(A)maximum fault current carrying through the ground wire
(B)rated current carrying capacity of the service line
(C)depends on the soil resistance
(D)both ((A)and (c)
Ans: D
2. Earth wire or ground wire is made of
(A)copper
(B)aluminium
(C)iron
(D)galvanized steel
3. Average resistance of human body is
(A)500 ohms
(B)1000 ohms
(C)1500 ohms
(D)2000 ohms
Ans: B
4. Generally grounding is provided for
(A)only for the safety of the equipment
(B)only for the safety of the operating personnel
(C)both ((A)and (b)
(D)none of the above
Ans: C
5. Ground resistance should be designed such that
(A)grounding resistance should be as low as possible
(B)grounding resistance should be as high as possible
(C)grounding resistance should be always zero
(D)none of the above
Ans: A
6. Which of the following is not use as earth continuity conductor ?
(A) water pipes
(B) gas pipes
(C) structural steel members
(D)all of the above.
Ans : D
7. The diameter of a 50 SWG wire is closer to
(A) 0.0253 mm
(B) 0.05 mm
(C) 0.1 mm
(D) 0.5 mm.
Ans : A
8. Non-metallic conduits for wiring are generally made of
(A) rubber
(B) cork
(C) wood
(D) PVC.
Ans : D
9. PVC conduits can be buried on
(A) lime
(B) plaster
(C) concrete
(D) any of the above.
Ans : D
10. PVC conduits can be joined by
(A) solvent cement
(B) welding
(C) threading
(D) any of the above.
Ans : D
11. The maximum horse power up to which 440 V electric motors are used, is
(A) 200 HP
(B) 50 HP
(C) 20 HP
(D) 10 HP.
Ans : A
12. The earthing electrode should be situated at a place at least .......... meters away from the building whose installation system is being earthed
(A) 1.5 m
(B) 3.5 m
(C) 25 ma
(D) 100 m.
Ans : A
13. Which of the following mixture is preferred for filling around the earth electrode effective earthing ?
(A) bone meal mixture
(B) coal salt mixture
(C) saw dust sand mixture
(D) lime-stand mixture.
Ans : B
14. Inside the earth or pit, the earthing electrode should be placed
(A) vertical
(B) horizontal
(C) inclined at 450
(D) inclined at any angle other than 450.
Ans : A
15. 'Danger 440 V' plates are
(A) danger notices
(B) caution notices
(C) advisory notices
(D) informal notices.
Ans : B
16. The minimum clearance of any overhead line from the ground should be
(A) 20 m
(B) 10 m
(C) 6 m
(D) 4 m.
Ans : C
17. Earthing of electric appliances is done
(A) for the safety of human life
(B) to reduce line voltage fluctuation
(C) for protection of electric equipment
(D) for all of the above.
Ans : D
18. Earthing is used as the return conductor for
(A) telephone lines
(B) telegraph lines
(C) traction work
(D) all of the above.
Ans : D
19. The resistance of earth wire should be
(A) infinite
(B) high
(C) reasonable
(D) very low.
Ans : D
20. The earth's potential is taken as
(A) infinite
(B) supply voltage
(C) 1 volt
(D) zero.
Ans : D
21. For an EHV equipment for maintenance first it should be isolated and connected to ground because
(A)to provide low impedance
(B)to discharge the charging capacitance to ground
(C)protection for operating personnel
(D)both ((B)and (c)
Ans: D
22. When earth fault occurs
(A)voltage potential at the earth mat increases due to grounding
(B)voltage potential at the earth mat decreases due to grounding
(C)voltage potential at the earth mat remains zero irrespective of fault
(D)none of the above
Ans: A
23. The objective of earthing or grounding is
(A)to provide as low resistance possible to the ground
(B)to provide as high resistance possible to the ground
(C)to provide flow of positive, negative and zero sequence currents
(D)none of the above
Ans: A
24. Moisture content in the soil __ the earth soil resistance
(A)increase
(B)decrease
(C)does not affect
(D)none of the above
Ans: B
25. Factors on which soil resistance depends
(A)depth of the electrode
(B)moisture
(C)Nacl
(D)all the above
Ans: D
