Worksheets18 Edition Part 5 (a)
Total questions: 20
Worksheet time: 40mins
Which one of the following devices would not be suitable for use as a circuit isolator? Mark one answer
A. A contactor
B. A device with semiconductors
C. A fuse
D. An RCD
Wiring systems shall be selected and erected so as to be suitable for?
The highest and lowest local ambient temperature
The maximum ambient temperature
The maximum and minimum conductor temperature
The maximum conductor temperature
Type 1 SPD's (Surge Protection Devices) are often referred to as?
Earth bonding SPD's
Equipotential bonding SPD's
Exposed conductive SPD's
Extraneous conductive SPD's
An item of switchgear is installed behind a fixed panel thus making the operation of the switchgear impossible for the operator to observe. In such situations a suitable indicator must be fixed in a position where the operator can see the effect of the operation, the indicator must comply with?
BS EN 12954
BS EN 3535
BS EN 4444 or BS EN 6346
BS EN 60073 and BS EN 60447
All outdoor lighting installations need to be carefully selected and erected, but which type of lighting is excluded from BS 7671? Mark one answer
Advertising signs
Festoon lighting that is temporary
Phone kiosks
Road lighting
What is the maximum operating temperature for thermosetting cables?
105°C
70°C
80°C
90°C
What type of circuits do the images below represent? Mark one answer
Auxiliary circuits
Generator control circuits
IT systems
Safety services circuits
In an electrical circuit, a junction box complying with BS 5733 need not be accessible for inspection, testing and maintenance if it bears the symbol?
A
C
D
If the cross-sectional-area (c.s.a) of the supply PEN conductor where PME applies is 100 mm², what is the minimum size the main protective bonding conductor can be? Mark one answer
16 mm²
25 mm²
35 mm²
50 mm²
A PEN conductor when insulated can use the following insulation colour? Mark one answer
A Blue only
B Green only
C Green-and-Yellow only
D Green-and-Yellow throughout its length with blue markings at the terminations
An automatic electrical safety supply with a maximum changeover time of 3.5 seconds is classified as a?
Long break
Medium break
Normal break
Short break
What does the external influence code AH3 represent?
High severity vibration
Low severity vibration
Medium severity vibration
Very low severity vibration
Where it is desired NOT to calculate the sizing of a cpc, we can use the alternative method to Regulation 543.1.3 for sizing a cpc. What is the minimum size cpc to be used when a copper line conductor has a cross-sectional area (c.s.a) of 95 mm² and it is desired to have the cpc also made from copper?
16 mm²
25 mm²
35 mm²
50 mm²
A three-phase supply that is expected to draw a heavy current is to be installed in a ferrous metal distribution board. The supply cables will comprise of three single-core insulated a.c. cables. What precautions must be taken to prevent eddy currents circulating in the ferrous distribution board material between the conductors? Mark one answer
A Bond all cable glands
B Connect all three conductors together
C Replace the ferrous material with non-ferrous at the point of entry
D Use rubber grommets between the cables and the metal enclosure
Is it permissible to install an electric cable at the top of a plaster covered wall at a depth of less than 50 mm from the plaster surface, without any form of earthed mechanical protection?
No this is not permitted in any circumstance
Yes, if a 100 mA RCD is fitted in the main switch of the consumer unit
Yes, if the cable is installed within 150 mm from the top of the wall and a 30 mA RCD is protecting the circuit
Yes, if the circuit is supplied from a safety source
A client requires a lighting system to be installed in a 'pelmet', with regards to this type of installation BS 7671 stipulates that "There shall be"?
No adverse effects due to the presence of curtains
No adverse effects due to the presence of heat
No adverse effects due to the presence of sunlight
No adverse effects due to the presence of wall-paper
Where identification of individual conductors is made by use of numerals, what colour ratio is permitted for the identification?
A Black on Brown
B Black on White
C Red on Black
D Yellow on Brown
A generating set is to run in parallel with the public supply system, which of the following factors need NOT be taken into consideration? Mark one answer
Earth fault loop impedance
Harmonic distortion
Power factor
Voltage changes
Where water may collect or condensation may form in a wiring system, provision shall be made for?
Effects of corrosion
Its escape
Short circuits
Ventilation
What specific function can an electrical device provide, if the symbol shown below is marked on the device?
All the above
Emergency switching
Functional switching
Isolation
