Fault Finding

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

Which of the following problems would not be classed as a transient fault

• overload

• lightning

• heavy current switching

• earth-fault voltages

The guidance for test leads used on instruments is contained in

• BS 7671

• EAWR

• HASAWA

• GS38

Which of the following documents is of least use when diagnosing faults?

• Schedule of test results

• Electrical Installation Certificate

• Installation specification

• Maintenance record

Which dead test would be carried out during intial fault diagnosis

• RCD test

• insulation resistance

• functional

• earth-fault loop impedance

On inspection of terminations at a motor, you observe conductor insulation has melted and discolouring of the terminal metal the most likely cause would be:

• overcurrent

• loose connection

• open circuit

• earth fault

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