18th Edition Section 3

28. The maximum temperature at the conductors of thermoplastic insulated cables is:      

• 90°C

• 70°C

• 105°C

• 60°C

29. What is the minimum level of IP protection provided by a trunking system for the protection of non-sheathed circuit cables?

• IP2X

• IP3X

• IP4X

• IP5X

 

30. A warning notice of maximum voltage present must be fixed to

•   Where a nominal voltage of 230 V to earth exists where it would not normally be expected

• 400V between line conductors

• 230V single phase in a domestic property

• Single-phase motors above 10 kW

31. A legible diagram, chart of table relating to an installation must be provided to indicate

• The location of all fixed equipment for testing purposes

• Any circuit of equipment vulnerable to a typical test

• The location of all portable equipment for testing purposes

• That the original installation design has not changed

32. A heater takes a design current of 32 A over a run of 15 metres using 4 mm² two-core cable having a rated voltage drop of 11 mV/A/m. The total actual drop will be

• 9.6 V

• 6.0 V

• 5.28 V

• 2.5 V

33. What is the maximum preferable DC power supply system voltage for an auxiliary control circuit?

• 50 V

• 110 V

• 220 V

• 277 V

34. A cable joint must be accessible if it is

• Designed to be buried in the ground

• Made by welding, soldering or brazing

• Compound-filled or encapsulated joint

• Enclosed in a screw terminal junction box

35. Which one of the following can be used as a device for emergency switching?

• Semiconductor devices to BS EN 50428

• 20 A plug and socket-outlet to BS EN 60309

• Switched fused connection unit to BS EN 1363-4

• Unswitched fused connection unit to BS EN 1363-4

36. Where RCDs are operated by ordinary persons which type of device should not be used

• BS EN 61008

• BS EN 61009

• BS EN 62423

• BS EN 60947-2

37. Providing necessary precautions are taken, a metallic pipe may be used as an earth electrode if it

• Carries flammable gases

• Is owned by a water utility company

• Is a private water supply pipe

• Is insulated