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C&G 2391 MOCK exam - Paper ONE with answers

21.
- a) What documentation / information would you need in order to carry out the inspection and verification? (5 marks)
- b) What consideration should be given to the existing installation from which this new installation is fed? (4 marks)
- c) Where should the documentation / information be located? (3 marks)
- d) What notable details regarding this installation should have been included on such documentation? (3 marks)

22. The test results shown in the table below were obtained from the workshop ring final circuit continuity test. (For the first five sockets ONLY)
State whether the readings for each socket are satisfactory or unsatisfactory, giving reasons for those readings deemed to be unsatisfactory (I5 marks)
(Note - Phase, Neutral and CPC loops end to end measurement = 0.8 ohms)
2391 exam paper

23.
- a) Describe all the steps required to carry out an insulation resistance test on this workshop installation. (8 marks)
- b) The test result indicates an overall value of 1.60 MQ. State, with reasons, what actions, should be taken (if any). (7 marks)

24. The two PIR controlled security lights are each wired on its own radial circuit.
- a) List ALL the component parts of the earth fault loop path associated with one of these circuits in the event of a fault to earth. (8 marks)
- b) If the maximum value of earth fault loop impedance for this circuit is 3.0 ohms and an earth fault causes a current of 200 A to flow. Show by calculation if this value will disconnect the circuit in the required time? (7 marks)

25. State FIVE areas of inspection for this installation that should be carried out prior to testing. (15 marks)

26. An earth fault loop impedance test on the workshop fluorescent lighting circuit has been conducted but no reading can be obtained, as the 6A Type B MCB trips repeatedly. Explain
- a) Why this is the case? (8 marks)
- b) How this problem may be overcome in order to conduct the test? (7 marks)

Answers are on the following pages

 

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