electrical equipment L' series type MCB's are used?

  • Geysers
  • Locomotives
  • Halogen lamps
  • Air conditioners

Q27: What is the megger reading in a dead short wiring installation?

  • 0 MΩ
  • 1 MΩ
  • 500 MΩ
  • Infinity

Q28: What is the advantage of crimping?

  • Gives neat appearance
  • Reduce load current
  • Avoid loose connections
  • Easy to replace
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1st year, Trade Theory
Theory ITI
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