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Electrical safety in mines

Information highlighting the importance of mine operators following precautions for all electrical work, while ensuring that all electrical hazards and risks are controlled.

Date: November 1, 2012
Keycode: On page content
Publication type: Alert
Industries: Electricity, Gas, Water And Waste Services. Mining And Quarries
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Description

This safety alert contains Information highlighting the importance of mine operators following precautions for all electrical work, while ensuring that all electrical hazards and risks are controlled.All electrical work includes electrical testing, fault finding and resetting tripped circuit breakers.

Electrical safety in mines

Guidance for mine operators that provides information about how to implement safety systems and install protective devices on electrical apparatus to prevent electric shock and electrocution.

Background

Since 1 January 2012, there have been 12 reported incidents of mine employees receiving electric shocks and flash burns from exposure to live electrical apparatus in Victoria.

For the majority of these incidents, mine operators reported that workers experienced ‘minor tingles’. However, the contributing factors identified indicate the incidents could have resulted in serious injuries and possible fatalities.

Common contributing factors across the reported incidents include:

  • working on live electrical equipment without standard operating procedures
  • the use of faulty electrical equipment, and
  • inadvertent contact with ’live’ electrical equipment near water or in damp situations.

The mine operators all had some safety systems in place, including electrical inspection and testing regimes. However, all reported incidents could have been prevented had appropriate control measures been in place.

Incident example

A licensed ‘A Class’ electrician was called to attend a fault on an underground fan. A 415 Volt, 3 phase, moulded case circuit breaker with a rated operating current of 250 amps had opened off under fault conditions due to a phase-to-phase short on the electrical circuit load side of the circuit breaker.

Without checking the condition of the electrical circuit, the electrician attempted to return electrical supply to the circuit by closing the circuit breaker. The huge inrush of electrical current drawn by the phase-to-phase short circuit far exceeded the working and fault handling capabilities of the circuit breaker. The resultant arc flash caused the circuit breaker to explode and the electrician received severe flash burns to his right hand and forearm.

An investigation into this incident revealed deficiencies in standard operating procedures, site authorisations and site-specific training.

Control measures

Mine operators must ensure that all electrical hazards are identified and risks controlled. Risk control measures include:

  • the installation and use of residual current devices (safety switches)
  • electrical inspection and testing regimes that are appropriate to the working environment and electrical equipment
  • use of appropriately rated Ingress Protection (IP) rated equipment
  • access restrictions to live electrical apparatus
  • use of qualified electrical personnel when performing electrical work
  • site-specific training including site authorisations and the use of permits and lock out/ tag out systems
  • implementation of standard operating procedures when fault finding, switching and isolating
  • use of appropriately rated personal protective equipment including gloves, face shield, full length clothing, footwear and rubber mats.

Advice

Observe the following basic precautions for all electrical work, including electrical testing, fault finding and resetting tripped circuit breakers:

  • ensure a test is carried out to confirm the condition of the installation and positive confirmation of isolations (ie test before you touch)
  • ensure appropriate protective equipment including protective clothing is utilised
  • ensure that the testing equipment is appropriate for the voltage that is to be tested.

Further information

  • Energy Safe Victoria (ESV) – esv.vic.gov.au
  • Code of Practice for Safe Electrical Work Low Voltage Electrical Installations (ESV)
  • Code of Practice on Electrical Safety for Work on or Near High Voltage Electrical Apparatus (“Blue Book”) (ESV)
  • AS/NZS 4836:2011– Safe working on or near low-voltage electrical installations and equipment


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