What is an Arc Flash?

An arc flash, also known as an electric arc, is the rapid release of energy that occurs as the result of an electrical arcing fault. Arc flashes can be very dangerous to people who are exposed to it. The term “flash” refers to the actual flash of light that is emitted during the process and also, to the speed at which it occurs. Generally, an arc flash is over and done within a second or so.

A very common example of an arc flash is what happens when an incandescent bulb burns out. An arc is created across the filament after it breaks. This arc covers the filament in plasma, which we see as a blue flash. To protect circuits from these arc flashes, most bulbs come with a built-in fuse.

A majority of 480 V electrical systems can cause an arc flash hazard. The potential increases with voltage. A 600 V electrical unit, for instance, is at higher risk of causing an arc flash. Higher voltages often lead to spark jumps, which can induce an arc flash even without actual physical contact. These arc flashes can also sustain across greater gaps.

Power lines that exceed 1000 volts can create arc flash hazards that affect vehicles, birds, and even people.

The types of arc flashes

There are generally two kinds of arc flashes. Firstly, we have a confined arc flash. This occurs within a motor control center or a distribution box. As the name indicates, such an arc flash is contained on three sides. However, there is no containment where the box is left open. So, the concentrated energy escapes through this opening. If a person happens to be near the box at the time, it can lead to grievous injuries.

The next type is the open arc flash. This is the kind of arc flash that occurs in an open area. The energy travels to all sides, igniting anything that is close enough.

Protection

There are several ways to protect people from arc flashes. One way is to provide them with PPE or Personal Protective Equipment. Other than that, it is always a wise idea to de-energize electrical equipment before working on it. But, sometimes de-energization itself can lead to an arc flash. In this case, it is best to operate by remote.

Another option is to design electrical systems in a way that they regulate the factors that lead to an arc flash and determine its intensity. In other words, configurations must be implemented with safety in mind.

Circuit breakers also aid in reducing the possibility of an arc flash. However, it is best to operate them from a distance as they too can fail in preventing an arc flash.