18th Edition Section 2

13. What is the maximum I_Δn 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