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City and Guilds: 2391 Sample Questions
1. Indicate THREE main items for which you would require relevant information, in order to correctly carry out an initial verification of a new installation
2. There are various documents that are relevant to the Inspection and Testing of an installation. State
a) one statutory document
b) two non-statutory documents
3. A Completion certificate should be accompanied by signed documentation regarding three stages of an installation. What are these stages?
4. State THREE areas of investigation that you would consider when carrying out a periodic inspection and test if an installation.
5. State THREE human senses that could be used during an inspection of an installation.
6. List the instruments which, during a test on an installation, gave the following readings.
a) 20 M Ohm
b) 8kA
c) 22mS
7. With reference to insulation resistance testing, state the tabulated test voltages to be applied and the minimum tabulated acceptable value of resistance for EACH of the following circuits.
a) SELV circuit
b) LV circuit up to 500V
c) LV circuit over 500V
8. List, in the correct sequence, the FIRST THREE tests that should be carried out during an initial verification on a new domestic installation.
9. The test for the continuity of a CPC in a radical circuit feeding one socket outlet using a temporary link and a milli-ohmmeter. State
a) where the temporary link is connected
b) where the milli-ohmmeter is connected
c) what the meter reading represents
10. List THREE different protective conductors that would need to be connected to the main earthing terminal of an installation.
11. The following readings were obtained during the initial test of a healthy ring final circuit
- P1 to P2 - 0.8 ohms
- N1 to N2 - 0.8 ohms
- CPC1 to CPC2 - 0.8 ohms
a) What readings would you expect after cross connection
i) Between P and N conductors at each socket outlet
ii) Between P and CPC at each socket outlet
b) What does the P to CPC reading represent
12. State the effect of
a) Conductor resistance when conductor length increases
b) Insulation resistance when cable length increases
c) Conductor resistance when conductor csa increases
13. List three precautions to be taken prior to commencing an insulation resistance test on an installation
14. An enclosure has been fabricated on site to house electrical equipment which is not exposed to water. State the IP codes that the enclosure should comply with as a minimum requirement
15. State the degree of protection provided by enclosures offering the following:
a) IPXXB
b) IP4X
c) IPX8
16. State THREE reasons for conducting a polarity test on an installation
17. Identify the earthing systems that are attributed to the following:
a) An overhead line supply with no earth
b) A multicore supply cable with a separate neutral and earth
c) A supply cable in which the functions of earth and the neutral are performed by one conductor
18. State three locations where additional requirements may apply to electrical installations
19. State what is represented by
a) Ze
b) Zs
c) R2
20. State any three functional tests that may be carried out on a domestic installation.
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