Power_line_safety

All power lines in Minnesota are designed and built to meet or exceed the standards of the National Electrical Safety Code and state safety requirements. While most everyday activities can be continued near a power line, common sense precautions should be observed. This informs you of safety precautions to be observed under or near a power line.

Please read this information carefully and save it for future reference. The items discussed are intended to be examples of activities that may or may not be carried out in the vicinity of a power line and should not be considered to be all inclusive. You can live, work and play safely adjacent to and under power lines provided you use common sense.

You should remember that any electrical installation, be it your household service or a power line, must be treated with caution and respect. If you have any questions about any of the information here, contact Great River Energy or your local electric utility (that is, where you pay your electric bill) for more information.

Q. How can farm equipment and other machinery be safely operated near power lines?

A. Farm equipment, passenger vehicles and trucks may be safely used under and near power lines. Power lines are designed to meet or exceed minimum clearance requirements over roads, driveways, cultivated fields and grazing lands specified by the National Electrical Safety Code (NESC). Great River Energy designs transmission lines to meet NESC and other safety requirements. Recommended clearances within the NESC consider a relative vehicle height of 14 feet. Although it may appear the line has clearance exceeding 14 feet, we advise you to contact your local electric utility or Great River Energy directly if you are considering operating a vehicle with a height greater than 14 feet. You can operate machinery safely near power lines if proper clearances are maintained between machines and the power line wires. But remember:

Physical contact with a power line wire is extremely hazardous and may cause a lethal shock. Equipment SHOULD NOT be operated under a power line in a manner that would cause contact or near contact with the wires.
DO NOT lift, elevate, build or pass under a power line any object, implement, facility or vehicle that could be expected to make contact or near contact with the wires.
To maximize safety against flashover or arcing, it is recommended that equipment, including antennas or people, should not come closer than 15 feet to any energized power line wire.
Equipment that can be extended, such as a stack mover or grain elevator, requires the utmost care when in the vicinity of a power line.

A. Vehicles used for farming and other purposes are effectively grounded through the tires. Modern tires provide an electrical path to ground because carbon black is added when they are produced and carbon is a good conductor of electricity. Metal parts of farm equipment are frequently in contact with the ground when baling, plowing or engaging in various other activities. Therefore, vehicles will not normally build up an electric charge under power lines unless they have unusually old tires or are parked on dry rock, plastic or other surfaces that insulate them from the ground. Should a vehicle build up a charge because of these conditions, it can be grounded by simply attaching to the vehicle a grounding strap long enough to touch the earth*. If you are in doubt about how and where to attach a ground strap, contact your local electric power supplier for more information.

A. The possibility of fuel ignition under a transmission line is remote. There have been no reported fires caused by sparks induced by power lines. However, refueling vehicles is not recommended under or closer than 100 feet for high voltage transmission lines operating at 200 kilovolt (kV) or greater.

The following information generally applies to higher voltage transmission lines of 200 kV or greater. Induced voltage in a building or a fence caused by smaller lines would be a rare occurrence.

A. Generally, buildings are not permitted within the easement. A building under a line may interfere with access to the line for maintenance and emergency repairs. A fire in a building on the easement could damage the transmission line. Also, a building may be closer to a line than electrical codes allow. Under special circumstances, Great River Energy may allow construction of buildings within its easements, but only if they meet certain standards.

Q. Are there any hazards to existing metal buildings after a power line is constructed?

A. Great River Energy designs transmission lines to meet or exceed safety codes. If you plan to construct, or have constructed, a metal building near a high voltage power line (200 kV or greater), or if you have concerns as to whether or not a building is properly grounded, contact your electric power supplier for information on proper grounding requirements.

A. Induced charges can build up on fence wires mounted on wood posts near power lines. This phenomenon is generally restricted to higher voltage lines (200 kV or greater). The magnitude of the buildup depends on a variety of factors:

Q. Are there different safety standards for nonelectric and electric fences?

Electric cattle fences, being specially insulated from ground, can pick up an induced charge from transmission lines. Usually, the induced charge will drain off when the charger unit is connected to the fence. When the charger is disconnected either for maintenance or when the fence is being built, a small shock may be produced. To prevent such a shock:

• One or more of the fence insulators should be shorted out to ground with a wire when the charger is disconnected.

• An electric filter may also be installed that grounds out charges induced from a power line while still allowing the charger to be effective. Information on fencing near power lines may be obtained from your electric power supplier. Irrigation

A. Irrigation is compatible with transmission lines as long as you take certain basic precautions:

Prevent a solid water stream from hitting the wires. Equipment with small diameter or fine mist spray nozzles presents no problems because the solid part of the water stream will not reach the power line wires. A broken-up spray of water will not conduct significant amounts of electricity. Even large diameter nozzles operating at their normal spray angle will not reach the wires with a solid stream. At no time should the solid part of a water stream touch power line wires. Should that happen, turn the water off by switching the pump off before trying to correct the problem. It is recommended that large nozzles be located at least 150 feet from the outside wires of power lines.
Make sure the irrigation system is well grounded. If the center pivot system is located or swings within the right-of-way, a simple cable-type material connection between the irrigation pipe and a suitable ground (for example, the main header feed pipe from the well) will adequately ground the system.
Maintain a safe clearance. Irrigation pipes should be unloaded at least 50 feet from power lines to avoid any chance of raising them too close to the wires.
DO NOT install long lengths of pipe parallel and adjacent to transmission lines. They should be laid out at right angles to power lines, if possible, to reduce induced charges.
With pipe-type systems, don¹t let the pipe touch the transmission lines.
In residential areas, there are no limitations on the operation of typical home sprinklers used for watering lawns and gardens, other than preventing a direct solid stream of water from contacting the transmission line.
Each system should be reviewed on a case-by-case basis. These precautions are necessary because of the potential of water and metal to conduct electricity. Fertilizers and pesticides tend to increase the conductivity of water, making extra precautions necessary. Questions regarding the installation and operation of an irrigation system adjacent to or under a power line should be directed to your electric power supplier.

Fires should not be started under a power line because they could damage the poles or wires and cause a power outage. It is also possible that the power line could flash over to the ground, through hot air and smoke, creating a hazard in the vicinity of the fire. Transmission Line Maintenance Strict transmission line maintenance standards are followed by Great River Energy. Line inspections occur on a regular basis. Ground inspection is normally made during the fall or winter months. If entry onto the easement area is necessary for these inspections, they will be minimal. Emergency inspections or repairs may occur at any time.

A. Except for the land beneath the structures themselves and their supporting wires, transmission lines take very little land completely out of use. However, to ensure safety and access to the line, Great River Energy has some land use restrictions.

A. Most recreational activities are compatible with transmission lines. Some require caution. Listed here are some hazards along with precautions.

Do not fly kites or model planes near any power line.
Always fly kites and planes so the wind carries them away from power lines, television and radio antennas.
Call Great River Energy or your electric utility if a kite or plane becomes snagged in a power line. DO NOT pull the string or climb a tower or pole to get it down.
If a plane is caught in the line, let go of the control line immediately and call your electric power supplier for assistance. DO NOT attempt to retrieve it yourself.

Never climb towers, fences at substations and switchyards, transmission lines or poles that serve your homes and farms.

Never touch a broken or downed wire. If you discover one, stay clear and call Great River Energy, your electric cooperative or the police or sheriff’s office.

Stay away from ALL tall objects during storms, such as transmission line towers and trees. They are dangerous because lightning tends to strike the highest point in an area and travels through it to reach the ground.

When working with tall equipment around power lines, LOOK UP!!! Know where the lines are and stay away from them.

For more information, contact your local electric utility or Great River Energy’s Land Rights Department.

If you see broken or damaged equipment or any other unusual condition on a transmission line, please report immediately to Great River Energy by calling: 1-800-442-3013.