07 Mar Power Lines and Mobile Cranes

Power Lines and Mobile Cranes

Mobile cranes, dump trucks, aerial lifts, concrete pump trucks, and other equipment operating near overhead power lines can expose workers to electrocution, electrical arcing, fire, and serious or fatal injuries. Electrical contact does not have to occur for an injury to happen—electricity can arc across an air gap when equipment gets too close to an energized line.

Treat all overhead power lines as energized unless the utility owner/operator has confirmed that they are de-energized and visibly grounded at the worksite.

Before Work Begins

Before operating a crane or other equipment capable of reaching an overhead power line:

• Survey the work area and identify all overhead electrical lines and equipment.
• Determine whether any part of the equipment, load, load line, rigging, or attachments could come within the required minimum clearance distance.
• Contact the utility owner/operator when necessary to determine the line voltage.
• Establish the required clearance before operations begin.
• Whenever feasible, have the utility owner/operator de-energize and visibly ground the lines or provide other appropriate protection.
• Clearly identify the power-line hazard and communicate it to everyone involved in the operation.
• Establish boundaries, warning lines, barricades, or other means necessary to prevent equipment from entering the prohibited area.

Never rely solely on visual estimates of the distance between equipment and a power line.

Minimum Clearance Distances

For crane operations covered by OSHA construction requirements, when the line voltage is known, maintain at least the following minimum clearance from energized power lines unless another permitted protective option is implemented:

When the voltage is unknown, do not assume the line is low voltage. Obtain the voltage from the utility owner/operator or use the clearance required by the applicable OSHA standard until the voltage has been established.

The clearance applies to every part of the equipment and load—including the boom, load line, rigging, taglines, and material being handled.

Safe Operating Practices

When equipment operates where encroachment on the required clearance is possible:

• Use a dedicated spotter when required to monitor clearance.
• Ensure the spotter is positioned where the distance between the equipment and power line can be accurately assessed.
• Maintain reliable communication between the operator and spotter.
• Operators must immediately obey a stop signal, regardless of who gives it.
• Use nonconductive taglines when taglines are necessary near electrical hazards.
• Do not allow employees to touch the crane, load, rigging, or equipment while electrical contact is possible.
• Consider boom movement, load swing, wind, equipment movement, and changing ground conditions.
• Maintain required clearance while traveling under or near power lines.
• Use warning lines, barricades, signs, or other controls necessary to identify the electrical hazard area.

A spotter does not eliminate the minimum clearance requirement.

If Equipment Contacts a Power Line

If a crane or other equipment contacts an energized power line:

• The operator should remain inside the cab whenever possible.
• Warn everyone nearby to stay away from the equipment and load.
• Do not allow anyone on the ground to touch the equipment, load, rigging, or attached materials.
• Contact the utility company and emergency services.
• Assume the equipment and surrounding ground remain energized until the utility confirms the line has been de-energized.
• If possible and safe, the operator may attempt to move the equipment away from the line without leaving the cab.

If fire or another immediate danger makes it necessary to leave the equipment, the operator should jump clear without simultaneously touching the equipment and ground, land with both feet together, and move away without taking normal steps to reduce exposure to hazardous ground-potential differences.

Never approach equipment that has contacted a power line to rescue the operator until the electrical hazard has been controlled.

Remember

Power lines do not have to be touched to kill. Electricity can arc to equipment that enters the danger zone. Identify overhead lines before work begins, determine the voltage, establish the required clearance, use a dedicated spotter when required, and have lines de-energized and visibly grounded whenever feasible.

When working around overhead power lines, distance is one of your most important protections.