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94Electric Shock From Mobile Lighting Plant #2

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Brief Description of Incident/Accident & Description of Consequences/Outcomes:


A mine technician received an electric shock from a mobile lighting tower in an open cut mine. The technician was adjusting wiring in an electrical enclosure when he contacted a 240 V conductor.


Mobile lighting towers are used extensively in open cut operations to provide area lighting for night time operation. These may be wheel or skid mounted, and are powered by a diesel engine driving a 415 V three phase alternator. Two electrical enclosures, similar in appearance, contained the electrical control equipment. One was for 415 / 240 V circuits, the other was for 12 V DC (extra low voltage[ELV]) circuits. The 12 V DC circuits were for engine management and monitoring, and included a 12 V powered programmable logic controller (PLC). The mine technician was a mechanical tradesperson with auto-electrical skills, and authorised to work on ELV circuits only. He was trying to diagnose a fuel level monitoring fault, and attempted to re-seat the input plug to the PLC.

Unknown to him, a 240 V conductor had been wired to the PLC to notify the PLC that the alternator had built up voltage. This conductor was exposed for a short length at the back of the plug, allowing the technician to make inadvertent direct contact with his thumb. His other hand was on the door of the enclosure, completing a circuit across his chest.

Identified Root Causes:


The 12 V DC enclosure was not lockable, did not require special tools for access, and was not fitted with signage warning of electricity. The 12 V DC enclosure is regarded as an operating area as defined in AS 3007, and as such it is not permissible to have exposed conductors at a voltage above ELV inside the enclosure.

Energy Type(s) Involved:

Direct contact with live electrical conductors

Equipment Type(s):

Lighting Plant

Root & Contributing Cause(s):

LTA design

LTA equipment modification

Stated or Potential Consequence(s):

Potential Fatality

Preventative/Recommended/Accepted Steps of Risk Mitigation, Points of Interest:

· Owners of the same or similar apparatus should immediately determine whether exposed or unprotected conductors above ELV are present in enclosures that are regarded as “operating areas”.

· Mines should check that electrical apparatus complies with AS 3007 where appropriate. Regard must be had for the classification of operating areas, including enclosures of electrical equipment.

· Where complete protection by insulation or barriers cannot be achieved, enclosures must be secured by a key or special tool, and accessed only by skilled persons. Signs warning of the danger of electricity must be fitted to such enclosures.


New South Wales Department of Primary Industries, Minerals and Petroleum


Here are the results.


Reference Type:

Mine Safety Report #SA00-07

Mine Type:

Surface Mine







Australia, New South Wales

ICAM Categories

Organisational Factors

• LTA adherence to safe system of work

• LTA commissioning procedures

• LTA compliance with electrical standards

• LTA equipment

• LTA equipment integrity

• LTA maintenance

Task or Environmental Conditions


Individual or Team Actions


Failed or Absent Defences


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