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Arc Flash Information

An arc flash is a type of electrical hazard in which an electrical current short circuits through the air. This can happen when insulation becomes inefficient or fails and voltage (usually in excess of 120 volts) jumps to another exposed conductor or to the ground. Arc flashes are instantaneous, and can be very dangerous to electrical workers because they can create explosive blasts that cause burns and can throw shrapnel and debris.

  1. Causes

    • Electrical workers are more prone to arc flashes. An arc flash can occur when a worker brings a conductive material too close to an object with high amperage. Arc flashes can also occur when insulation is insufficient, meaning there are gaps, holes or breaks in the insulation. Improper installation, faulty equipment and degraded equipment are also causes. Impurities and corrosion at the surface level of the conductor cause arc flashes as well. In the area where an arc flash can occur, causing a spark with tools can ignite an arc flash.

    Injuries

    • In the past, the burns from arc flash and electrical hazards were thought to be just from the electrical shock. However, arc flashes are the culprit, able to produce heat as high as 35,000 degrees F, or four times the temperature of the surface of the sun. This can seriously burn individuals as far as 10 feet from the location of the arc flash. Because metal is melted in an arc flash, these droplets can ignite clothing. Burns can result from exposure to the arc flash, and the luminosity of the flash can damage the eyes.

    Arc Blast

    • Arc blasts are the result of high-energy arcs and can cause serious injury. According to Brady Arc Flash Solutions, a 10,000 A arc at 480 volts is equivalent to about 8 sticks of dynamite. Arc blasts can rupture ear drums, hitting victims with sound waves as loud as 160 decibels, and metal shards from explosive debris can be lodged into the body. Disorientation, concussions and falling injuries can also result.

    OSHA

    • OSHA, or the Occupation Safety and Hazard Administration, has helped create a six-point plan to prevent and reduce the risk of injury from arc flashes. These points include educating workers on the dangers of arc flashes, ensuring that workers have the right protective gear, and making sure they have the right tools when working. Facilities must also have safety programs that OSHA can evaluate, must be able to calculate the degree of an arc flash hazard, and must have warning labels on all equipment.

    Protection

    • Two types of suits used for burn prevention when working with electrical equipment are Category 2 PPE and Category 4 PPE suits. Category 2 PPE suits are designed to prevent second-degree burns. These suits have protection of up to 8 calories per cm squared, which is roughly equal to holding eight lit matches an inch away from your skin. Category 4 PPE can protect the body up to 40 calories per cm squared, but are large, expensive and hard to work with. These are usually required for higher voltage danger zones, but have many drawbacks due to their cumbersome nature, and can even create problems like heat stress while working.

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