With Electrical Safety Fortnight coming up we thought it timely to explore an emerging issue that has the potential for significant consequences: Arc Flash.
An arc flash is a sudden release of electrical energy through the air when a high-voltage gap exists and there’s a path to ground or lower voltage. It’s like lightning — but it can happen inside electrical panels, switchboards, or other electrical equipment we come across every day.
An arc-flash injury can occur when a person or metallic object come within the arcing distance. These incidents have been found to be caused by dust, corrosion, accidental contact, or even a dropped tool.
During an arc-flash, a significant amount of radiant energy is released, which can result in hazardous flames and arc blast. An arc-flash has been known to result in severe burns, damage to eyesight and hearing. In addition, the pressure waves can cause debris (such as steel fragments and molten copper) to exit the equipment at a high velocity, creating a serious shrapnel hazard to personnel. In just a fraction of a second, temperatures can reach 20,000°C, melting metal and causing serious burns, injury, or worse. Arc flash incidents can and have been deadly.
The severity of the arc-flash energy is determined by the level of fault current and the speed of the upstream protection device operating time, and in recent decades this equation has become a more prevalent risk.
The reason is that, as the demand for electricity has grown, electric utility transmission and distribution systems have been upgraded. This has resulted in lower effective impedances and higher system fault levels. In addition, the increase in power demand, particularly at industrial and commercial sites, has resulted in higher transformer ratings. This means the fault energy available during an arc flash is much higher, and overall, modern power systems can be far more hazardous than those of the past. This is not just an issue for supply networks but is relevant to any site operating with substantial electrical infrastructure, including shopping centres, industrial sites, theme parks, data centres and solar facilities.
However, most arc flash incidents are preventable.
Understanding the risks is the first step in protecting yourself and your coworkers. It’s not just about electricians — anyone working near electrical equipment should be aware.
So, what should be done about it? There are several areas to consider in managing arc flash risk.
- Training and awareness: Make sure everyone who works with or around electrical systems understands what arc flash is and how to stay safe.
- Reinforce that there is to be no live work: Safe systems of work call for de-energisation before any work commences on electrical equipment, and it’s critical that this protocol is observed.
- Look for early warning signs with regular inspections: Old or degrading electrical panels and switchboards present an increased risk. Often these may have no escutcheon inside the panel door, exposed live parts or cracked insulation.
- Quantify the level of risk: Engage an appropriately qualified electrical engineer to conduct an arc flash study to assess and quantify the risk. This should also result in recommendations to reduce the risk where necessary, using the hierarchy of controls.
- Where there is a risk, use proper equipment: Use protective gear (like arc-rated clothing, gloves, and face shields – as determined by the arc flash study) when working on or near live equipment.
- Labelling and signage: Electrical panels should have clear warning labels showing arc flash hazards and necessary protection levels.
- Preventive maintenance: Keep electrical equipment and panels clean and properly maintained to reduce the risk of faults that can cause arc flash. This should include a regular inspection and test program.
- Engineering controls: Use designs and tools that limit the need to work on energised equipment whenever possible.
With electrical safety specialists who have expertise in this field, QRMC can assist to identify and manage arc flash risk.
