18th Edition Mock Exam Test


You have 120 minutes (2 hours) to answer 60 18th Edition Questions. You must score at least 36 to pass. You may check answers after each question or wait until the end of the test to view your results. Click the start button to begin. Best of luck!

Your Progress

Tests Taken

Last Score

Average Score

18th Edition Mock Tests

18th Edition Mock Exam Test Questions (Printer-Friendly)

Quick view of test questions. Click question box to reveal correct answer.
1. BS 7671:2018 applies to electrical installations in Mark one answer
A Aircraft
B Mines and quarries
C Public premises
D Ships
Correct Answer: C Public premises
Explanation:
2. Protection against direct contact may be provided by Mark one answer
A Basic protection
B Fault protection
C Overcurrent protection
D Protection against thermal effects
Correct Answer: A Basic protection
Explanation:
3. The selection of protective equipment would NOT include consideration of the effects of Mark one answer
A Earth fault current
B Equipment costs
C Overcurrent
D Undervoltage
Correct Answer: B Equipment costs
Explanation:
4. The interval between initial verification and the first periodic inspection of an installation is determined by Mark one answer
A The Local Authority Building Control
B The client
C The designer
D The installer
Correct Answer: C The designer
Explanation:
5. A cable support consisting of a series of transverse supporting elements rigidly fixed to main longitudinal supporting members is Mark one answer
A Cable ducting
B Cable ladder
C Cable tray
D Cable trunking
Correct Answer: B Cable ladder
Explanation:
6. The magnitude of current to be carried by a circuit in normal service is Mark one answer
A Design current
B Overload current
C Protective conductor current
D Short circuit current
Correct Answer: A Design current
Explanation:
7. Protection against electric shock under single fault conditions is Mark one answer
A Basic protection
B Emergency stopping
C Fault protection
D Protective separation
Correct Answer: C Fault protection
Explanation:
8. When assessing the maximum demand of an installation account may be taken of Mark one answer
A Arrangement of live conductors
B Discrimination
C Diversity
D Type of earthing arrangement
Correct Answer: C Diversity
Explanation:
9. Every installation shall be divided into circuits in order to Mark one answer
A Mitigate the effects of EMI
B Prevent insulation faults
C Reduce electricity costs
D To meet the requirements of the NICEIC
Correct Answer: A Mitigate the effects of EMI
Explanation:
10. Electrical equipment in, for example, kiosks or shops within shops need to be assessed with regards to Mark one answer
A Compatibility
B Continuity of service
C Maintainability
D Safety services
Correct Answer: A Compatibility
Explanation:
11. Which of the following is NOT recognised as a source for a safety service. Mark one answer
A Independent generator sets
B Primary cells
C Storage batteries
D The normal DNO supply
Correct Answer: D The normal DNO supply
Explanation:
12. An assessment for continuity of service must include Mark one answer
A Details of the installer
B Details of the supplier
C Number of circuits
D Selection of cable type
Correct Answer: C Number of circuits
Explanation:
13. Automatic disconnection of supply provides protection against Mark one answer
A Electric shock
B Overload
C Thermal effects
D Undervoltage
Correct Answer: A Electric shock
Explanation:
14. Basic insulation of live parts or barriers or enclosures provide Mark one answer
A Basic protection
B Fault protection
C Impact protection
D Thermal protection
Correct Answer: A Basic protection
Explanation:
15. A 20A final circuit fed by a 230 V a.c. TT system must disconnect, in the event of an earth fault, within a maximum time of Mark one answer
A 0.1 s
B 0.2 s
C 0.4 s
D 1 s
Correct Answer: B 0.2 s
Explanation:
16. A 13A socket outlet does NOT need to be additionally protected by an RCD provided it is Mark one answer
A Not for use outdoors
B Only to be used by ordinary persons
C Splashproof
D Subject to a documented risk assessment
Correct Answer: D Subject to a documented risk assessment
Explanation:
17. The maximum earth loop impedance for a distribution circuit protected by a 32A BS 88-3 fuse is Mark one answer
A 0.91 Ω
B 1.37 Ω
C 1.6 Ω
D 1.7 Ω
Correct Answer: C 1.6 Ω
Explanation:
18. The maximum rating of an RCD required to protect a230 V TT installation where the earth fault loop impedance is 150 Ω is Mark one answer
A 100 mA
B 30 mA
C 300 mA
D 500 mA
Correct Answer: C 300 mA
Explanation:
19. The maximum disconnection time for circuits supplied by a reduced low voltage system is Mark one answer
A 0.2 s
B 0.4 s
C 1 s
D 5 s
Correct Answer: D 5 s
Explanation:
20. A 16A BS EN 60898 Type B circuit breaker used to protect a three-phase reduced low voltage circuit is subject to a maximum earth fault loop impedance value of Mark one answer
A 0.33 Ω
B 0.38 Ω
C 0.65 Ω
D 0.75 Ω
Correct Answer: D 0.75 Ω
Explanation:
21. For the protective measure of electrical separation, the voltage of a separated circuit must not exceed Mark one answer
A 1000 V
B 230 V
C 400 V
D 500 V
Correct Answer: D 500 V
Explanation:
22. Which of the following sources of supply would be suitable for SELV and PELV circuits? Mark one answer
A A low voltage d.c. supply
B A safety isolating transformer
C Private generator at 110 V a.c
D Public supply at 230 V a.c
Correct Answer: B A safety isolating transformer
Explanation:
23. Which of the following formulae is used where there is doubt regarding the effectiveness of supplementary bonding? Mark one answer
A R ≤ 50 V/Ia
B R ≤ 50 V/In
C R ≤ 50 V/Iz
D R ≥ 50 V/Ia
Correct Answer: A R ≤ 50 V/Ia
Explanation:
24. In order to protect against burns, a non-metallic electrical part intended to be touched but not hand held should not attain a surface temperature in excess of Mark one answer
A 65 °C
B 70 °C
C 80 °C
D 90 °C
Correct Answer: C 80 °C
Explanation:
25. The disconnection time for a 16.0 mm² conductor having a 'k' factor of 115 and carrying a fault current of 13 kA is Mark one answer
A 0.0125 s
B 0.02 s
C 0.14 s
D 2.26 s
Correct Answer: B 0.02 s
Explanation:
26. The minimum impulse withstand voltage for a 230 V electricity meter is Mark one answer
A 1.5 kV
B 2.5 kV
C 4 kV
D 6 kV
Correct Answer: D 6 kV
Explanation:
27. A conductor marked green-and-yellow throughout its length with additional blue markings at the termination is a Mark one answer
A Circuit protective conductor
B Line conductor
C Neutral conductor
D PEN conductor
Correct Answer: D PEN conductor
Explanation:
28. The notice relating to an RCD requires the device to be operated via its test button Mark one answer
A Annually
B Half yearly
C Monthly
D Quarterly
Correct Answer: D Quarterly
Explanation:
29. One method of protecting a cable, that passes through a ceiling joist from damage, is to install it at a vertical distance from the top or bottom of the joist of at least Mark one answer
A 10 mm
B 25 mm
C 30 mm
D 50 mm
Correct Answer: D 50 mm
Explanation:
30. The derating factor for a cable surrounded by thermal insulation for 200 mm is Mark one answer
A 0.5
B 0.51
C 0.63
D 0.78
Correct Answer: C 0.63
Explanation:
31. Where underground telecommunication and power cables cross, the minimum clearance to be maintained between them is Mark one answer
A 0.5 m
B 100 mm
C 200 mm
D 50 mm
Correct Answer: B 100 mm
Explanation:
32. The magnetic circuit of an RCD shall enclose Mark one answer
A All circuit conductors
B All line conductors
C All live conductors
D PEN conductors
Correct Answer: C All live conductors
Explanation:
33. Where an RCD is used for protection against fire, it shall have a maximum rating of Mark one answer
A 100 mA
B 30 mA
C 300 mA
D 500 mA
Correct Answer: C 300 mA
Explanation:
34. Which of the following devices may only be used for functional switching? Mark one answer
A A 16A plug and socket-outlet
B A 16A plug and socket-outlet
C A BS EN 60898 circuit breaker
D A device with semi-conductors
Correct Answer: D A device with semi-conductors
Explanation:
35. A firefighter's switch should be mounted above ground level at a height of Mark one answer
A 2.25 m with the switch OFF position at the top
B 2.75 m with the switch OFF position at the bottom
C 2.75 m with the switch OFF position at the top
D 2.75 m with the switch ON position at the top
Correct Answer: C 2.75 m with the switch OFF position at the top
Explanation:
36. The minimum sise of a buried copper earthing conductor not protected against mechanical damage or corrosion is Mark one answer
A 10 mm²
B 16 mm²
C 25 mm²
D 50 mm²
Correct Answer: C 25 mm²
Explanation:
37. The minimum sise of a protective conductor with a 'k' factor of 143 which disconnects in 0.3 s at a fault current of 800 A is Mark one answer
A 10.0 mm²
B 2.5 mm²
C 4.0 mm²
D 6.0 mm²
Correct Answer: C 4.0 mm²
Explanation:
38. A distribution board containing circuits with high protective conductor currents shall have the information regarding these circuits positioned so as to be visible to Mark one answer
A A person modifying or extending a circuit
B An inspector
C The Distribution Network Operator
D The user of the installation
Correct Answer: A A person modifying or extending a circuit
Explanation:
39. The earthing conductor for an installation supplied from a TN-S system is 16 mm². The minimum sise of a main protective bonding conductor is Mark one answer
A 10 mm²
B 16 mm²
C 25 mm²
D 6 mm²
Correct Answer: A 10 mm²
Explanation:
40. An installation and its generator are not permanently fixed. In a TN, TT or an IT system an RCD shall be installed with a maximum rating of Mark one answer
A 100 mA
B 30 mA
C 300 mA
D 500 mA
Correct Answer: B 30 mA
Explanation:
41. Control equipment incorporating protection against overload shall be provided for every motor having a rating exceeding Mark one answer
A 0.37 kW
B 10 kW
C 100 W
D 37 W
Correct Answer: A 0.37 kW
Explanation:
42. The inspection of an installation is NOT made to ensure Mark one answer
A Compliance with section 511 of BS 7671
B That equipment is correctly selected and erected
C That it is not visible damaged or defective
D That the requirements of the ESQCR are met
Correct Answer: D That the requirements of the ESQCR are met
Explanation:
43. The minimum value of insulation resistance and the applied test voltage for a 400 V circuit is Mark one answer
A 0.5MΩ at 250 V d.c
B 1.0MΩ at 1000 V d.c
C 1.0MΩ at 500 V a.c
D 1.0MΩ at 500 V d.c
Correct Answer: C 1.0MΩ at 500 V a.c
Explanation:
44. Where surge protective devices cannot be disconnected for insulation resistance testing, the minimum value of insulation resistance and the applied test voltage are Mark one answer
A 0.5 MΩ at 250 V d.c
B 1.0 MΩ at 250 V d.c
C 1.0 MΩ at 500 V a.c
D 1.0 MΩ at 500 V a.c
Correct Answer: B 1.0 MΩ at 250 V d.c
Explanation:
45. The correct connection of socket-outlets and similar accessories is established by Mark one answer
A Functional testing
B Insulation resistance testing
C Polarity testing
D RCD testing
Correct Answer: C Polarity testing
Explanation:
46. An installation is to have the following tests carried out: 1. polarity. 2. cpc continuity 3. earth electrode resistance. 4. insulation resistance. The correct sequence for these tests is Mark one answer
A 1, 2, 3, 4
B 2, 4, 1, 3
C 3, 1, 4, 2
D 4, 2, 3, 1
Correct Answer: B 2, 4, 1, 3
Explanation:
47. The verification of voltage drop may be achieved by Mark one answer
A Functional testing
B Measuring the circuit impedance
C Measuring the prospective fault current
D Use of a voltmeter
Correct Answer: B Measuring the circuit impedance
Explanation:
48. A 13A socket-outlet may be installed in a bathroom if it is installed beyond the boundary of zone 1 by a horizontal distance of Mark one answer
A 0.50 mm
B 0.60 mm
C 2.25 m
D 3.0 m
Correct Answer: D 3.0 m
Explanation:
49. The external influence code for zone 0 of a swimming pool is Mark one answer
A AD8
B AE6
C AF2
D AG3
Correct Answer: A AD8
Explanation:
50. Cables buried in arable land on a farm should be at a minimum depth of Mark one answer
A 0.5 m
B 0.6 m
C 1.0 m
D 6 m
Correct Answer: C 1.0 m
Explanation:
51. Electrical equipment installed outside in a caravan park shall have a mechanical impact code of at least Mark one answer
A IK01
B IK03
C IK06
D IK08
Correct Answer: D IK08
Explanation:
52. Socket-outlets in a marina shall be protected Mark one answer
A BS 3036 fuses only
B In groups by RCDs
C Individually by RCDs and overcurrent devices
D Residual current monitoring devices
Correct Answer: C Individually by RCDs and overcurrent devices
Explanation:
53. Temporary installations of exhibitions should inspected and tested Mark one answer
A After each assembly on site
B At intervals during use
C Before disassembly
D Only after a fault has occurred
Correct Answer: A After each assembly on site
Explanation:
54. The flexible cable for connecting a mobile workshop to the supply shall have a minimum cross sectional area of Mark one answer
A 1.5 mm² aluminium
B 1.5 mm² copper
C 2.5 mm² copper
D 4.0 mm² copper
Correct Answer: C 2.5 mm² copper
Explanation:
55. A periodic inspection for a frequently used caravan should be carried out Mark one answer
A Annually
B Every three years
C Monthly
D Quarterly
Correct Answer: A Annually
Explanation:
56. All final circuits in a amusement park for lighting and socket-outlets and mobile equipment up to 32 A must have additional protection by Mark one answer
A 30 mA or less RCDs
B 300 mA or less RCDs
C 32 A BS EN 60898 circuit breakers
D BS 88 fuses
Correct Answer: A 30 mA or less RCDs
Explanation:
57. Heating unit in ceilings shall have a degree of protection of at least Mark one answer
A IP1X
B IP2X
C IP3X
D IP4X
Correct Answer: A IP1X
Explanation:
58. A 16 A BS 88-3 fuse carrying a fault current of 100 A will disconnect in Mark one answer
A 1 s
B 2 s
C 3 s
D 4 s
Correct Answer: C 3 s
Explanation:
59. The maximum permissible voltage drop for a 400 V motor circuit is Mark one answer
A 11.5 V
B 12 V
C 20 V
D 6.9 V
Correct Answer: C 20 V
Explanation:
60. The maximum value of earth fault loop impedance for a 32 A BS EN 60898 type B circuit breaker, for comparison with test values is Mark one answer
A 0.54 Ω
B 0.68 Ω
C 1.09 Ω
D 1.37 Ω
Correct Answer: C 1.09 Ω
Explanation:

You have 120 minutes (2 hours) to answer 60 18th Edition Questions. You must score at least 36 to pass. You may check answers after each question or wait until the end of the test to view your results. Click the start button to begin. Best of luck!