Common causes of arc flash incidents

One of the primary reasons for electrical injuries is electric arcing, commonly referred to as arc flash. Arc flash incidents are often related to human error when work is being performed on or around energized electrical equipment. Even when the work involves control equipment and the handling of small, low-voltage electrical components, the risk of arc flash still exists. 

An arc flash may cause severe burns, hearing loss, eye injuries, lung damage, and blast injuries. Arc flashes are rare but when they do happen, the impact on personnel and the business can be significant. Maintaining a heightened sense of awareness can help to protect equipment and save lives. Don’t get caught off guard.

Accidental contact

Working around exposed, live parts presents a hazard and, the fact is, accidents do happen. When it comes to accidents around electrical equipment a mere drop of a tool or physical contact with the live part can set off an arc flash and instantly generate an energy explosion releasing temperatures in excess of 35,000˚F.

Testing and troubleshooting live equipment

The importance of uptime for critical processes often results in the need to perform troubleshooting on live equipment. If a test probe accidentally establishes a phase-to-phase or phase-to-ground connection during a routine check, it could result in personal injury and downtime. Ensuring the right tools are used for the job will help to reduce the risk and probability of an arc flash occurring.

Installing and operating live equipment

Adding or removing circuit breakers, contactors or components in energized control circuits or motor control center (MCC) buckets, or installing or removing MCC buckets from a live bus, can incite an arc flash. Routine operation of breakers and disconnect switches, especially racking breakers in or out of both low- and medium-voltage switchgear, all present a risk of arc flash in equipment that has not been properly installed, tested and maintained.

Poor condition of equipment

Damaged insulation, or loose or incorrectly wired control connections can all lead to failures and ultimately arc flash incidents. Insulation breakdown can cause arcing or heat, potentially triggering an arc flash event. It’s important to verify the integrity of cable installation prior to working on any electrical equipment. Missing or damaged insulation, barriers and guards may increase worker exposure to hazardous locations and components. Damaged equipment enclosures, operating mechanisms, cable/bus supports are important factors in assessing the likelihood of exposure to hazards and probability of an accident occurring.

Improperly maintained equipment and tools

The primary purpose of a circuit protective device is to interrupt current flow after a downstream short circuit or fault is detected. If the protective device has not been properly maintained and it fails to interrupt the fault, the result could be an explosive arc flash resulting in damage to equipment and personnel. Regular testing and preventative maintenance can to help ensure the equipment will operate within manufacturers tolerances. Poor environmental conditions such as moisture or a build-up of conductive dust or contaminants can result in corrosion or compromised insulation systems. Damaged or improperly rated tools and test equipment, including worn insulating material for screwdrivers and wrenches, can lead to accidental arcing from conductors to ground.