18th Edition Part 4 Mock 3

In an electrical substation supplying an IT system, the power frequency stress voltages, with RE and RA interconnected and an existing earth fault in the installation, the value of U1 is equal to?

• a)       Uo
• b)           Uo x 3
• c)             RA x Id
• d)       RAXIE+Uox 3

Which of these is not an example of an extraneous-conductive part?

• a)       Central heating radiator
• b)       Gas installation pipe
• c)        Air conditioning duct
• d)       PVC conduit system

Which of the following would allow the omission of fault protection?

• a)       Unearthed street furniture supplied from an overhead line and inaccessible in normal use
• b)        Large exposed conductive parts
• c)        Concrete poles where the steel reinforcement is above the surface
• d)        A non-conducting location under skilled supervision

In a TN system connected to the public supply, who is responsible for the integrity of a PEN conductors' connection to earth, external to the installation?

• a)    The installer
• b)     A skilled competent person
• c)     The inspector
• d)    The distributor

What is the maximum earth fault loop impedance Zs for a 13A, BS 1362 fuse to ensure a 0.4s disconnection time?

• a) 23.2 Q
• b) 3.83 Q
• c) 16.4 Q
• d) 2.3 Q

Q14) In locations where BE2 conditions exist and, unless otherwise recommended by equipment manufacturers, what is the maximum rating of a projector lamp that is positioned 0.8 m from combustible material?

• a)         100 W
• b)        200 W
• c)         300 W
• d)         400 W

Which of the following is an example of an extraneous-conductive part?

• a)        Metal water installation pipe
• b)        Non-metallic water pipe in a bathroom
• c)        Metallic girder work totally embedded in the fabric of the building
• d)        Polyvinyl chloride (PVC) conduit system

Where protection against overcurrent is being considered in a TN or TT system, the neutral conductor shall be protected against?

• a)        RCD tripping
• b)        Short circuit current
• c)         Harmonic currents
• d)        Open-circuit faults

Exposed-conductive parts, which are simultaneously accessible, shall be connected to the same earthing system?

• a)        In groups
• b)         Via a high-ohmic resistance
• c)         Through a conduit system
• d)        Never

Q18) Where different buildings have separate equipotential bonding systems, which may cause electromagnetic disturbances, which of the following system is not preferred for signal and data transmission?

• a)         Microwave signal
• b)        Optical fibres
• c)         Laser transmission signal
• d)        Copper wire