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Total questions: 39
Worksheet time: 24mins
Which type of earthing system relies on a separately supplied earth, usually the sheathing on the cable:
TT
TN-C-S
IT
TNS
Which of the following would not be one of the human senses to use during the initial verification of an addition to a lighting circuit:
Sight
Hearing
Taste
Touch
On a standard TT installation, the result of the resistance of the earth electrode and the rated RCD residual operating current should not exceed:
25v
50v
110v
400v
Which of the following protection devices is unlikely to be suited for short circuit currents in the region of 6kA:
BS 3036 semi-enclosed fuse
BS 88-3 cartridge fuse
BS 88-2 general purpose fuse
BS EN 60898 circuit breaker
Which of the following earthing systems has the path for earth leakage currents via the earth itself:
TN-S
TNC-S
TN-C
TT
A continuity test is to be carried out and the instrument has been confirmed as being in calibration and undamaged, Which of the following is the remaining check that needs to be carried out to confirm the instrument is suitable to use?
It is set to 230 V a.c
The battery is in a good condition
The leads comply with GS 38
It is set to read high values of resistance
Which of the following is the minimum short circuit test current for a low resistance ohmmeter?
50 mA
100 mA
200 mA
300 mA
During initial verification of a TN system the installation earth conductor was recorded as 16mm2. The minimum size of main bonding conductor should be:
4mm2
6 mm2
10 mm2
16 mm2
The purpose of the test button of a residual current device is to check the
Earth fault loop impedance
Continuity of the earthing conductor
Earth electrode resistance
Mechanical operation of the rcd
Which of the following is not the type of earthing :-
System Earthing
Equipment Earthing
earthing device
None
An electrical intake system which uses an earth rod would be classed as
TT
TN-S
TN-C-S
PME
An electrical intake system whereby the main earth conductor is connected to the sheath of the incoming supply cable is known as
TT
TN-S
TN-C-S
NC-S
The size of the main earthing conductor would typically be
6mm2
10mm2
12mm2
16mm2
The size of the main bonding conductor would typically be
4mm2
6mm2
10mm2
16mm2
Which one of the following tests should be carried out on the earthing circuit with the circuit live?
Earth Loop Impedance
Insulation Resistance
Earth Continuity
Polarity Test
The permanent inscribed notice on an earth bonding clip must read
safety electrical connection
safety electrical connection, do not remove
do not remove
safety electrical connection, replace after removal
Which one of the following supply systems would have three live conductors and a neutral?
4 phase
3 phase
2 phase
Single phase
When should a functional test be carried out?
While demonstrating the operation of an appliance to a customer
After the electrical system is energised
After handover of the system
Before any connections are made
The purpose of a polarity test is to verify which of the following?
MCBs, fuses and RCDs trip out in the correct time
Bonding is correctly installed
all fuses, switches and circuit breakers are connected in the line
Insulation is adequate
Which one of the following tests should be carried out on insulation?
Polarity
Resistance
Impedance
Continuity
When a polarity test is carried out, which instrument is used?
PAT tester
Proving unit
Low resistance ohmmeter
Earth loop impedance tester
In addition to main equipotential bonding of services within a building supplementary bonding may also be required where
metal pipes of different materials are used e.g. copper and steel
the different services enter the building at widely spaced points
plastic waste systems are used
metal pipework is jointed by plastic connectors
1. The weakest link in the circuit designed to break when an over current flows is one definition of:
A. Fault protection
A consumer unit
A fuse
A circuit protective conductor
A protective conductor connecting exposed and extraneous parts together is known as:
Earth electrode
Earthing conductor
Bonding conductor
Circuit protective conductor
What does the letter ‘C’ denote in a TNC-S earthing system?
Controlled
Confirmed
Combined
Concise
The only striped (2 colour) conductor used in fixed electrical installations is?
Three Phase
Neutral
Switch feed
Circuit protective conductor
The casing of 3 phase commercial water pump is called?
An exposed conductive part
An extraneous conductive part
An earthed arrangement
An earthed casing
The connection of the extraneous conductive parts in the installation to the main earthing terminal of the installation is one definition of?
Earth conductors
Exposed conductive parts
Protective equipotential bonding
Extraneous conductive parts
Which one of the following earthing arrangements is shown in the diagram?
TT
TN-S
TN-C
TN-C-S
