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Worksheets2391 Inspection & Testing Questions
Total questions: 40
Worksheet time: 1hrs 5mins
OSG gives the maximum stable value of Ze for a TT installation as:
1660 ohms
600 ohms
200 ohms
100 ohms
Which type of earthing system relies on a separately supplied earth, usually the sheathing on the cable?
TT
TN-C-S
IT
TN-S
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
The term given to the person responsible for an electrical system is the:
Competent person
Electrician
Duty holder
Company manager
Regional electricity companies quote a maximum likely value of external loop impedance (outside the consumer's installation) for a TN-S system as:
0.35 ohm
0.8 ohm
21 ohm
200 ohm
EAWR states that working live is acceptable unless:
Suitable tools are used
Suitable PPE is worn
It is reasonable in all circumstances for it to be dead
An engineer gives you permission
Overloaded windings on a 3 phase motor may be identified in the first instance by using which sense:
Sight
Smell
Touch
Taste
Which of the following earthing systems has the path for earth leakage currents via the earth itself:
TN-S
TNC-S
TN-C
TT
Which of the following is the correct voltage for carrying out an insulation resistance test on a 400V three-phase circuit terminated at an isolator?
250 V
400 V
500 V
1000 V
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?
Check the battery level
Verify the test leads
Inspect the display screen
Ensure the correct settings are selected
Which of the following is the minimum short circuit test current for a low resistance ohmmeter?
50 mA
100 mA
200 mA
300 mA
In addition to calibration which of the following should be carried out and recorded?
Regular conformation of the instrument`s compliance with BS 7671
Extension of the instrument warranty period
Regular instrument accuracy checks
Closed circuit voltage checks
Which of the following is the maximum voltage above which test leads must comply with the requirements of GS 38?
25 V a.c.
25 V d.c.
50 V a.c.
50 V d.c.
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
Which of the following is not permitted for use as an earth electrode:
Underground structural metalwork
Metal water mains pipes
Lead sheaths of cables
Earth plates
Which one of the following does not need to be checked for compliance during the visual inspection of an installation:
presence of fire barriers
correct connection of the supply authority's fuse
routing of cables in safe zones
connection of single pole devices in line conductors only
End-to-end resistance checks would be carried out on a:
radial circuit
lighting circuit
ring final circuit
fused connection unit
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
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
A Megger Test
Functional testing
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
What is 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 M ohm, 25 M ohm, 40 M ohm and 50 M ohm. When tested together (insulation test) what would be the expected reading:
0.135 M ohm
6.5 M ohm
7.4 M ohm
13.5 M ohm
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
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%
What type of certificate is issued after a rewire of a domestic property?
Minor works certificate
Schedule of test results
Electrical Installation Certificate
Domestic Installation Certificate
