A key focus of the company is electrical safety, with arc flash hazard risk management central to this focus. Specialist skills include: qualitative and quantitative risk assessment; protection scheme and settings optimisation; arc fault containment assessment; and arc flash risk mitigation development and implementation planning. Some guidance:
Understand Your Arc Flash Risks
Understanding your site specific arc flash risks is essential to determine whether they are acceptable or require mitigation. Some things to consider:
- Community and regulatory obligations for the provision of a safe working environment and specific requirements for the mitigation of arc flash hazards.
- Condition of switchboard equipment and maintenance practices.
- Likely electrical energy that could be delivered by your power system to each switchboard during an arc fault.
- Open door arc flash energy boundaries around each switchboard for each level of Personal Protective Equipment (PPE) used in switchrooms.
- Closed door switchboard Arc Fault Containment (AFC) capabilities. Assessments required.
- Activities and man-hours spent in switchrooms: working in the vicinity of switchboards; working inside switchboards; switching; and racking.
- Qualitative risk assessment of injury to personnel resulting from an arc flash incident for each switchboard type. Risk matrix required.
- Quantitative risk assessment of fatalities/serious injury resulting from arc flash incidences sitewide. Risk acceptability limits required.
- Your risk acceptability status and targets. Are your risks As Low As Reasonably Practicable (ALARP)?
Evaluate Your Risk Mitigation Options
There are many arc flash risk mitigation options. Determining which are optimal in terms of costs and timing, for achieving the risk targets for your site, usually requires careful evaluation. Some things to do:
- Determine the mitigation options required to address risks associated with the various work activities and switchboard types. Options may include:
- De-energise before commencing work.
- Restrict access to switchboards.
- AFC via replacement or modification.
- Arc fault energy reduction via faster clearing.
- Arc fault energy reduction via reduced fault level.
- Arc fault energy diversion.
- Remote operation of switchgear.
- Arc flash prevention by design or maintenance.
- Arc energy boundary labelling.
- Adequate PPE for arc energy boundaries.
- Use qualitative risk assessment techniques to develop a basic risk mitigation plan to achieve ALARP risk targets.
- Use quantitative risk assessment techniques to evaluate the effectiveness of the mitigation options on individual and group risks. Prioritise mitigation options accordingly and finalise risk mitigation plan.
- Cost risk mitigation plan and prepare budget funding requests.
Implement Your Risk Mitigation Plan
For sites less than 15 years old, the implementation of a risk mitigation plan should be relatively simple and swift. For older sites, the opposite is likely and may take several years to implement. Some things to do:
- A first step is to turn the risk management plan into a workable implementation plan. Considerations may include:
- Management timing commitments for achieving risk mitigation targets.
- Resource approvals: funds and site personnel.
- Operations disruption constraints.
- Maintaining grading coordination whilst implementing protection changes.
- Equipment delivery timing.
- Engineering design & construction timing.
- Execute implementation plan using typical project management procedures. Activities may include:
- Development of detailed task lists for project control and assessment of safety and production loss risks.
- Coordination with Operations and Maintenance schedules.
- Ensure personnel affected by the risk mitigation work receive adequate training on the changes. This should include instruction on arc flash causes, consequences and the equipment and systems in place to mitigate the risks.
Mitigation Tips
- One of the cheapest and most effective arc flash risk mitigation practices is better control of access to switchboards to reduce the time personnel spend in the vicinity of switchboards.
- Chain off the rear of switchboards that have vents.
- Discourage thoroughfares, meetings and non-essential personnel in substations.
- Encourage job planning to minimise time spent inside or near switchboards.
- Ensure that no more than one person is in the line of fire when switching or racking.
- Another relatively cheap and frequently very effective arc flash mitigation practice, is to reduce arc fault energies by tightening up existing protection settings.
- Installing labels on switchboards to advise personnel on the correct PPE requirements, when working in the vicinity of the switchboards, provides a constant visual reminder of arc flash hazard risks and encourages PPE compliance.
- Before purchasing new switchboards, obtain correct copies of the arc fault containment rating certificates and that your power system fault levels and clearing times will be within the limits specified on the certificates.
- Personnel that don’t understand arc flash risks are likely to be the biggest risk. Explain the risks and get them involved in the risk assessments.