Last Modified on 06/17/2002 15:40:02Your Safety: Working Near Power Lines
Trees and electricity are both beneficial, but when the two come together, problems arise. Add a third element, a human, and a life may be in jeopardy.It's a harsh reality that workers pruning trees near energized power lines face serious hazards from contact with those lines or related equipment. A worker's body may come into direct contact with an energized line. Tools or other conductive material, such as severed tree limbs, may touch the lines, resulting in an indirect, but equally dangerous, contact. Either way, you are exposed to electrical shock by becoming a path to the ground - between an energized conductor and grounded equipment, tools or trees - or by becoming a path between two conductors.
The electrical current passing through the body can cause third degree burns, irregular heart action or stoppage, or the stoppage of breathing. In addition, you may be exposed to thermal burns or flash burns from arcing.
If you're a tree worker, your first concern should be to protect yourself from such hazards.
Plan Ahead
Safe Work Practices
Underground Electrical Equipment
Tree Spraying
Electrical Emergencies
Plan Ahead
Before any work begins, the job site should be inspected to locate overhead power lines and electrical equipment. If there appears to be any conflict, contact the electric utility company so measures can be taken to ensure a safe work environment.Remember, the distance the tree is away from the energized lines can be deceiving. In some cases, it may be just as dangerous to trim a tree 10 to 20 feet from energized lines, as it is to trim one much closer, because a long, large branch can fall into the lines and conduct electricity back to the trimmer who believes he has maintained more than adequate clearance.
Unqualified individuals should never trim trees around energized lines. Where electrical hazards exist, only qualified line clearance tree trimmers should do the work. Climb the side of the tree away from any powerlines: the crotch of the tree selected for tying in should be over the work area, but located in such a way that a slip or fall would swing away from energized lines.
Ladders and aerial equipment, including insulated aerial equipment, should not be placed in contact with electrical conductors. If an aerial device does contact an electrical line or conductor, the truck supporting the device and any other attached equipment should be considered energized. Anyone touching the equipment could be injured or even killed.
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Safe Work Practices
Determine whether you and your crews can maintain the 10 foot clearance from power lines required both by state and federal regulations. Arizona statute working clearance requires that a person may not get any portion of his body, hand tools or material he's handling within the radius of six feet of a powerline rated at 50,000 volts or less. If the line exceeds 50,000 volts, clearance requirements increase.Mechanized equipment must maintain a minimum 10 foot distance from powerlines and conductors rated at 50,000 volts or less. The equipment includes load, cables, tag lines and any other attachments. If the powerline is rated more than 50,000 volts, the clearance requirement exceeds 10 feet.
Consider these clearance requirements for work near overhead powerlines as your "circle of safety." These working clearances are minimum safety clearances. Whenever possible, even greater clearances should be maintained.
If your work is going to bring you closer than the above clearances allow, notify the electric utility company promptly. No work should be performed near energized conductors until danger of contact with those conductors has been effectively guarded against.
Inspect the work site carefully prior to climbing or working on a tree to determine whether electrical lines pass through the tree or within your reach or that of other workers. All lines on utility poles should be viewed as possibly being energized, whether you think they are cable or telephone lines.
Branches hanging on energized powerlines should be removed only by qualified line clearance tree trimmers in the employ of the electric utility company and using approved insulated equipment.
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Underground Electrical Equipment
Workers should be aware of the location of ground mounted electrical facilities as well as overhead powerlines. Vehicles positioned for work should be kept clear of this equipment. Damage to the equipment may cause power outages and create electrical hazards for the tree workers.When planting or removing trees, workers should be aware of any underground utility cables buried in or near the work area. In fact, the Arizona Underground Dig-In Law requires anyone planning on doing excavation work to determine the location of all underground facilities. The Underground Dig-In Law also requires no excavation work to start until all utilities have been marked or determined not to be in the digging area.
Upon receiving your locate request, the utility companies will mark their underground facilities. This may take up to two working days so plan ahead.
Do not leave cables exposed. If the underground cable is nicked, cut, or strained in any way, call the utility company. Damage is not always obvious. Careful examination of the line may reveal minor damage that can be repaired, saving tear-up and replacement of newly completed work later on.
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Tree Spraying
Spraying operations near energized electrical wires or equipment may create safety problems. Spraying directed into overheated lines may damage equipment or cause arcing between wires. Electricity also may be conducted down the hose stream, creating a hazard for workers.Return to top of Working Near Power Lines
Electrical Emergencies
Strong winds, ice or unintentional contact with equipment may cause trees or tree limbs to fall into powerlines. This may cause wires to break and fall to the ground. Should this happen, notify the electric utility company immediately.A fallen wire can create hazards for workers and the general public. Objects touched by a fallen wire - fences, vehicles, buildings or even the surrounding ground - must be considered energized and should not be touched. It is impossible to tell simply by looking whether a downed wire is energized. Consider all downed wires energized and dangerous until the electric utility personnel notify you otherwise.
Where a power line has fallen across a vehicle, occupants should remain within the vehicle. If they must leave the vehicle because of a life-threatening situation, such as fire or potential explosion, they should jump clear of the vehicle without touching either the vehicle or wire and the ground at the same time. Once clear of the vehicle, they should shuffle away, taking small steps and keeping both feet in contact with the ground.
Remember...electricity can be transmitted from the victim to you. If a switch is accessible, shut off the power immediately. Otherwise, stand on a dry surface and pull the victim away with a dry board or rope. Do not use your hands or anything metal.
Use a CO2 or dry chemical extinguisher to put out an electrical fire. Water should be used only by trained firefighting personnel.
In an emergency involving power lines or electrical equipment, call the electric utility company and 9-1-1 immediately.
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