The purpose of this alert is to remind people of the inherent dangers of cutting electrical conduits that are in service. These conduits may contain multiple circuits.

Background

We recently responded to an incident where an electrical contractor received a fatal electric shock. The contractor was replacing a faulty lighting circuit that was located in an underground heavy duty PVC conduit. He isolated the lighting circuit at the meter board and proceeded to carry out the repairs.

The replacement cable that was being pulled through the underground conduit became stuck. The contractor then dug a trench to expose a section of the conduit and proceeded to cut through it using conduit cutters.

When cutting the conduit, the contractor struck an energised 415 volt three phase sub-main circuit that was located in the same underground conduit as the 240 volt lighting circuit he was working on.

Image shows multiple separate circuits within the conduit

Contributing factors

Investigations are continuing; however, a number of factors contributed to the incident:

  • Insufficient planning and assessment for the job.
  • Failure to identify all contents of the underground PVC conduit being worked on.
  • Failure to isolate power to the premises at the main switch.

Action required

Persons in control of a business or undertaking (PCBUs), electrical contractors, electricians and other electrical workers should note the following before commencing work:

  • PCBUs must develop and implement safe systems of electrical work and ensure that electrical workers are provided with such information, instruction, training and supervision as required to ensure, so far as is reasonably practicable, their health and safety.
  • A safe work method statement should be developed for the job.
  • The safe work method statement should consider the need for the use of a safety observer, insulated tools and/or suitable voltage rated insulating gloves.
  • The contents of a conductor enclosure should be identified and isolated prior to commencing any disassembly, penetration or installation of additional conductors by reviewing available drawings, visual inspection and verification.
  • The visual inspection should involve a thorough examination from the start and `end points of the conduit to work out what services run through it.
  • Conductors must be treated as energised and the procedures for working on energised electrical equipment followed until all conductors have been proven de-energised.
  • If practicable, find the main switch for the premises and turn off the power. Attach a danger tag or lock the switchboard to ensure the power remains off until the work is completed.
  • As a final check, use a voltage proximity tester to indicate the presence of an unidentified energised conductor within the enclosure.
  • Test Before You Touch safe work procedure should be followed in all steps of the job.

Further information

The Work Health and Safety Act 2011 (WHS Act) requires persons in control of a business or undertaking at a workplace to ensure, so far as is reasonably practicable, that workers and other persons at a workplace are not exposed to electrical risks arising from the business or undertaking.

Clause 147 of the Work Health and Safety Regulation 2017 (WHS Regulation) requires a person conducting a business or undertaking at a workplace to manage risks to health and safety associated with electrical risks at the workplace.

  • Australia Standard AS/NZS4836: 2011 Safe Working on or Near Low-voltage Electrical Installations and Equipment.
  • Visit www.safework.nsw.gov.au or phone 13 10 50.
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