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- 1. Multiple Choice
The accessory pictured is often used in testing when conducting test using what particular method?
Test method 2
Test method 1
Continuity of ring final conductors
Test method 3
- 2. Multiple Choice
The Ze is to be measured as part of the initial verification process, what instrument should be used for this task?
An earth fault loop impedance tester
An insulation resistance tester
An RCD tester
A low resistance ohmmeter
- 3. Multiple Choice
The maximum value of earth electrode resistance for a TT installation protected by a 500mA RCD is given by BS7671 as
1660Ω
500Ω
160Ω
100 Ω
- 4. Multiple Choice
A 100mA RCD protecting a TT installation tested at 1/2 I should
Operate within 300ms
Operate within 200ms
Not operate
Operate within 40ms
- 5. Multiple Choice
The following readings were taken on a test performed on a ring final circuit, Line to Line 0.8 Ω Neutral to Neutral 0.8 Ω cpc to cpc 0.8 Ω . What would be the expected reading between line and cpc at each socket outlet?
1.6 Ω
0.4 Ω
0.8 Ω
0.2 Ω
- 6. Multiple Choice
What is the importance of verifying readings obtained with those listed within BS7671 and associated documents?
The circuit is safe and within design parameters
The circuit protection does not operate accidentally without warning
The instrument is functioning correctly and within stated tolerances
The instrument conforms to BS EN 61010
- 7. Multiple Choice
If two bonding conductors or equal length were connected in parallel the resistance would
Increase
Double
Not change
Halve
- 8. Multiple Choice
During a continuity of Ring final conductors test, 10 Sockets give a R1+R2 reading of 0.68 Ω, but one socket gives a reading of 0.92 Ω. What might that indicate?
A spur on the circuit
A trapped cpc in the back of the box
A short circuit
A high resistance fault
- 9. Multiple Choice
A polarity test is conducted to verify that
There is no breakdown of the insulation of the conductor
The resistance is sufficiently low to operate the protective device within the specified time
The circuit protection will operate within a pre-determined time
Every protective and single pole device is connected in the line conductor only
- 10. Multiple Choice
If 3 conductors equal in length and with a resistance of 1.5 Ω are connected in parallel, what is the total resistance?
4.5 Ω
0.5 Ω
2 Ω
15 Ω
- 11. Multiple Choice
A test of continuity at each socket-outlet or a ring final circuit is carried out to ensure that
The polarity of sockets is correct
All cables are of the same construction
The ring has not been interconnected
All cables are of the same size
- 12. Multiple Choice
If a copper conductor was doubled in length, the resistance would
Halve
Double
Stay the same
Quadruple
- 13. Multiple Choice
Given that 1.5mm2 cable has a resistance per metre of 12.1millohms, how long approximately would a length of cpc be to give a reading 0.36 Ω ?
40m
30m
10m
20m
- 14. Multiple Choice
What is the formula for calculating earth fault loop impedance?
Zs = Ze-(R1+R2)
Zs = Ze+(R1+R2)
Ze = Zs-(R1+R2)
Zs = Zex(R1+R2)
- 15. Multiple Choice
An RCD within a domestic is tripping intermittently, the most likely cause for this will be,
a faulty appliance that is still plugged in
a short circuit fault
an overload
a transient voltage
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