Employee fatally injured while reinstating 6600V circuit breaker

Incident background

An employee has died while racking in a 6600V (6.6KV) circuit breaker at a power station. The causes of the incident are still being established but it appears to have occurred when the 6.6KV circuit breaker was being placed back into service. The employee was exposed to an arc flash, electrical explosion, molten debris and super-heated gasses.

WorkSafe is currently investigating the incident.

Hazards and effects associated with HV electrical energy

An incident involving an arc flash and/or electrical explosion can expose people to levels of energy that could lead to severe burns or death.

An arc flash may produce hazards including:

• a pressure wave where the arc is generated
• plasma/super-heated ionized gas (over 19,000°C)
• molten debris/molten sprays (copper, aluminium)
• harmful light and noise (approx. 160dB)
• toxic gases and fumes

Employees exposed to these hazards may sustain one or more of the following injuries:

• Burns
• Injuries from the release of molten materials
• Damage to hearing and eyesight
• Inhalation of super-heated toxic gases causing damage to lungs

Actions following an incident

Duty holders with management or control of workplaces where HV electrical apparatus is installed must eliminate risks associated with using the apparatus, where it is reasonable and possible to do so. If the risks cannot be eliminated, they must be reduced as much as possible.

Following any HV electrical arc flash or explosion, employers should ensure that:

• employee activities in the vicinity of live HV apparatus stop until causes of the incident are determined
• the incident is thoroughly investigated by suitably qualified and competent personnel

If there is a requirement for tasks to continue, including racking in/out 6.6 KV circuit breakers, all HV electrical energy should be isolated/de-energised before starting the task, or other controls should be implemented to prevent employees being exposed to electrical risks, including those referred to above.

Recommendations

WorkSafe recommends employers with management or control of workplaces where HV electrical apparatus is installed conduct a thorough review of:

• the electrical safety management system
• procedures for operation of switching and racking HV metal clad switchgear
• risk assessment for potential arc flash hazard
• risk assessments and risk controls
• maintenance of HV electrical apparatus
• employee training and authorisations
• procedures such as access to HV electrical apparatus
• training in the selection and use of personal protective equipment

Support for people affected by a serious workplace incident

Have you been affected by a workplace fatality, illness or serious injury?

For advice and support, call:

• Beyondblue: phone 1300 224 636
• Lifeline: phone 13 11 14.