In November 2017, an electrical installation was de-energised in preparation for the disconnection of temporary power cables and reconnection of permanent power cables at a facility’s electrical distribution boards.
During the works, an electrician received an electric shock when he inadvertently created a ‘floating neutral’ situation.
Work was suspended and the electrician was taken to hospital for a precautionary electro-cardiograph (ECG) before being cleared to return to work.
Immediately after the incident, voltage measurements were taken between earth and neutral terminals in the distribution board which indicated a voltage of 87 V AC.
The following procedural controls were in place at the time of the incident:
- the operator’s permit to work (PTW) system was followed, including review of the single line diagrams
- an isolation list was finalised and isolations in the field were completed, which included independent verification of the isolations
- a ‘test for dead’ (zero volt test) was performed at the distribution boards by the electrician, and a zero volt reading was witnessed by all personnel involved in the task.
Further information
- Department of Energy, Mines, Industry Regulation and Safety
- Guidance about the isolation of hazardous energies
- Isolation of hazardous energies associated with plant in Western Australian mining operations guideline
- Standards Australia, www.standards.org.au
AS/NZS 3000 Electrical installations (the Australian/New Zealand wiring rules)