Safety Alert 84 – Electric Shock (Neutral conductor back feed)

Date

15 April 2020

Description

The apprentice was tasked with replacing all light fittings in the outdoor veranda area of the weapons training facility at Irwin Barracks, Karrakatta. A Take 5 and JSA risk assessment were completed. After isolating the circuit, the tradesman and the apprentice acknowledged that the lighting turned off and then proceeded to tag out and test for power at one of the fittings.

After testing for power it was acknowledged that the circuit was dead (the apprentice confirmed isolation but with the tradesman’s voltstick and did not test on a known live source prior to testing the work area). The apprentice then started to remove the fitting and replaced with a new LED with no problems. He then proceeded to the second fitting to do the same. He realised that the loop-in-loop-out active and neutral would be too short to reach the terminal block of the new fitting, so he decided to cut the joint so it could be extended.

He cut the active conductors and the neutral conductors to separate the joint and and during the process he touched one of the active conductors and received an electric shock. The tradesman investigated what the apprentice had done and went to strip the cable that the apprentice had cut to test it and he also received and electric shock. Subsequent testing discovered that a neighbouring circuit had a neutral connected to the circuit they were working on and due to that circuit not being isolated, a potential difference existed between the separated cables.

Root Cause

1. Job/System Factors:

• Inadequate work procedures – the circuit affectively had two separate feeds (this work was carried out by a previous contractor – date/time unknown).
• Inadequate work procedures – the JSA in place only mentioned isolation, it did not detail the isolation process or procedure for identifying this type of fault.

1. Personal Factors:

• Improper motivation – when the apprentice parted the neutrals he did not re-test the circuit.

Contributing Factors

• Inadequate or improper protective equipment – the apprentice was not wearing protective gloves.
• Failure to follow procedures – when both the tradesman and apprentice parted the neutrals they did not re-test the circuit.

Recommendations

• Reaffirmation with the apprentice of the isolation procedure.
• EGT apprentices are to participate in the verification of de-energisation – testing to confirm an isolation should be completed by the Supervising Electrical Worker using an appropriate meter and witnessed by the apprentice. Apprentices should use their own voltstick where the work is being performed as a final personal safety check.
• The JSA in place is to detail the isolation procedure step-by-step.

Feedback

For further information regarding this Safety Alert, please contact EGT on (08) 6241 6100 or talk to your Field Officer.