Worksheets18th Edition Part 5 b
Total questions: 35
Worksheet time: 18mins
A circuit is installed with 10 mm² 70°C thermoplastic multicore cable which has a protective conductor made of copper. The maximum fault current that can occur in the circuit is 600 amps, which will disconnect the circuit in 0.1 seconds, what is the minimum acceptable cross-sectional area of the cpc? Mark one answer
1.0 mm²
1.5 mm²
2.5 mm²
4.0 mm²
What is the minimum allowable size of copper cable used for a main protective bonding conductor?
1 mm²
25 mm²
35 mm²
6 mm²
Where a private source for a safety service can operate in parallel with the public supply systems, permission to operate the source must be obtained from?
The distribution network operator (DNO)
The duty-holder
The health and safety executive
The installation designer
Three circuits can share the same ducting system, provided?
Every cable is insulated to the highest voltage present
Only plastic ducting is used
The cables are separated by 500 mm
The ducting has partitions
An installation includes a d.c. power circuit with a grey coloured cable, which terminal does this cable connect to? Mark one answer
A Earth
B Mid-wire
C Negative
D Positive
A powertrack system shall be installed in accordance with the manufactures instructions, taking into account?
The external influences
The maximum prospective fault current of the conductors
The maximum temperature rating of the track
The number of bunched circuits
An RCD is to be used to provide protection against electric shock, the RCD shall be capable of disconnecting?
The cpc
The line conductors
The live conductors
The neutral conductor
It can be considered that the neutral conductor may carry a significant electric current in a three-phase system when a third harmonic current is present with a harmonic distortion greater than?
0.01
0.05
0.1
0.15
What is the minimum cross-sectional area of an unscreened multi-core copper conductor used for data transfer?
0.1 mm²
0.2 mm²
0.4 mm²
0.5 mm²
Where does it state they should be red?
511.2
537.3.3.5
541.3
560.9
When a ceiling rose is fitted in a lighting circuit it shall comply with?
BS 67
BS 6972
BS EN 60309-2
BS EN 60598
Which one of these is not a recognised power source for a generating set? Mark one answer
Combustion engine
Electric motor
Electrochemical accumulator
The public mains supply
The presence of a SPD (Surge Protection Device) installed downstream of a distribution board shall be indicated by? Mark one answer
A. A warning label attached on or near the distribution board
B. A warning neon on the distribution board
C. A warning neon on the socket-outlet
D. Yellow socket-outlets on the protected circuit
A wiring system is installed on a river wall where it may be subject to 'waves' the external influence code is?
AA3
AB4
AC5
AD6
Which of the following may not be used as a protective conductor? Mark one answer
A conductor in a cable
A fixed bare conductor
A gas pipe
A single-core cable
Which of the following devices would not be suitable for switching of a circuit for maintenance purposes? Mark one answer
Circuit breaker to BS EN 60898
Fuse to BS 88
Plug and switched socket outlet to BS 1363-1
RCD to BS EN 60947-2
Safety sources for safety services need to be installed?
As fixed equipment
As removable equipment
Higher than 2.5 above ground
More than 100m from the installation
As an apprentice electrician you were taught that all electrical wiring shall be marked so it can be easily identified for inspection, testing, or maintenance, but which regulation in BS 7671 states this must be so?
A 511.1
B 512.2
C 514.1.2
D 515.2
A semi-enclosed fuse has blown. The fuse is rated at 30A, what size wire should be used to repair the fuse? Mark one answer
A 0.75mm
B 0.85 mm
C 1.25mm
D 1.53mm
Where very fine multicore wire conductors are used in a circuit which will be terminated with screw terminals, in order to prevent unwanted separation or spreading of individual wires, which of the following method may be used? Mark one answer
Soldering (tinning) a length at least 10mm at the end of the multi-wire
Soldering (tinning) a length at least 5mm at the end of the multi-wire
Soldering (tinning) the whole conductor end of the multi-wire
Suitable terminals
When selecting an a.c. wiring system, which one of these cable types shall NOT be used? Mark one answer
A MICC
B SWA multi-core
C SWA single core
D T&E
A cross-sectional area increase in the size of the neutral conductor may be required when the total harmonic content due to triplen harmonic currents is greater than?
24%
27%
30%
33%
Where stationary batteries are installed to provide additional means of power in the event of failure of the public supply system, precautions must be taken to prevent inadvertently touching simultaneous conductive parts with a potential difference exceeding?
120 volts
50 volts
55 volts
60 volts
The external influence code 'AN' refers to?
The presence of fauna
The presence of mould or growth
The presence of seismic events
The presence of solar and ultraviolet radiation
What is the k value where steel conduit is used as the protective conductor for 90°C thermosetting cables?
A 44
B 47
C 58
D 143
For a simple installation a legible diagram indicating the size of conductors must be provided unless?
A schedule is provided
The client does not request it
The information is not available
The installer cannot draw
A lighting circuit fitted with an E14 type lampholder must be protected by an overcurrent protective device, of maximum rating?
A 10 amps
B 10 amps
C 16 amps
D 5 amps
What is the maximum operating temperature for mineral insulated cables, which are not thermoplastic covered and not exposed to touch?
105°C
70°C
80°C
90°C
The minimum cross-sectional area of a buried copper earthing conductor that is not protected against corrosion and not protected against mechanical damage is?
15 mm²
20 mm²
25 mm²
50 mm²
Where may the conductor insulation colour 'Green' be used for live conductors, protective conductors, or functional earthing and bonding conductors?
Never
Only as the protective conductor is safety circuits
Only in a hospital operating theatre on an IT system
Only where a fire-fighters switch is used
If the nominal voltage between the line conductor and the neutral conductor in a TN 230/400 V system is 230 volts what is the maximum continuous operating voltage Uc of a SPD (Surge Protection Device)?
A 415 volts
B 420 volts
C 430 volts
D 440 volts
Where a wiring system may be subject to 'a significant quantity of dust' the external influence code is?
AC2
AD3
AE4
AF5
Where can further information on emergency escape lighting be found?
A BS 5266
B BS 5839
C BS 88
D BS EN 60898
Insulation monitoring devices for use in IT systems shall be designed or installed so that it is only possible to modify the setting by?
The skilled electrician
The system designer
The use of a key or tool
The user of the installation
A step-up auto-transformer must not be connected to what type of system? Mark one answer
A IT
B TN-C-S
C TN-S
D TT
