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17th Edition questions - Test 1

1. BS7671 applies to
a. Equipment on board ships
b. Lightning protection of buildings
c. Lift installations
d. Prefabricated buildings

2. BS 7671 provides requirements for safety against the risk of
a. Electric shock on an aircraft
b. Shock currents on board ships
c. Fire on offshore installations
d. Shock currents in electrical installations

3. Which one ofthe following is gt a statutory regulation?
a. Electricity at Work Regulations 1989 as amended
b. The Supply of Machinery (Safety) Regulation 1992 as amended
c. Requirements for Electrical installations (BS7671)
d. Agricultural (Stationary l\/lachinery) Regulations

4. BS7671 Identifies that the cross-sectional area of a conductor shall be
determined by

a. The admissible maximum temperature
b. The nominal voltage
c. Voltage tolerances
d. The earthing system

5. A corridor containing supporting structures for cables and joints and/or other
elements of wiring systems, the dimensions of which allow persons to pass
freely throughout the entire length, is known as

a. An access pathway
b. A cable tunnel
c. An access throughway
d. Cable ducting

6. The algebraic sum ofthe currents in the live conductors of a circuit at a point
in the electrical installation is known as the

a. Residual current
b. Harmonic current
c. Line current
d. Neutral current

7. An assembly of PV arrays is defined as a
a. PV cell
b. PV array cable
c. PV generator
d. PV a.c. module

8. With reference to the nature of the supply, which one of the following can be
determined by calculation, enquiry or measurement?

a. The maximum demand of the installation
b. The rating of the circuit protective device
c. The prospective short-circuit at the origin of the installation
d. The csa ofthe tails

9. Every installation should be divided into individual circuits to
a. Prevent faults developing
b. Provide protection against electric shock ‘
c. Minimize inconvenience in the event of a fault
d. Ease installation

10. Diversity may be taken into account when considering
a. Maximum demand of the installation
b. A TN-C-S system
c. The prospective short-circuit fault current
d The number of final circuits

11. Which one of the following is not a characteristic of the supply?
a. The nature of the current and frequency
b. The earth fault loop impedance external to the installation
c. Main switch current rating
d. The nominal voltage

12. BS 7671 requires designers to take into account the frequency and quality of
maintenance an installation can reasonably be expected to receive when

a. Assessing staff numbers
b. inspecting and testing
c. Selecting staff
d. Specifying or selecting equipment reliability

13. Which one ofthe following is not part of the requirements for fault protection
a. Protective earthing
b. Protective equipotential bonding
c. Automatic disconnection
d. Protection by insulation of live parts

14. The maximum disconnection time for a TN system with a nominal voltage of 400 a.c. to Earth is

a. 0.2 second
b. 0.4 second
c. 0.5 second
d. 5 seconds

15. For a TT system, which one of the following conditions should be fulfilled for
each circuit protected by an RCD?
a. RAxIΔn x04; 50V
b. RAxIΔn x05; 50V
c. RAxId x04; 5OV
d.RAxId x05; 5OV

16. A 32 A type B circuit breaker is used to give a disconnection time of 5
seconds in a reduced low voltage system with a nominal voltage to Earth (U0)
of 55 V. What is the maximum value of earth fault loop impedance (Zs)?

a. 0.44 Ω
b. 0.34 Ω
c. 0.17 Ω
d. 0.09 Ω

17. A SELV source can be derived from which one of the following?
a. Double-wound transformer
b. Autotransformer
c. Safety isolating transformer
d. Step-up transformer

18. Which one ofthe following cannot be used as basic protection?
a. insulation of live parts
b. Barriers or enclosures
c. Protective earthing and bonding
d. Obstacles

19. ln order to provide basic protection, a horizontal top surface of a barrier or
enclosure that is readily accessible shall provide a minimum degree of protection of

a. IPXXA or lP1X
b. IPXXB or IP2X
c. IPXXC or |P3X
d. IPXXD or |P4X

20. Where arcs, sparks or particles at high temperature may be emitted by fixed
equipment in normal senrice, the equipment shall be

a. Totally enclosed in are-resistant material
b. Protected by a 30 mA RCD
c. Enclosed to at least IP55
d. Accessible only by use of a key or tool

21. Except where othenrvise recommended by the manufacturer, spotlights and
projectors rated at over 100 W and up to 300 W shall be installed at a
minimum distance from combustible materials o
a. 0.5 m
b. 0.6 m
c. 0.8 m
d. 1.0 m

22. ln locations with increased risks of fire, motors which are automatically or
remotely controlled, or which are not continuously supervised, shall be
protected against excessive temperature by

a. A protective device that is automatically reset
b. A protective device with manual reset
c. Electronic monitoring equipment that resets ’
d. Electronic monitoring equipment that restarts the motor

23. Where particular risks of fire exist, the classification for high density
occupation areas with easy conditions of evacuation is

a. BD1
b. BD2
c. BD3
d. BD4

24. When considering protection against overload, the symbol for the current
ensuring effective operation of the protective device in the conventional time is

a. lb
b. lz
c. ln
d. I2

25. For protection against ovenroltage a 230 V electricity meter should have an
impulse withstand of

a. 6 KV
b. 4 KV
c. 2.5 KV
d. 1.5 KV

26. What is the impulse category of equipment that is part of the fixed electrical
installation and other equipment where a high degree of availability is

a. I
b. II
c. III
d. IV

27. lf the construction of equipment is unsuited to the external influences of its
location, it should be

a. Given a plastic coating
b. Given a zinc finish
c. Provided with additional protection during erection
d. Supplied by SELV only

28. A permanent label to BS 951 bearing the words ‘Safety Electrical Connection
— Do Not Remove’ is not required at

a. The connection of every earthing conductor to an earth electrode
b. The point of connection of every bonding conductor to an extraneous-conductive-part
c. The main earth terminal, where separate from the main switchgear
d. A main earthing bar contained within switchgear

29. A functional switch has to be provided for each part of the circuit
a. That may require independent control
b. 1200 mm from the floor
c. For safe isolation
d. For emergency switching purposes

30. A firefighter’s switch shall be provided in the low voltage circuit supplying
exterior electrical installations and interior discharge lighting operating at

a. A voltage exceeding low voltage
b. Low voltage
c. Voltage band II
d. Medium voltage

31. A plug and socket-outlet may be used for switching off for mechanical
maintenance as long as it does not have a rating exceeding

a. 13A
b. 16A
c. 32A
d. 45A

32. If an area within an installation undergoes a 10°C rise in ambient temperature,
the effect on the current-carrying capacity of cables will be to

a. Decrease the value of Iz
b. Increase the value of Iz
c. leave Iz unchanged
d. Increase the fault current by 10 per cent

33. A multicore 70°C thermoplastic cable with 2.5 mm2 conductors supplies a
single-phase load of 20 A at 230 a.c. over a distance of 22 metres. The
voltage drop in the cable will be

a. 6V
b. 6.6V
c. 7.92V
d. 9.2V

34. Where a 3-core cable, with cores coloured brown, black and grey, is used as
a switch wire for two-way or intermediate control, the terminations of the
conductors shall be identified using

a. Red, blue and yellow tape
b. Black tape only on each core
c. Brown tape on the black and grey cores
d. Self-colour tape only

35. Which one of the following cannot be used as an earth electrode?
a. Earth plates
b. Welded reinforcement embedded in the earth
c. Earth tapes
d. Gas and water utility pipes

36. An earthing conductor buried in the ground is protected against corrosion by a
sheath, but is not protected against mechanical damage. The minimum size
copper conductor that may be installed is

a. 2.5 mm2
b. 16 mm2
c. 25mm2
d. 50 mm2

37. Assuming that both the line and protective conductors are of the same
material, for a line conductor of 10 mm2 if the protective conductor

a. 6 mm2 n
b. 10 mm2
c. 16 mm2
d. 35 mm2

38. A radial final circuit feeding socket-outlets supplying several items of data
processing equipment has a total protective conductor current in normal
service of 18mA. This circuit must have a high integrity protective conductor

a. Of cross-sectional area less than 1 mm2
b. Connected as a ring y
c. Controlled by an isolator
d. Enclosed in insulated conduit only

39. A static type uninterruptible power supply source shall comply with
a. BS3036
b. BS1361
c. BS EN 60898
d. BS EN 62040

40. Where an autotransformer is connected to a circuit having a neutral
conductor, the common terminal of the winding shall be connected to the

a. Neutral conductor
b. Line conductor
c. Protective conductor
d. Bonding conductor

41. When selecting wiring systems for safety services, the type of cable that
should be used in tire conditions should comply with

a. BS 5467
b. BS 6231
c. BS 7211
d. BS EN 50362

42. When carrying out a visual inspection of an electrical installation, which one of
the following does got have to be verified?

a. The methods of protection against electric shock
b. The electricity supplier
c. The connection of conductors
d. The presence of undervoltage protective devices

43. Certain information must be made available to persons carrying out inspection
and testing of an installation before the testing commences. One such item of
information would be

a. The name of the client
b. The name of the person who designed the installation
c. The length of cable runs in the installation
d. Any circuit or equipment vulnerable to a typical test

44. When carrying out an inspection of a new installation, it is necessary to
verify the

a. Total earth fault loop impedance for each circuit
b. Connection of conductors
c. Methods of protection against electric shock
d. Presence of diagrams, instructions and similar information

45. An insulation resistance test is to be carried out on a 3-phase 400 V circuit.
The test voltage and minimum acceptable reading would be
a. 250 V a.c. and 0.5 MΩ
b. 500 V d.c. and 0.5 MΩ
c. 500Vd.c. and 1 MΩ
c. 800 V d.c. and 0.5Ω

46. When an addition is made to an existing installation, the contractor shall
record on the Electrical installation Certificate or the Minor Electrical
Installation Works Certificate any

a. Changes in ownership
b. Records of repair over the last five years
c. Defects in the existing installation
d. Voltage drop in the longest circuit

47. After completion of a periodic inspection, the completed documentations shall
be given to the

a. Person ordering the inspection
b. Local authority
c. insurance company
d. Main contractor

48. In a room containing a bath, electrical equipment installed in zone O shall
have a degree of at least

a. IPX5
b. IP5X
c. IP7X
d. IPX7

49. A flush downlighter in the ceiling less than 2.5 m height above floor level over
a bath will need to fulfil the requirements of

a. Zone 2
b. Zone 1
c. Zone 0
d. All zones

50. Which of the following protective measures is permitted in a room containing a
bath or shower?

a. Obstacles
b. Placing out of reach `
c. Automatic disconnection of supply
d. Non-conducting location

51. In a swimming pool or other basin, the metallic covering or sheath of a wiring
system in zones 0, 1 or 2 shall

a. Not be used
b. Not be earthed
c. Be connected to the supplementary bonding
d. Have reinforced insulation

52. The requirements of Section 704 of BS 7671 apply to
a. Cloakrooms
b. Offices
c. Construction and demolition site installations
d. Toilets

53. In locations where livestock is kept, for all circuits other than socket-outlet
circuits, an RCD shall be provided with a rating not exceeding

a. 500 mA
b. 300 mA
c. 100 mA
d. 30 mA

54. Equipment on a pontoon in a marina that is subject to impact to level AG2
should have a mechanical protection code of

a. IPX4
b. IPX8
c. IP55
d. IK08

55. For marinas, the classification of external influence which does need to be considered is
a. AD
b. AE
c. AF
d. AP

56. In caravans, each final circuit shall be protected against overcurrent by a
device that disconnects

a. All live conductors in that circuit
b. The line conductors only
c. Line, neutral and protective conductors
d. The caravan and site supply system

57. Electric dodgems shall only be operated at voltages not exceeding
a. 120 V a.c. or 50 V d.c.
b. 50Va.c.or120Vd.c.
c. 110 V a.c. reduced low voltage
c. 1000 V a.c. or 1500 V d.c.

58. The requirements ofthe licensing authority should be ascertained for
a. Installations on caravan parks
b. Temporary supplies
c. Types of earthing system to be used
d. The design ofthe installation

59. I2 can be greater than 1.45 Iz when the overcurrent device
a. Is providing overload protection
b. Is a circuit-breaker
c. Is rated at over 100 A
d. Is providing fault current protection only

60. External influences coded BE are classified as
a. Nature of processed or stored materials
b. Conditions of evacuation in an emergency
c. Movement of air
d. Capability of persons

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