Fault finding NETK3/7

An operative carrying out fault diagnosis would not need to be familiar with:

• supply earthing system

• schedule of test results

• repair cost

• voltage present

Which of the following would not be required in a fault finding sequence:

• time repair will take

• safe isolation

• testing

• analysis of results

A continuity test as part of fault diagnosis would be carried out with which instrument:

• earth-fault loop impedance tester

• high resistance ohmmeter

• low resistance ohmmeter

• RCD tester

A loose termination could cause the following

• short circuit between live conductors

• overcurrent

• arcing

• operation of the protective device

The guidance for test leads used on instruments is contained in

• BS 7671

• EAWR

• HASAWA

• GS38

Which dead test would be carried out during intial fault diagnosis

• RCD test

• insulation resistance

• functional

• earth-fault loop impedance

Whilst fault finding you check and discover the BS 3036 fuse protecting the circuit has ruptured with globules of copper spattered over the holder together with black carbon powder. The most likely fault would be:

• short circuit

• open circuit

• loose termination

• broken conductor

Whilst fault finding, you check and discover the BS 3036 fuse protecting the circuit has melted in the middle only. The most likely fault would be:

• open circuit

• short circuit

• loose termination

• overload

A result of >100Ω on a continuity test would indicate what type of fault:

• none

• an insulation failure

• open circuit

• short circuit

An RCD would protect against the following fault:

• open circuit

• overcurrent

• short circuit between live conductors

• short circuit between live conductors and earth