C&G 2391 Unit 301 - Sample Test No:2

21. Given the following numbered tests, select the sequence in which these tests should be conducted for a new installation:- 1. functional 2. insulation resistance 3. polarity 4. continuity of final ring conductors 5. continuity of protective conductors:
a) 1,3,4,5,2
b) 4,5,3,2,1
c) 5,4,2,3,1
d) 2,3,4,5,1

22. Table 9A in the On Site Guide gives a value of 19.51 (mohm/m) for a line conductor of 2.5mm2 and a protective conductor of 1.5mm2. What would be the resistance of a circuit 25m in length when wired using these conductors:
a) 4.87 ohm
b) 487 ohm
c) 780 ohm
d) 0.487 ohm

23. Which of the following tests would be carried out 'live':
a) insulation resistance
b) earth continuity
c) prospective fault current
d) ring circuit continuity

24. An approved voltage tester can be used to:
a) Establish whether a circuit conductor is live or not
b) Determine the effectiveness of a disconnection device
c) Measure the resistance of an earth continuity conductor
d) Carry out continuity tests

25. Which of the following does not form part of the earth fault loop impedance:
a) The phase conductor
b) The earth electrode
c) The cable armouring
d) The neutral within the consumer's installation

26. An earth fault loop impedance tester should only allow current to flow for:
a) 0.4s
b) 4.0s
c) 40ms
d) 400ms

27. A 100ma RCD protecting a TT installation tested at half the rated tripping current should:
a) Not operate
b) Operate within 50ms
c) Operate within 100ms
d) Operate within 300ms

28. Which of the following requirements from GS 38 applies to test equipment which requires more than one test lead?
a) The leads must be at least 1m in length
b) The leads must have a csa of at least 1.5 mm2
c) The leads must be colour coded for identification
d) The leads must be permanently attached to the instrument

29. Which of the following correctly describes the purpose of a continuity of ring final circuit conductors test?
a) To confirm the conductors are installed as a complete ring
b) To confirm polarity is correct at each point on the circuit
c) To determine the R1+R2 value for the final circuit
d) To confirm the conductors are the correct csa

30. A test for continuity of circuit protective conductors is carried out at every point on a circuit. Which of the following describes the purpose of this test?
a) To confirm correct polarity
b) To confirm the conductors are correct csa
c) To determine the R1+R2 value for the circuit
d) To confirm exposed conductive parts are connected to the MET

31. Which of the following factors directly affects the conductor resistance of a cable?
a) Insulation and csa
b) Length and csa
c) Length and insulation
d) Load current and csa

32. Two identical cables are connected in parallel. Which of the following describes the effect on the combined conductor resistance compared to the single cable?
a) Doubled
b) Quartered
c) Halved
d) No effect

33. Which of the following factors affect the insulation resistance of a cable?
a) Conductor cross-sectional area
b) Cable length
c) Installation method
d) Load current

34. Four identical circuits are connected to a distribution board. Which of the following describes the effect on the combined insulation resistance at the DB when compared to that of a single circuit?
a) Doubled
b) Quartered
c) Halved
d) No effect

35. Control gear and interlocks should be operated when carrying out:
a) Functional testing
b) Isolation testing
c) Polarity testing
d) Continuity testing

36. Four circuits have insulation resistances of 20 Mohm, 25 Mohm, 40 Mohm and 50 Mohm. When tested together (insulation lump test) what would be the expected reading:
a) 0.135 Mohm
b) 6.5 Mohm
c) 7.4 Mohm
d) 13.5 Mohm

37. Which of the following should accompany the inspection and test certificate:
a) Two copies of test results
b) Copies of the inspection and test schedules
c) Copies of minor works certificates
d) Invoices for any remedial work carried out

38. A 230V single phase circuit supplies a light which is controlled by a passive infra red sensor. Special care must be taken before insulation resistance testing is carried out because the test may:
a) Cause the circuit breaker to trip
b) Operate the sensor and damage the light
c) Permanently damage the sensor
d) Give a false reading

39. Which of the following is not an example of an 'essential test' when carrying out minor works:
a) Prospective fault current
b) Earth fault loop impedance
c) Insulation resistance
d) Polarity

40. Digital test instruments should have an accuracy, as stated in GN3, of what percentage of full scale deflection (fsd):
a) 1%
b) 3%
c) 5%
d) 7%.