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WorksheetsElectrical Testing and Inspection 2
Total questions: 20
Worksheet time: 19mins
Given the following numbered tests, select the sequence in which these tests should be conducted for a new installation:- 1. functional 2. insulation resistance 3. polarity 4. continuity of final ring conductors 5. continuity of protective conductors:
1,3,4,5,2
4,5,3,2,1
5,4,2,3,1
2,3,4,5,1
Table 9A in the On Site Guide gives a value of 19.51 (mohm/m) for a line conductor of 2.5mm2 and a protective conductor of 1.5mm2. What would be the resistance of a circuit 25m in length when wired using these conductors:
4.87 ohm
487 ohm
780 ohm
0.487 ohm
Which of the following tests would be carried out 'live':
insulation resistance
earth continuity
prospective fault current
ring circuit continuity
An approved voltage tester can be used to:
Establish whether a circuit conductor is live or not
Determine the effectiveness of a disconnection device
Measure the resistance of an earth continuity conductor
Carry out continuity tests
Which of the following does not form part of the earth fault loop impedance
The phase conductor
The earth electrode
The cable armouring
The neutral within the consumer's installation
An earth fault loop impedance tester should only allow current to flow for:
0.4s
4.0s
40ms
400ms
A 100ma RCD protecting a TT installation tested at half the rated tripping current should
Not operate
Operate within 50ms
Operate within 100ms
Operate within 300ms
Which of the following requirements from GS 38 applies to test equipment which requires more than one test lead?
The leads must be at least 1m in length
The leads must have a csa of at least 1.5 mm2
The leads must be colour coded for identification
The leads must be permanently attached to the instrument
Which of the following correctly describes the purpose of a continuity of ring final circuit conductors test?
To confirm the conductors are installed as a complete ring
To confirm polarity is correct at each point on the circuit
To determine the R1+R2 value for the final circuit
To confirm the conductors are the correct csa
A test for continuity of circuit protective conductors is carried out at every point on a circuit. Which of the following describes the purpose of this test?
To confirm correct polarity
To confirm the conductors are correct csa
To determine the R1+R2 value for the circuit
To confirm exposed conductive parts are connected to the MET
Which of the following factors directly affects the conductor resistance of a cable?
Insulation and csa
Length and csa
Length and insulation
Load current and csa
Two identical cables are connected in parallel. Which of the following describes the effect on the combined conductor resistance compared to the single cable?
Doubled
Quartered
Halved
No effect
Which of the following factors affect the insulation resistance of a cable?
Conductor cross-sectional area
Cable length
Installation method
Load current
Four identical circuits are connected to a distribution board. Which of the following describes the effect on the combined insulation resistance at the DB when compared to that of a single circuit?
Doubled
Quartered
Halved
No effect
Control gear and interlocks should be operated when carrying out:
Functional testing
Isolation testing
Polarity testing
Continuity testing
Four circuits have insulation resistances of 20 Mohm, 25 Mohm, 40 Mohm and 50 Mohm. When tested together (insulation lump test) what would be the expected reading:
0.135 Mohm
6.5 Mohm
7.4 Mohm
13.5 Mohm
Which of the following should accompany the inspection and test certificate:
Two copies of test results
Copies of the inspection and test schedules
Copies of minor works certificates
Invoices for any remedial work carried out
A 230V single phase circuit supplies a light which is controlled by a passive infra red sensor. Special care must be taken before insulation resistance testing is carried out because the test may:
Cause the circuit breaker to trip
Operate the sensor and damage the light
Permanently damage the sensor
Give a false reading
Which of the following is not an example of an 'essential test' when carrying out minor works:
Prospective fault current
Earth fault loop impedance
Insulation resistance
Polarity
Digital test instruments should have an accuracy, as stated in GN3, of what percentage of full scale deflection (fsd):
1%
3%
5%
7%
