17th Edition 100 Questions 1. Basic Protection and Fault Protection can be provided by a SELV supply. One suitable safety source of supply would be a

A. 50V Storage battery B. 230V diesel generator C. 230/110V single-phase generator D. 230 /50V auto-transformer.

2. Where a circuit forms part of a TN system, the maximum permissible earth fault loop

impedance (Z,) for a 13 A socket outlet circuit used for portable equipment and protected by a 30amp 1361 fuse is

A 2.64 Ω B 1.84 Ω C 1.5 Ω D 2.0 Ω

3. In the event of an earth fault on a TT supply, the Fault Protection requirements of the final circuit supplying the 230 V stationary equipment are satisfied when disconnection occurs with in

A 0.4 s B 0.2 s C 1.0 s D 5.0 s.

4. The result of the earth fault loop impedance (Zs) being higher then the maximum tabulated values allowed in BS7671 is that the;

A short circuit current will not operate the protective device B current rating of the protective device must be increased C current rating of the protective device must be reduced D cable will be damaged before the protective device will operate under earth fault

conditions.

5. Which one of the following is a non-statutory document?

A HSE GS38 B Electricity at work regulation 1989 C Electricity Safety Quality and Continuity Regulations D BS7671 (2008)

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6. Type B MCB’s manufactured to BSEN60898 have an instantaneous trip current of between _____________their rated design current (In) A 2.7 to 4 times B 3 to 5 times C 4 to 7 times D 7 to 10 times

7. The nominal rating of an overcurrent protective device should be

A not less than the design current B greater than the current carrying capacity of the conductors C 1.45 times the load current D equal to the prospective short circuit current.

8. As means of isolation in a circuit it is NOT permissible to use a

A double-pole switch fuse B Fireman’s switch C semi-conductor device D a remotely switched contactor

9. The end to end resistance of the line and neutral conductors on a 2.5mm/1.5mm PVC/PVC twin and CPC cable, is measured as 0.45 Ω and 0.46 Ω, respectively. What would the expected end to end resistance of the CPC be

A 0.46 ohms Ω B 0.80 ohms Ω C 0.90 ohms Ω D 0.75 ohms Ω

10. Suitable precaution shall be taken where either a reduction in voltage or a loss and subsequent restoration of voltage A in a routine event B could cause danger C occurs infrequently D will not cause danger.

11. With in a paper mill having a conduit wiring system, insulation fault protection must be provided using an RCD having a residual operating current not exceeding A 30 mA B 300 mA C 500 mA D 750 mA

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12. Which one of the following is NOT a classification of external influence? A Current rating B Environmental conditions C Construction of building D Utilisation

13 A Functional switching device shall be provided for A Emergency Isolation B each part of a circuit that may need to be controlled independently C every socket outlet D Shop front lighting exceeding low voltage 14. Junction boxes must be accessible for inspection and maintenance. BS7671 allows for an exception provided that they A are recorded as a departure from the regulations B are recorded as an installed drawing C use maintenance free terminals D are used on lighting circuits only 15. Diversity factors may be applied to a circuit which is A not expected to be continually fully loaded B designed to carry its maximum load continually C supplying thermostatically controlled water heaters D supplying thermal storage heater 16. Where an installation incorporates an r.c.d. the label at the origin of the installation must

indicate the maximum period between tests on the circuit r.c.d. is A quarterly B monthly C annually D weekly 17. All fuses and circuits breakers shall have an indication of the A name of the manufacture B intended application C model or BS number D intended nominal current

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18 Where a TT system is in use, the preferred protective device is a A Moulded Case Circuit Breaker B Time delayed residual current device + suitable fuse C BS 1361 Type 1 cartridge fuse link D BS 88 HRC Fuse 19 Which one of the following is excluded as a protective earth electrode? A Underground structural metal work embedded in foundation B Welded metal reinforcement of concrete embedded in the earth C Earth plates D Metalwork of public water services 20 A steel earth conductor mechanically protected, but not protected against corrosion is buried in

soil. The minimum size of the earthing conductor is A 4.0 mm2 B 16 mm2

C 25 mm2 D 50 mm2

21 When testing a 100mA RCD the maximum test current applied via the test instrument will be

(I∆n) A 3 x I∆n

B 5 x I∆n C 1 x I∆n D 1.5 x I∆n 22. All circuits supplying sockets outlets up to a rating of 32 A, located within an unsupervised environment must incorporate a ____________ to reduce the risk of fault contact A fuse having a suitable time/current characteristic B Type B circuit breaker to BS EN 60898 C 30mA residual current device D switch-disconnector to BS EN 60947-3 23. The means of connection to a caravan pitch socket outlet, shall be a plug confirming to A BS EN 60309-2 B BS EN 60309-1 C BS 1363-1 D BS 5733

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24. In order to reduce the effects of eddy currents when conductors enter a ferrous enclosure, they should be so arranged that A each conductor of an individual circuit takes approximately the same value of the current B they are not individual surrounded by the ferrous material C they are terminated in the correct phase sequence D they are physically separated from the conductor of the other circuits within the enclosure 25 In agricultural and Horticultural premises all electrical wiring accessories shall have a minimum rating of A IPXXB B IP44 C IPX6 D IPX7 26 An RCD’s should be located only A in plastic enclosure only B at the origin of the supply C so that its operation will not be impaired by magnetic fields caused by other equipment D at a height of at least 450mm from the floor level 27 Electrical equipment installed in Zones 1 and 2 of communal baths or communal showers, where water jets are likely to be used for cleaning purposes, shall have a minimum degree of protection against external influences of A IPX3 B IPX4 C IPX5 D IPX6 28 The recommended mounting height for electric hookups on a tidal estuary is A 450mm above the high tide line B 600mm above the high tide line C 1000mm above the high tide line D 1250mm above the high tide line 29 Where can the electrical connection (eg flex outlet plate) be sited for a sauna heater? A Either Zones 1,2 or 3 B Zones 1 and 2 C Zones 1 D Zones 2

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30 What does the symbol represent? A Suitable for use with Fluoresecent lamps B Faulty equipment C Suitable for mounting of flammable surfaces D Fairground Supply 31 In an area where there is no vehicle movement on a caravan park, the minimum height for overload cables is A 3.5 m B 6.0 m C 7.5 m D 8.0 m 32 Basic & fault protection can be provided by A Placing out of reach B Automatic Disconnection of Supply C Double Insulation D Insulation of Live parts 33 Equipment having a protective conductor exceeding 10mA shall be connected to the supply by A Either Permanent connection or BSEN 60309-2 plug and socket B BSEN 60309-2 plug and socket only C Permanent connection only D 4mm cable or flex 34 When carrying out an inspection in accordance with BS 7671, which one of the following MUST be inspected A The presence of fire barriers B The prospective short circuit current C The maximum permissible voltage drop D Site applied insulation 35 A legible diagram, chart or table relating to an insulation must be provided to indicate the A route followed be each circuit B earth fault loop impedance of the supply C capacity of each distribution board D type and composition of each circuit

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36 An r.c.d. protected socket outlet circuit is connected to a TT earthing system. Operating the r.c.d.’s integral test button will verify A the continuity of the main earthing conductor B the effectiveness of the earth electrode C the continuity of the final circuit protective conductors D that the internal mechanism of the devise operates 37 Where a given test result fails to comply with BS 7671 part 6, the procedure to adopt after the fault has been rectified is that A the test and those that follow should be repeated B the whole sequence of tests should be repeated C only the test that indicated the fault should be repeated D the test that indicated the fault and those tests which may have been influenced by the fault that preceded it should be repeated 38 When testing a circuit of a 230v, the minimum value of insulation resistance to earth with all fuses in place and all the line and neutral conductors connected together is A 2 MΩ B 1 Ω C 0.5 Ω D 1 MΩ 39 No alteration, temporary or permanent shall be made to an existing installation unless the A electricity supplier has been informed B local authority has been informed C existing equipment is adequate for any additional load D existing equipment meets BS and BS EN standards 40 On completion of a new industrial installation, an electrical installation Certificate should be signed by A the owner or manager of the factory B a competent person or persons C the legal department representing the owner of the premises D the main building contractor 41 The frequency of the periodic inspection and testing for an installation shall be determined by the Supply company recommendations B installation’s maximum demand C nature of the supply D type of installation

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42 When carrying a fault current of 205 A, a 60 A protective device to BS 3036 should operate in A 0.1s B 0.4s C 5.0s D 500s 43 The external influence having a classification of AD7 indicates A humidity B immersion in water C dust in the atmosphere D high levels of vibration 44 A Minor Works Certificate should be issued A when an additional circuit is connected to an existing installation B for new installations connected to a single phase supplies of 100 A or less C for alterations or additions that do not extend to the provision of a new circuit D for new installations limited to domestic applications only 45 An exception to Additional Protection as required by regulation 411..3.3 is when A the socket outlet is specifically labelled for use with a particular appliance B supplementary bonding is installed C the socket outlet and cable supplying are surface mounted D the circuit is of a 16 amp radial type 46 Which one of the following is not a benefit of dividing the installation up into a number of final circuits is to A mitigate the effect of electromagnetic interference B prevent the indirect energising of a circuit intended to be isolated C avoid hazards and minimise the inconvenience in the event of a fault D make testing easier 47 Uo is correctly defined as the A The output voltage of the supplying distribution transformer B The nominal a.c. rms Line voltage to Earth C The declared voltage in the UK and Ireland D Single phase supply voltage

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48 A Line conductor is typical defined as A A conductor in an a.c. system other than a neutral or cpc B A conductor in an a.c. system including the neutral but excluding the cpc C one phase of a three phase system D A conductor in an a.c. system other than neutral or cpc or equivalent in a d.c. system, unless otherwise defined 49 The measured voltage at the farthest point of utilisation on alighting circuit in a commercial premise, fed from the public distribution network, is found to be 218. The overall voltage drop in % terms is and is ______________? A 3% acceptable B 3% not acceptable C 5% not acceptable D 5% acceptable 50 Which of the following best describes a Protective Bonding Conductor? A 16mm conductor from CCU to MET B 10mm conductor to incoming water pipe C 16mm conductor between hot and cold water pipes D 16mm conductors from the MET to and earth electrode 51 Part 6 of BS7671 2008 deals with A Special Locations B Inspection and Testing C Protection against over-current D Earthing 52 TT systems have a stated disconnection time of 0.2s, BS&^&! States that this may be increased to 0.4s where A a 30mA RCD is used in addition to overcurrent protection B Protective Equipotential Bonding is in place and disconnection time will be met by the overcurrent device only C Supplementary Bonding is installed in addition to Protective Equipotential Bonding D an earth rod and 100mA Time Delayed RCD is fitted 53 Alight fitting suitable for use in Zone 1 of a bathroom must be A SELV B a Class II fitting C IPX4 or above D RCD protected

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54 To comply with BS7671 2008, cables concealed inside a partition wall at a depth of less tha 500mm, must be A Adequately Earthed B provided with Additional Protection C Mechanically Protected D installed in Safe Zones only 55 The IP rating code for barriers covering exposed live parts inside a distribution board is A IP2X B IP4X C IPXXB D IP55 56 Which of the following is not considered to be suitable metallic screening for cables installed below plaster depth in a domestic installation A Earth Steel conduit B Earthed metal trunking C Earth metal channelling D Outer armours of SWA cable 57 The perfect type of supply for a caravan parks is A TNS B TT C TNCS D PME 58 The Scope of BS7671 2008 excludes which type of installation? A Oil rigs B Circuses C Marines D Exhibition Stands 59 Why may 13 amp BS1363 socket outlets used in a controlled laboratory environment, not require RCD Proctection? A There may be a possibility of nuisance tripping B There may be electromagnetic interference from other equipment C The workplace is controlled and is supervised by skilled persons D IT equipment may have high protective conductor current

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60 Basic protection can be achieved by A Limiting the current which can pass through the body B Ensuring all extraneous parts are at equal potential C Automatic disconnection of the supply during earth fault conditions D Separation of the supply and load by means of an isolating transformer 61 The supply circuit of insulation monitoring devices must be installed A at the furthest point of the installation B as close as practical to the origin of the installation C in series with the load D to provide protection against shock 62 Except A 0.3m B 0.5m C 0.8m D 1.1m 63 In a TP & N installation servicing an office with IT equipment and a high harmonic disturbance. How would the harmonic influence be combated? A Surge protection B Nothing because it cant be sorted C Increase the size of the neutral D Install a RCD 64 Which of the following is a method of fault protection? A Placing out of reach B Insulation of live parts C Obstacles D Reinforced insulation 65 The Max Zs for a TT system with a 300mA RCD A 1667 ohms B 500 ohms C 167 ohms D 100 ohms

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66 Regulation 314.1 states that every installation shall be divided into circuits as necessary to A Prevent danger to persons and live stock B Comply with Electricity at Work Regulations C Avoid hazards and minimise inconvenience in the event of a fault D Comply with building regulations 67 An RCD installed for the protection against fire must have a rating of A 30 mA B 100mA C 300mA D 500mA 68 Ceiling heating systems should be limited to a maximum temperature of? A 50 oC B 60 oC C 70 oC D 80 oC 69 A Residual Current Monitor (RCM) may be used in preference to an RCD where A The installation is under the control of a supervised person B Refrigeration equipment containing valuable frozen goods C Where no over-current protection is fitted D Quarterly manual RCD testing would be impracticable 70 An installation should not be protected by one RCD mainswitch controlling all overcurrent devices because A RCD have to be tested regularly B table 53.2 does not permit RCD’s to be used as an isolator C They maybe at risk from being overloaded D danger could arise from the failure of just a single circuit 71 External influence classification AA4 relates to A Presence of Flora B Atmospheric Humidity C Ambient Temperature D Light Dust 72 An active RCD to BS7671 will perform which functions in the event of a supply failure A Lock B Automatically trip to disconnect the supply C Remain in the on position but stay silent D Remain in the on position but alarm

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73 A 32amp BSEN60898 MCB has a max Zs of 1.44 ohms. Assuming that the MCB will operate instantaneously if 5 times its rated current flows, what is the level of fault current at this impedance at 230V A 32 amps B 160 amps C 67 amps D 331 amps 74 Standard Volt Drop calculations do not apply to which wiring method A Where site applied insulation is used B Busbar Trucking Systems C Cables supported by catenery wires D Mineral insulated cables 75 The three Zones for swimming pool installations are A 0,1 & 2 B 1, 2 & 3 C A, B & C D A1, B2 & C3 76 The maximum touch voltage in a RLV supply is A 50v B 110v C 25v D 230v 77 Electrical installations for trade shows and exhibitions are subject to number of risks. Part 6 of BS7671 recommends that such installations be tested A at period specified by the designer B every three months C every six months D after each erection/ assembly on site 78 The maximum length of run for a 10mm protective bonding conductor before it can exceeds 0.05Ω is A 26m B 24m C 27m D 25m

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79 For the purpose of earthing a TT or IT systems the main earthing terminal shall not be connected via an earthing conductor to A A solid metal earth plate B A metallic pipe belonging to another utility service C Structural steel D Earth rods 80 BS 1363-4 relates to which type of accessory? A Fused connection units B 13amps socket outlets C Unswitched socket outlets D Fuses 81 For cables crossing public areas and roadways at fairgrounds, the cable should be designed to withstand external influence to at least A AG1 B AG2 C AG3 D AG4 82 To reduce the risk of shock from the metalwork of Class I street located equipment, protection should be by A non-conducting location B ADS C earth-free equipment bonding D electrical separation 83 The recognised harmonised colour for Line conductors is A Blue B Grey C Brown D Black 84 A phase 4 wire system is also known as A TP & N B TNS C TNCS D TN

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85 The maximum current carrying capacity for 1.0mm twin and earth, installed to reference method C A 11.5 amps B 16 amps C 13 amps D 10.5 amps 86 1.5mm SWA 70 oC thermoplastic insulated cable, has a rated volt drop of A 25 mV/A/m B 26 mV/A/m C 21 mV/A/m D 27 mV/A/m 87 Non sheathed cables shall be enclosed in conduit or trunking, but this requirement does not apply to A Protective Equipotential Bonding conductors B Site applied insulation C Double insulated meter tails D SELV conductors 88 When carrying out a PIR on a 230v installation, the minimum value of insulation resistance to earth with all MCBs in place and the Line and Neutral conductors connected together is A 0.5 Ω B 2 MΩ C 0.5 MΩ D 1 MΩ 89 The maximum rating for an RCD at the origin of the supply mobile circus tent is A 30mA B 100mA C 300mA D 500mA 90 On completion of a new industrial installation, an Electrical Installation Certificate should be signed by A the owner or manager of the factory B a competent person or persons C the legal department representing the owner of the premises D the main building contractor

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91 The frequency of periodic inspection and testing for an installation shall be determined by the A supply company recommendations B installation’s maximum demand C nature of the supply D type of installation 92 When carrying a fault current of 205 A, a 60 A protective device to BS 3036 should operate in A 0.1s B 0.4s C 5.0s D 500s 93 The external influence having a classification of AD7 indicates A humidity B immersion in water C dust in the atmosphere D high level of vibration 94 A Minor Works Certificate should be issued A when an additional circuit is connected to an existing installation B For new installations connected to single phase supplies or 100A or less C for alteration or additions that do not extend to the provision of a new circuit D for new installations limited to domestic applications only 95 In order to avoid damage from vehicles and other users, cables supplying mooring hookup cabinets, shall be laid at recommended depth of A 450mm B 500mm C 600mm D 1000mm 96 The maximum operating temperature for thermoplastic insulated cables is A 105 oC at the sheath B 70 oC at the sheath C 90 oC at the conductor D 70 oC at the conductor

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97 Multicore cables installed in cable trunking that is flush with the floor are classed as which reference method A D B C C B D A 98 Zone 2 in a domestic bathroom extends to A 2.25m vertically from the top surface and horizontally 1.2m from the bath B 2.25m vertically from the top surface and horizontally 0.6m from the bath C 2.5m above floor level and horizontally 0.6m from the bath D 2.25m above floor level and horizontally 0.6 from the bath 99 External influence classification AD relates to Presence of A Moisture B Water C Steam D Solid foreign bodies 100 Which of the following best describes a PEB – Protective Equipotential Bond A 16mm conductor from CCU to MET B 10mm conductor to incoming water pipe C 6mm conductor between hot and cold water pipes D 16mm conductor from the MET to an earth electrode

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Answers 1 A 51 B 2 B 52 B 3 B 53 C 4 D 54 B 5 D 55 C 6 B 56 C 7 A 57 A 8 C 58 A 9 D 59 C 10 B 60 A 11 B 61 B 12 A 62 ? 13 B 63 A 14 C 64 D 15 A 65 C 16 A 66 C 17 D 67 C 18 B 68 D 19 D 69 B 20 D 70 D 21 C 71 C 22 C 72 B 23 A 73 B 24 B 74 B 25 B 75 A 26 C 76 C 27 D 77 D 28 C 78 D 29 C 79 B 30 C 80 A 31 A 81 B 32 C 82 B 33 A 83 D 34 A 84 A 35 D 85 B 36 D 86 A 37 A 87 A 38 D 88 B 39 C 89 C 40 B 90 B 41 D 91 D 42 C 92 C 43 B 93 B 44 C 94 C 45 A 95 B 46 D 96 D 47 B 97 C 48 D 98 D 49 C 99 B 50 B 100 B

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