More than fifty construction workers are killed each year electrocuted by contact with power lines found both overhead and underground on almost every construction site in the country.
The leading cause of contact involves heavy equipment like cranes, drilling rigs, concrete pumps, aerial buckets, dump trucks and backhoes. Of all heavy equipment contacts, cranes—either mobile or boom trucks--account for almost 60 percent of electrocutions.
But you can also be electrocuted when handling other construction materials and tools like long aluminum paint rollers, long-handled cement finishing floats, metal siding and roofing, metal ladders, and scaffolding.
Protect Yourself
Protect yourself from live power lines by looking around your work area and identifing the location of all power lines before you move or erect any equipment. Make certain that no part of any equipment comes any closer than at least 10 feet from the power line. And remember, this distance is greater for voltages above 50kV. Don't operate equipment around overhead lines unless you are authorized and trained to do so. Contrary to what many workers think, overhead power lines do carry enough voltage to kill and most are not insulated.
Maintain Safe Distances
Below are the minimum distances to maintain from power lines of different voltages. Remember, the higher the voltage running through the line, the farther away you need to be to be safe.
Also check your clearances from overhead lines feeding your jobsite through temporary service lines running from a power pole to the building before you set up ladders and scaffolding to make sure you maintain a safe distance during work at these heights. Changes in grading on construction sites can bring you closer to the lines, so make sure you check for any new grade work when you set up equipment from day to day. The following are general guidelines for 240-volt overhead line (temporary power) clearances.
Above a walkway 12 feet minimum
Above a driveway 15 feet minimum
Above a roadway 18 feet minimum
How Can You Avoid Power Line Hazards?
The following tips will help you and your crew avoid electrocution at your jobsite.
- Look for overhead power lines and buried power line indicators when working near or around them. Post warning signs to warn workers and other contractors
- Contact utilities for buried power line locations. Most states have a 48-hour DigAlert number to have underground utilities identified. Or call Dig Safe phone numbers to request power line locators.
- Always stay at least 10 feet away or more from overhead power lines.
- Unless you know otherwise, always assume that overhead and underground power lines are energized and functioning.
- De-energize and ground all electrical lines when working near them. Other protective measures include guarding or insulating the lines.
- Always use non-conductive wood or fiberglass ladders when working near power lines. This point is especially important when working from ladders or using concrete finishing poles in any construction site.
- Never allow a dump truck to advance or back up while under power lines. Almost all dump truck contact with power lines has been when the truck bed is raised.
Take Extra Care
Create awareness among your crews of unsafe electrical conditions on every jobsite, and monitor your crews practices during a project. They need to maintain their awarness, and will neede to inform other workers of hazards they know about—especially as the job progresses.
For example, metal scaffold is often used by different trades at different times during the construction. This means that everyone gaining access to the scaffold for their work must be made of any electrical hazards nearby.While the crew might take great care of erecting scaffolding near an overhead power line, another crew might not be so careful. Unfortunately, this has been the cause of death on more than one jobsite.
It might not be a bad idea to get some "High Voltage" warning signs and attached them to the scaffold to help raise awareness on your jobsite.
—Peter Kuchinsky owns CBA Construction Safety Check in Vista, CA., and is a contributor to El Nuevo Constructor. Contact him at question@cbaexpert.com.
Dig safe
Remember that what you don't see underground can hurt you too. Before you dig, you are required by law to call your state's DigAlert Service. This service will help you to locate gas, electric and telephone lines that are burried under the ground. Whether you are planting a tree, building a fence or laying foundation, getting in contact with a line with a shovel or pick can damage underground power lines—but most important, it can injure or kill workers. Safe digging is everyone's responsibility. In most states, you must call DigAlert a minimum of 2 days or 48 hours before you plan to dig.
 This powe line is dangerously close to the metal staging, and the people who will be working on it.
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 Even if you are not operating equipment that strikes a power line, you could be injured if you are stating near by.
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 Be very careful when setting up or moving ladders near overhead power lines, and get help if you need to control the ladder.
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 Locations of buried electrical lines should be marked by the power company before digging. Do not proceed with excavation until this is done.
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