Worker suffers electric shock forming concrete slab

The following article is a news item provided for the benefit of the Workplace Health and Safety profession. Its content does not necessarily reflect the views of the Australian Institute of Health & Safety.
Tuesday, 13 July, 2021 - 11:30
Incidents & prosecutions

A worker in Queensland recently received an electric shock while he was preparing to form up a concrete slab next to an existing structure.

Initial enquiries indicate he was using a sledgehammer to drive a star picket into the ground to support the wooden framework.

As he hammered the star picket into the ground it contacted an energised electric cable which gave him an electric shock.

While investigations are continuing, Workplace Health and Safety Queensland said in an incident alert that contact with underground electric lines can have deadly consequences.

Before carrying out ground-disturbing work, the alert said to consider whether underground essential services (including electric lines) could be present in the area. If they could, you should identify the risks and implement effective control measures associated with the work.

This includes complying with any requirements under relevant work health and safety and electrical safety legislation in relation to the work.

The best way of eliminating these hazards is to prevent people, plant, equipment and materials from coming close enough to contact electric lines.

Even if a line is de-energised, direct contact with it can still be dangerous, if nearby energised high voltage services are inducing a voltage onto it.

The alert said to develop a safe system of work for ground-disturbing work. This could include, but is not limited to the following examples:

  • If it is not known whether cables, conduits, apparatus or situations form an electrical safety risk, you should either assume that the risk exists, or have a qualified person investigate and report.
  • Obtain current information about underground essential services such as electricity, gas and telecommunications. ‘Dial Before You Dig’ is a free enquiry service for information on underground assets anywhere in Australia. ‘Dial Before You Dig’ will advise if electrical cables owned by one or more of its contributory members are located in the vicinity of your worksite.
  • Consult maps or talk to the property owner and electricity entities.
  • Conduct a site-specific risk assessment: think about where underground electric line pits are, inspection covers and building entry markers for underground services; what lies in a path between them; in what directions do cables or conduits leave these pits and therefore where are services most likely to be located.
  • Verify locations of underground services via non-ground-disturbing methods. For example, ground-penetrating radar or electromagnetic location. (Note: electromagnetic location will not find de-energised cables and ground-penetrating radar cannot distinguish between service types).
  • Pothole to confirm locations or service types definitively. Potholing involves digging with hand tools to a pre-determined depth to verify if assets exist in the immediate location. Insulated hand-digging tools suitable for the voltage concerned may be used. Vacuum extraction of potholes may also be used to locate underground cables.
  • Develop safe work practices and procedures and ensuring they are followed; safe work method statements are developed where required; and appropriately trained and qualified people are authorised to carry out the work
  • Develop control measures in consultation with workers performing specific tasks and consider the training they require or already have. Formal or on-the-job training may be appropriate depending on the circumstances.

Any remaining risk of live contact must also be minimised with suitable personal protective equipment, according to the alert, which said adopting and implementing higher-order controls, before considering administrative or PPE controls, will significantly reduce the likelihood of a similar incident occurring.