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WorksheetsL3 Electrical - Earthing, Safety & Testing
Total questions: 20
Worksheet time: 10mins
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 earthing system whereby the neutral combines the function of both neutral and earth is termed
TN-S
TT-S
TN-C-S
NE-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
A test current of 150mA should cause a 30mA RCD to trip out in which of the times listed below?
0.4 seconds
40 milliseconds
4 seconds
4 milliseconds
The main use of a 30mA RCD is to provide which of following?
Additional protection
Protection against overloading
A test point for instruments
Protection against older wiring
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
All electrical testing equipment should comply with which document
GS 38
The Electricity at work Regulations
BS 7671
Part P
The test probes on leads used with electrical test equipment must be insulated and with exposed metal tips not exceeding
2mm
4mm
4mm but 2mm strongly recommended
only spring loaded retractable screened probes to be used
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
Which of the British standards listed below is also known as the IET Wiring Regulations?
GS 38
BS 7671
BS 6717
BS 6700
Which test can confirm that the circuit disconnection times can be met?
Polarity
Earth continuity
Earth fault loop impedance
Insulation resistance
When a polarity test is carried out, which instrument is used?
PAT tester
Proving unit
Low resistance ohmmeter
Earth loop impedance tester
As well as a proving unit, which one of the following is also used to check if a circuit is dead?
Approved multi-meter
Approved test lamp
Approved voltage indicator
Approved fuse 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
