WorksheetsElectrical Fault Finding A
Total questions: 20
Worksheet time: 10mins
An approved voltage indicator should be used to
Measure R1+R2
Prove a circuit is dead before work begins
Measure appropriate voltage
Prove a circuit is live before work begins
The definition of isolation is
Functional switching for normal operation
Single pole devices connected in the phase conductor
Removing from every source of electrical energy
Isolating equipment from general mass of earth
The item shown in the photo should be used in what process?
Voltage measurement
Socket polarity
Calibration checks
Safe isolation
Which of the following is the most likely of implications caused from an exposed terminal?
Electric shock to a person or livestock
MCB operate
RCD Operates
Main Cut off fuse operates
When working on a circuit supplied by a fuse, which of the following methods is the LEAST acceptable method of ensuring accidental re-energisation?
The gap should be covered by bright insulation tape
A lockable fuse insert is put in its place
The lid of the consumer unit is locked
A dummy fuse carrier should be placed in place
The safest method of ensuring that a system is safe to work on is?
Follow the safe isolation procedure
Isolate the installation at the main cut-out
Use a fluke volt stick before you begin
Place barriers at the distribution boards
What is the benefit of using multi-hasp type padlock when isolating and locking off a circuit for maintenance?
More than one circuit can be isolated at any one time
Any single operative can make the circuit live once they have completed their task
A circuit can only be made dead if all the operatives use locks
More than one person can work on the circuit safely
Which of the following is the most likely of implications caused from fault diagnostics
Arcing
Open circuit
Loss of power
Short circuit
Which of the following would be most important to be discussed with the client prior to any fault diagnostics being carried out.
Cost of the work
Isolation timing
The Earthing system
The breaking capacity of the main protective device
Which of the following could cause an SPD to operate
Short circuit
Lightning stikes in the area
Overload in the circuit
A damaged light switch
Which of the following could cause an SPD to operate
Short circuit
Overload in the circuit
Switching of large induction motors
A damaged lamp
Which of the following would be the most likely cause of the final light in a lighting circuit not working when the other lights do
Short Circuit at the origin
Open Circuit at the origin
Open circuit in the last leg of the cable
Short Circuit in the last leg of the cable
If equipment plugged into a socket outlet is not working which of the following is the likely cause
Loose Earth cable
Faulty Switch
Earth leakage
One of the Line conductors has become loose
Which of the following is likely to cause a transient voltage spike
Switching surge from large induction motors
High resistance joint
Short Circuit
Earth fault
Which of the following would most likely cause a motor to not work if the circuit is healthy
High resistance joint in the isolator
Equipment malfunction
Too many capacitors causing a leading effect
Lightning strike
Which logical stage should be carried first before carrying out fault diagnosis
Gather information on Symptoms
Rectify the work
Safe isolation
Functional testing
To maintain accurate readings, an instrument should
Have its batteries replaced frequently
Be checked annually against national standards
Be checked against similar instruments
Be checked daily for any wear or tear
Which of the following tests is performed if a broken cable is suspected?
Prospective Fault Current
Insulation Resistance
Continuity of Ring Final Conductors
Earth Fault Loop Impedance
Several test instruments are used on an installation, which of the following would be most likely to give a reading of 2.5kA?
Low resistance ohmmeter
Prospective fault current
Insulation resistance tester
RCD tester
The main reason for the cross connecting the conductors during the ring final circuit test and not just relying on end to end reading is?
To record the values in the R1+R2 box at the same time
A more accurate R2 reading can be obtained
To ensure that the circuit is clear of short circuits or earth faults
To detect any interconnections in the circuit
