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Person electrocuted digging trench

In May 2023, a person was electrocuted while attempting to repair a water leak in an underground pipe. Early enquiries indicated that the person unearthed a black poly water pipe believed to be the water pipe that required repair, and then cut into it using conduit shears.

While cutting the poly pipe, it appears the shears contacted the energised cable within resulting in the person receiving a fatal electric shock.

This incident is a reminder that electrical cables may not always be correctly installed underground in orange electrical conduit or be compliant to installation safety standards.

Investigations are continuing.

Safety issues

Electrical risks are ever present and not always obvious.

Before you dig:

  • Be aware that electric cables can be difficult to identify as sometimes they may be encased in other materials like concrete, steel, or plastic pipe.
  • Look for the presence of underground electrical cables supplying buildings from the street or between buildings or to sheds, pools, garden lights, pumps etc.
  • Look for other signs of underground electric cables such as conduits and pipes on walls leading to the ground.
  • Look for changes in ground level over time such as ground levelling which might reduce the depth you expect underground electrical cables to be located.
  • A voltage proximity detector, (non-contact voltage checker) will provide an indication if voltages are present when dealing with underground pipes (for most situations).

Whether you are involved in large-scale trenching and construction works, vertical or horizontal boring, digging a hole, or driving a star picket into the ground, contact with underground electrical cables can have deadly consequences. The most common electrical risks and causes of injury associated with working near underground electric lines are:

  • electric shock
  • arcing, explosion, or fire (arcing or explosion can occur when high fault currents are present)
  • electric shock from ‘step-and-touch’ potentials.

Examples of work that involves risk of contact with energised underground electric lines can include:

  • excavating a trench
  • digging fencing holes
  • driving posts or pegs.

Ways to manage health and safety

Effective risk management starts with a commitment to health and safety from those who manage the business. If an incident occurs, you'll need to show the regulator that you’ve used an effective risk management process. This responsibility is covered by your primary duty of care in the Work Health and Safety Act 2011 and Electrical Safety Act 2002.

Use the hierarchy of controls to help decide how to eliminate and reduce risks in your place of work. The hierarchy of controls ranks types of control methods from the highest level of protection and reliability to the lowest. It’s a step-by-step approach to eliminating or reducing risks. You must work through the hierarchy of controls when managing risks, with the aim of eliminating the hazard, which is the most effective control.

Possible control measures to prevent similar incidents

A person conducting a business or undertaking at a workplace must ensure no person, plant or thing at the workplace comes within an unsafe distance of an overhead powerline or underground cable.

Before carrying out ground-disturbing work, 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 (e.g., WHS Regulation 2011 - Excavation work—underground essential services).

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 into it. Methods to eliminate potential contact with an electrical line may include:

  • relocating the digging work away from underground services; if possible
  • de-energising and isolating the electric line for the duration of work. In some situations, earthing the line would also be necessary, especially if near high voltage services
  • re-routing the electric line away from the work area.

A safe system of work should also be implemented to manage the risks of coming within an unsafe distance of an underground electric line which includes planning your work in advance. When developing a safe system of work, you should consider the following.

Before excavation starts, identify all underground services:

  • Visit Before You Dig Australia (BYDA) for information about underground essential services at near where the excavation is to be done (this service excludes private property).
  • Research and comply with your electricity distributor requirements.
  • Contact the property owner for information on underground services (plans, service types and locations). Do not make assumptions when locating any foreign underground poly piping system as it may be used as a protective layer for other means (such as electrical wiring, data cabling etc.).
  • Use electronic locating instruments to establish approximate locations (plans and/or electronic service location, cannot be relied upon for physical service locations) and non-mechanical excavation must occur to determine exact locations.
  • 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.
  • Conduct a site-specific risk assessment: think about where underground electric line pits are, inspection covers, and building entry markers for underground services. Consider also, what lies in a path between them, in what directions do cables or conduits leave these pits, and therefore, where services are most likely to be located.
  • Use advice about underground electrical cables, such as location, type, depth, and work restrictions, to excavate safely.

When conducting excavation works:

  • Visually locate cables by potholing using non-mechanical excavation (hydrovac or non-conductive hand tools) to prove the exact location.
  • Watch out for warning signs of underground electrical cables such as orange tape, conduits, sand, or other markers.
  • Be aware underground electrical cables and conduits may not be at the original depth because of changes in ground levels.
  • If you encounter or contact an underground electrical cable, don’t move it (contact your electricity distributor or electrical contractor immediately and follow their advice).
  • The person with control of the workplace must ensure advice about the location of underground electrical cables is given to all engaged to carry out the excavation.

Information training and instruction:

  • Developing safe work practices and procedures and ensuring they are followed; safe work method statements (SWMS) are developed where required, and appropriately trained and qualified people are authorised to carry out the work.
  • Developing control measures in consultation with workers performing specific tasks and consider any training they require or already have. Formal or on-the-job training may be appropriate depending on the circumstances. Examples include:
    • induction training - to ensure new starters or workers new to a job are trained on safe systems of work and other relevant health and safety matters.
    • supervisor and management training – to ensure that safety issues are appropriately managed at the workplace.
    • work specific training - to ensure that workers carrying out particular work are trained on any electrical and other risks specific to the work, as appropriate.
    • emergency procedure training - to ensure workers know what to do in the event of an emergency, (e.g., procedures to follow if a person receives an electric shock).
    • first aid training —to ensure appropriate procedures are followed for administering first aid, (e.g., proper treatment for electric shock).

Any remaining risk must be minimised with suitable personal protective equipment. For example:

  • electrical insulating gloves which have been electrically tested in accordance with Australian Standards.
  • rubber soled boots.
  • standing on a rubber insulating mat.
  • standing on an equipotential conductive mat.

Adopting and implementing higher order controls, before considering administrative or PPE controls, will significantly reduce the likelihood of a similar incident occurring. The control measures you put in place should be reviewed regularly to make sure they work as planned.

More information

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Last updated 29 November 2023