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Worksheets18th Edition Section 2
Total questions: 15
Worksheet time: 45mins
13. What is the maximum IΔn for and RCD protecting 16 A mobile equipment used outdoors?
100mA
30mA
300mA
500mA
14. Which of the following is a method of fault protection?
Placing out of reach
Protection by double or reinforced insulation
Protection by obstacles
Insulation of live parts
15. With which of the following methods can both basic and fault protection be achieved?
SELV
Insulation of live parts
FELV
Protection by non-conducting location
16. The protective measure by electrical separation provides
Fault protection only
Basic protection only
Fault and basic protection
Undervoltage
17. The maximum permissible earth fault loop impedance on a TN system for a socket outlet, used for hand-held equipment and protected by a 20 A fuse to BS 3036 is
1.10 Ω
1.47 Ω
1.68 Ω
2.70 Ω
18. The maximum disconnection time for a 16 A final circuit, where U0 = 230 V ac, forming part of a TN system is
5 s
0.2 s
0.4 s
0.1 s
19. Extraneous-conductive-parts are provided with protective equipotential bonding to ensure that
The parts are completely isolated from earth
Dangerous potential differences are reduced
The water mains can be used as auxiliary earth electrodes
There is no connection with the circuit protective conductors
20. Basic protection can be provided by
Protective bonding conductors
Barriers and enclosures
A non-conducting location
The use of Class II equipment
21. Where there is a danger of fire due to the nature of stored materials, a 100 W spotlight shall be installed at a minimum distance from combustible materials of
0.5m
0.8m
1.0m
2.0m
22. The maximum permitted surface temperature for an item of non-metallic equipment, intended to be touched, is
55 oC
65 oC
70 oC
80 oC
23. 13A socket-outlets to BS 1363 are to be supplied through a ring-final circuit protected by a 32A BS EN 61009 device
What is the minimum current carrying capacity (IZ) for each conductor under normal load conditions when considering protection against overcurrent
16A
20A
24A
32A
24. Which one of the following is not a situation where overload protection devices may be omitted for safety reasons?
A circuit supplying a fire extinguishing device
The supply to computers in an office environment
The supply circuit of a lifting magnet
The secondary circuit of a current transformer
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26. Where the nominal voltage of an installation is 230 V, the required minimum withstand voltage for Category II equipment for overvoltage protection is
1.5 kV
2.5 kV
4.0 kV
6.0 kV
27. Which one of the following situations is likely to cause severe, temporary overvoltage in an installation?
Loss of line conductor in a low-voltage system
Loss of protective conductor in a high voltage system
Loss of neutral conductor in a low voltage system
Loss of line conductor in a high voltage system
