Everyone knows that electricity, although all around us and absolutely essential, can also be dangerous. We are all aware that we need to take great care, for example, with electrical appliances near water, and that loose wires and damage can be dangerous. When in the industrial and commercial sphere – where greater voltages and amperages may be present – things become even more dangerous.
For example, there’s the danger of arc flash, or an electrical arc. You may not be familiar with arc flash, but it is in fact a very dangerous phenomenon, and one that needs careful attention where people are working with electrical circuits. A simple explanation: any electrical circuit needs to be complete to operate, so there has to be a physical connection for the current to flow around it. However, electric current is capable of jumping gaps in some cases. Where this happens – when an electrical circuit is effectively completed in the air, you have arc flash.
Now, with small currents – batteries and so forth – there is little danger. But for high-voltage circuits, and especially those beyond 220volts, an arc flash can be very, very dangerous indeed. Let’s have a look in more detail at why this is, before we go on to talk about how to protect against arc flash.
Why Arc Flash is Dangerous
Imaging a very powerful electric circuit, perhaps used to power a large piece of equipment. In normal circumstances, the current is contained. If, however, a fault occurs and the current is allowed to form a connection in the air, the result could be catastrophic.
Arc flash usually occurs very, very quickly – perhaps faster than the blink of an eye – yet in that minute fraction of time, a release of energy so rapid and powerful occurs. This energy takes the form of heat and light. Indeed, a powerful arc flash can cause heat so intense it can melt many materials in an instant, even some metals.
The potential danger for those around is clear; anyone working at the point of the flash will undoubtedly be susceptible to burns, usually severe and often irreversible, while arc flash can cause other permanent damage to the eyes, the ears and internal organs, the latter thanks to the involuntary inhalation of hot gases.
Minimising the risk of arc flash is therefore clearly essential, and protection against it equally so.
Prevent and Protect
How do you prevent arc flash? Accidents will happen, but to minimise the risk of arc flash it is important to understand where and when it may occur. First, it is most likely to occur at the point a high-voltage circuit is switched on. The surge of power causes this. Therefore, any required start-up procedures and precautions must be followed Then, it may occur where faults are present. These may be able to be uncovered by using accurate metering systems, that can detect if voltage is actually present in a seemingly dead system, or indeed if residual energy needs to be got rid of before the equipment is safe.
However, there remain some occasions when all is done to prevent arc flash, yet it still happens. This is why anyone working in an area of risk should be equipped with the relevant protective clothing. This should include covering for the hands and arms, plus a face protection that also shields the eyes from intense light. Also, breathing apparatus in case of gases, and also ear protection for the loud explosion.
All of this equipment is available from respected suppliers – such as Arc Flash, so make sure your workforce has the right gear, and is fully up to speed with the dangers of arc flash.
