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

This is practice test number two for the C&G 2394 - 2395 multiple choice exams. The sample test below has 40 questions, the same number as the online exam. The allowed time for the exam is 1 hour and 20 minutes. You will find the answers on the last page.

1. OSG gives the maximum stable value of Ze for a TT installation as:
a) 1660 ohms
b) 600 ohms
c) 200 ohms
d) 100 ohms

2. Which type of earthing system relies on a separately supplied earth, usually the sheathing on the cable:
a) TT
b) TN-C-S
c) IT
d) TN-S

3. Which of the following would not be one of the human senses to use during the initial verification of an addition to a lighting circuit:
a) Sight
b) Hearing
c) Taste
d) Touch

4. On a standard TT installation, the result of the resistance of the earth electrode and the rated RCD residual operating current should not exceed:
a) 25V
b) 50V
c) 110V
d) 400V

5. Which of the following protection devices is unlikely to be suited for short circuit currents in the region of 6kA:
a) BS 3036 semi-enclosed fuse
b) BS 88-3 cartridge fuse
c) BS 88-2 general purpose fuse
d) BS EN 60898 circuit breaker

6. The term given to the person responsible for an electrical system is the:
a) Competent person
b) Electrician
c) Duty holder
d) Company manager

7. Regional electricity companies quote a maximum likely value of external loop impedance (outside the consumer's installation) for a TN-S system as:
a) 0.35 ohm
b) 0.8 ohm
c) 21 ohm
d) 200 ohm

8. EAWR states that working live is acceptable unless:
a) Suitable tools are used
b) Suitable PPE is worn
c) It is reasonable in all circumstances for it to be dead
d) An engineer gives you permission

9. Overloaded windings on a 3 phase motor may be identified in the first instance by using which sense:
a) Sight
b) Smell
c) Touch
d) Taste

10. Which of the following earthing systems has the path for earth leakage currents via the earth itself:
a) TN-S
b) TNC-S
c) TN-C
d) TT

11. Which of the following is the correct voltage for carrying out an insulation resistance test on a 400V three-phase circuit terminated at an isolator?
a) 250 V
b) 400 V
c) 500 V
d) 1000 V

12. A continuity test is to be carried out and the instrument has been confirmed as being in calibration and undamaged, Which of the following is the remaining check that needs to be carried out to confirm the instrument is suitable to use?
a) It is set to 230 V a.c.
b) The battery is in a good condition
c) The leads comply with GS 38
d) It is set to read high values of resistance

13. Which of the following is the minimum short circuit test current for a low resistance ohmmeter?
a) 50 mA
b) 100 mA
c) 200 mA
d) 300 mA

14. Test instruments should be calibrated in accordance with the manufacturers instructions to ensure accurate test results. In addition to calibration which of the following should be carried out and recorded?
a) Regular conformation of the instrument`s compliance with BS 7671
b) Extension of the instrument warranty period
c) Regular instrument accuracy checks
d) Closed circuit voltage checks

15. Which of the following is the maximum voltage above which test leads must comply with the requirements of GS 38?
a) 25 V a.c.
b) 25 V d.c.
c) 50 V a.c.
d) 50 V d.c.

16. During initial verification of a TN system the installation earth conductor was recorded as 16mm2. The minimum size of main bonding conductor should be:
a) 4mm2
b) 6 mm2
c) 10 mm2
d) 16 mm2

17. Which of the following is not permitted for use as an earth electrode:
a) Underground structural metalwork
b) Metal water mains pipes
c) Lead sheaths of cables
d) Earth plates

18. Which one of the following does not need to be checked for compliance during the visual inspection of an installation:
a) presence of fire barriers
b) correct connection of the supply authority's fuse
c) routing of cables in safe zones
d) connection of single pole devices in line conductors only

19. End-to-end resistance checks would be carried out on a:
a) radial circuit
b) lighting circuit
c) ring final circuit
d) fused connection unit

20. The purpose of the test button of a residual current device is to check the:
a) Earth fault loop impedance
b) Continuity of the earthing conductor
c) Earth electrode resistance
d) Mechanical operation of the rcd