Electrical arcing happens when an electric current flows through the air between two conductors, as a result of the electrical breakdown of gas that produces an ongoing electrical discharge. This may be the result of gaps or breaks in the insulation, equipment failure, impurities such as dust, corrosion and normal wear and tear on the surface of the conductor, overloaded plug outlets, or frayed and exposed wires.
When this happens, an electric current ceases to travel along its intended path and instead travels through damaged insulation from one conductor to another, or it jumps in an arc to a nearby grounded object. The uncontrolled conduction of electrical current and the ionization of the surrounding air is what causes electrical arcing. The intense heat and light energy at the point of the arc is called the arc flash.
Arc faults are caused by a variety of factors, including insulation failure, accidental contact with energized equipment, or poorly maintained electrical systems and equipment. Preventing an arc flash from happening in the first place, or at least the possibility of it is minimized, by taking precautionary and preventive measures such as baseline testing. and making sure your electrical equipment is maintained. Consulting with an arc flash expert is recommended, and this expert will be able to provide you with a risk assessment and mitigation recommendations for compliance with arc flash hazard requirements. Part of compliance will necessarily include the installation of safety devices, but you need an expert’s assessment to identify the riskier areas and where it is most feasible to install the said safety devices.
Electrical arcing, arc faults and arc flashes are extremely dangerous because it is a concentration of the arc fault current and voltage in one place, resulting in the release of enormous energy that could potentially cause injury through severe burns and fire. As explained on the Vehicle Lab a MIG welder is a essentially a controlled arc; In the cases of the electrical failure outlined above, the arc isn’t controlled and can jump to another grounded object. Similar to these welders though, they can also cause damage to eyesight which is why TIG and MIG welders wear a protective helmet. And because arc flashes travel through the air, they can cause injury to you and the people around you. Statistically, the risks of an injury form an arc fault is higher than injury from an electric shock.
Also, the heat generated from an electric arc can break down the insulation of a wire and can trigger electrical fires. Or the extreme temperature of an arc can vaporize the conductors so that a considerable pressure of wave and sound blast can form. An arc blast then becomes like an explosion, and the blast and shockwave can cause considerable property damage, serious physical, even auditory injury. Arc flashes may also release poisonous gases that can be dangerous to a person’s health, potentially causing lung damage. And of course, arc flashes can cause great damage to electrical equipment and other nearby property. Professionals have described temperatures of the arc as sometimes reaching four times the temperature of the Sun’s surface.
Electrical Arcing is prevented by the proper installation of over-current protection devices that work by opening the circuit. Since 2002, the NEC has begun to require all new construction to include arc fault circuit interrupters or AFCIs in branch circuits inside electrical panels. AFCIs are similar to GFCIs that work as protective devices by shutting down the circuit once a stray current is detected.
Another preventive measure that electricians and other individuals can take to prevent injuries or accidents resulting from electric arcs and arc flashes is to de-energize. Deenergizing equipment before working on them means that you eliminate or at least minimize the chances of stray electric currents jumping through the air between conductors, or jumping to you. In fact, the NEC requires that an Electrical Hazard Analysis be conducted before working on or near electrical conductors that could be energized. This Electrical Hazard Analysis will help determine what protective measures should be taken while work is being done, and what other additional measures should be taken to protect both the electrician and other individuals regularly in contact with potential energized conductors. Most injuries resulting from an arc flash happen when equipment is being used. Hence the prudence of de-energizing before any kind of electrical work is done.