Live sub-surface power cable inadvertently cut

Trenching activities for the onshore pipeline installation were being completed. During the trenching works, the excavator operator inadvertently cut into an energised three-phase 21.6kVA power cable buried at approximately 2 metres.

Upon finding the cable an “All Stop” was called, personnel immediately evacuated from the immediate area, and the area of works secured.  Company management and the client were informed. There were no injuries to personnel nor damage to excavating equipment.

The client subsequently de-energised the power to ensure the cable was no longer “live”, and a registered electrician then repaired the cable and brought the cable back into service.

Our member noted the following issues:

• Work Planning
  • The cable had been installed two years before by the client’s subcontractor, before our member was involved.
  • Investigation found that the cable was not reported on the initial as-built report.
  • Review of client-supplied drawings found that the power cable was noted as a ‘future cable’; and should not have been in its as-found location.
• Control of Work
  • The cable was live with no isolation in place.
  • During the excavation works there was a spotter in place but there was no expectation of finding a cable.
• Risk Assessment
  • During the risk assessment process covering the excavation and trenching work, this cable hazard was not identified, and therefore a cable tracker application was not included as a key control measure.