Workplace Safety: Protecting Workers from Power Lines

Dr. Purushothaman
December 6, 2013

Workplace Safety: What You Need to Know about Arcs

Today there is more electricity than ever flowing through neighborhoods and more opportunity for large energy discharges. An arc flash is a voltage breakdown of the resistance of air, resulting in an arc that can occur where there is sufficient voltage in an electrical system and a path to ground or lower voltage.

In other words, energy wants to follow the path of least resistance and will jump from one conductor to another. The energy given off during this arcing is called arc flash. The massive energy released in the fault instantly vaporizes the metal conductors involved, blasting molten metal and expanding plasma outward with extreme force. A typical arc flash incident can be inconsequential, but could easily produce a more severe explosion. The result of the violent event can cause destruction of equipment, fire, and injury—not only to the worker but also to any people nearby.

About 10 arc flashes occur every day in the United States—and they cause disastrous consequences. While contact burns occur internally, arc flash burns and explosions are the result of a powerful electrical current outside of the worker's body and they are hideous.

To get a good idea of the heat arcs produce, arc flashes can reach 18,000°F—or about half the heat energy of a bolt of lightning. When placing a drill rig in an upright position near or around electrical wires, workers need to know how much voltage is in those lines. That way, they'll know how many feet are required to create a safe distance and prevent arcing between the wire and the rig. Before working under or near overhead power lines, make sure you maintain a safe distance. For very high voltage lines, ground any cranes or rigs that can become energized. If working on power lines, make certain the lines have been de-energized and grounded by the lines' owner or operator. Other protective measures like guarding or insulating the lines help prevent accidental contact.

Employees not qualified to work with electricity and all mechanical equipment should remain at least 10 feet away from overhead power lines. If the voltage is more than 50,000 volts, the clearance increases by 4 inches for each additional 10,000 volts.

Workplace Safety: What Protection Does PPE Offer?

Employees who work directly with electricity should use the personal protective equipment required for the jobs they perform. This equipment may include rubber insulating gloves, hoods, sleeves, matting, blankets, line hose, and industrial protective helmets designed to reduce electric shock hazard. All of these help reduce the risk of electrical accidents. Insulated gloves should be rated to at least the maximum current on the line. If working in wet conditions, workers should have non-conductive soles on their shoes.

Workplace Safety: Tools and Electrical Safety

Appropriate and properly maintained tools help protect workers against electric hazards. It's important to maintain tools regularly because it prevents them from deteriorating and becoming dangerous. Check each tool before using it. If you find a defect, immediately remove it from service and tag it so no one will use it until it has been repaired or replaced. Specifically, workers should see to it tools are maintained in good condition. And remember, plastic or rubber handles are not for comfort but for insulation against electrical accidents. If this cover becomes cracked, torn, or loose, it should be replaced immediately. When using a tool to handle energized conductors, check to make sure it is designed and constructed to withstand the voltages and stresses to which it has been exposed.

Workplace Safety: The Role of the Health and Safety Program

Every good safety and health program provides measures to control electrical hazards. The responsibility for this program should be delegated to someone with a complete knowledge of electricity, electrical work practices, and the appropriate OSHA standards for installation and performance.

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