Workers using a grinder to remove a redundant conveyor inadvertently cut into a live electrical cable after they incorrectly assumed that all nearby cables had been de-energised.
The electrical supervisor had confirmed to the workers that the conveyor motor was redundant and its electrical cables were safe to cut. However, the workers mistakenly thought that other nearby cables were also redundant and de-energised.
Findings
The cut electrical cable was not part of the redundant conveyor and was still live, posing a serious risk of electric shock, arc flash or electrocution. The incident did not result in any injuries, but it highlighted critical failures in electrical isolation, verification and supervision.
Takeaways
- A qualified person must test and verify that all electrical components are de-energised before work begins on equipment.
- Electrical supervisors must consider the complexities of tasks and the capabilities of workers when they are assigning jobs involving electrical cables or exposed electrical equipment.
- Sites should involve electrical supervisors in all high-risk work assessments, and all job hazard/safety analysis processes should include electrical verification and isolation steps.
- In Western Australia, the Electricity (Licensing) Regulations 1991, the Work Health and Safety (Mines) Regulations 2022 and several Australian Standards, including AS/NZS 3000:2018 (Electrical installations, known as the Wiring Rules) and AS/NZS 4836:2023 (Safe working on or near low-voltage electrical installations and equipment), govern electrical isolation requirements.
Summary
Workers must treat all electrical work as live work until proven otherwise. Assumptions can lead to catastrophic work health and safety consequences. Isolation, testing and supervision are essential controls to prevent serious injuries or deaths.
