Canadian Occupational Safety

20 Canadian Occupational Safety www.cos-mag.com I n July 1999, Curtis Weber was 17 and working on a construc- tion site in Saskatchewan. He and two co-workers were put- ting a steel grain bin on top of a hopper bottom. They had identifi ed an overhead power line, and as they approached the overhead line, it was Weber's job to steady the bin against high winds. But the crane operator failed to lower the boom far enough and backed into the power line. Weber was hit by 14,400 volts of electricity, which went through his body three times. He suffered third- and fourth-degree burns to more than 60 per cent of his body, including his face. His right arm and left leg were amputated. Power lines are often present on construction sites and pose a serious hazard to workers. Because electricity naturally seeks the ground, a piece of equipment or machinery that touches or goes near a line can send high-volt- age electricity (more than 750 volts) travelling downwards through the equipment. Within seconds, the sur- rounding ground and other equipment may also become energized. The main danger of power lines is, of course, electrocution, which may cause severe internal and external burns and often death. Sometimes, a foot or hand has to be amputated. The electric current can also stop the heart. "They may look pretty safe: a line up above, nothing sparking. But touch it or come close to it and the energy that's travelling in that line will want to jump over and come to ground. It will travel down the easiest path it has," says Scott Saint, chief public safety offi cer at the Electrical Safety Authority in Mississauga, Ont. "Power lines are very lethal. They can kill in an instant, before you even recognize there's a danger." In Ontario, overhead power-line contact has killed 24 people in the past 10 years. Moreover, construction workers are at an especially high risk: 70 per cent of power-line contacts in the past 10 years have occurred on con- struction sites. Power-line contacts most com- monly affect construction workers operating excavating equipment, for example, backhoes and larger excava- tors, says John Curran, manager of safety and environment at Newfound- land Power in St. John's, N.L. Other examples of heavy equipment that can contact power lines are cranes, boom trucks and garbage dumpster trucks. An increasing number of incidents also involve dump trucks, Saint says. "We're seeing a much higher inci- dent level of contact by dump trucks on power lines. That's a danger to the dump truck operator and it's a danger to the people around there because, in an extreme case, the truck can pull the line right down," he says. Many construction companies are recognizing the need to get the mes- sage out that dump truck drivers need to be more aware of their boxes and remember to lower them, Saint says. More companies are also requiring that trucks have buzzers built into the truck cab. As the box starts to rise, it triggers a buzzer to sound, and the noise stays on until the dump box is lowered. "It's a simple measure, but it can be very effective because it's a reminder: you have the buzzing going on, you know you have to lower the box," he says. "It's a busy construction site. People are moving quickly and, sometimes, people forget that their box is raised and they have contact with the power line." Construction workers working with tools or materials capable of making contact with electrical equipment are also at risk, he says. Tools such as lad- ders and scaffolds are good conductors of electricity. "If contact is made in these instances, the path to ground will undoubtedly be through the worker and severe injury is imminent. These types of contacts with energized power lines are more likely to result in death," says Curran. Power lines can be just as dangerous even when there is no direct contact. Workers themselves and the metal equipment they work around can attract electricity, causing the electric- ity to jump, or "arc," from the lines to a conducting object, such as a metal ladder, truck or person. The chances of arcing increase with the voltage. Moreover, while most concern is around high-voltage lines, it's impor- tant to remember that power lines carrying fewer than 750 volts can kill. While going through the vehicle to get to the ground, electricity will often go around the operator in the cab, says Curran. "Of course, this is not always the case, and workers must remain vigi- lant at all times when working around electrical equipment," he says. "Any worker standing near a piece of equip- ment when contact is made is also at Source: Electrical Safety Authority Source: Electrical Safety Authority Source: Electrical Safety Authority Source: Electrical Safety Authority Source: Electrical Safety Authority Source: Electrical Safety Authority things construction workers need to know about power lines around safe Play it 70 per cent of power-line contacts occur on construction sites By Linda Johnson safety and environment at Newfound- land Power in St. John's, N.L. Other Construction workers working with tools or materials capable of making contact with electrical equipment are also at risk, he says. Tools such as lad- around power lines THIS IS SHOCKING: In addition to the truck, the ground around it is also energized. It's called ground gradient, which can cause a severe or even fatal shock. KEEP CALM: If the driver stays inside the cab and doesn't step out of the vehicle, he can avoid being electrocuted. Also, fi rst responders should not rush the scene until the power has been disconnected by the utility and the area has been deemed safe.

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