Sierra Pacific Power Company’s Tree Trimming Program is intended to help protect the public, protect property and maintain electric reliability. At Sierra Pacific, trees are a cause of power outages. Short circuits from branches rubbing against power lines, branch breakage and trees blown over during storms are just a few of the hazardous situations that can occur.
This information is also available in a downloadable brochure.
Safety
Tree trimming is an essential part of maintaining a
safe and reliable supply of electricity for your convenience.
Attempting to prune or climb a tree near power lines is dangerous.
Each year, hundreds of people throughout the United States are
injured or killed when they climb or prune trees. Power lines can
seriously harm children climbing in the branches.
Power lines broken by falling branches are extremely dangerous and may
cause fire, shock or electrocution. By trimming trees and brush we can eliminate
safety hazards and reduce tree-related outages.
Please remember that any trees interfering with utility power lines can lead to, or are, a dangerous situation.
Legislation
Because tree trimming is so important, legislation exists which requires both Sierra Pacific Power and the property owner to ensure that a minimum clearance space between trees and power lines is maintained.
- Why Does Sierra Pacific
Power Trim Trees?
Sierra Pacific Power 's Tree Trimming Program is intended to help protect the public, protect property and maintain electric reliability. Short circuits from branches rubbing against power lines, branch breakage and trees being blown over during storms are just a few of the hazardous situations that can occur. Tree trimming is an essential part of maintaining a safe and reliable supply of electricity. Attempting to prune or climb a tree near power lines yourself also can be dangerous. Each year, hundreds of people throughout the United States are injured or killed when they climb or prune trees. Concealed power lines can seriously harm children climbing in the branches.Power lines broken by falling branches are extremely dangerous and may cause fire, shock or electrocution. By trimming trees and brush we can eliminate safety hazards and reduce tree-related outages. Please remember that any trees interfering with utility power lines can lead to a dangerous situation. Because tree-trimming is so important, legislation exists which requires both Sierra Pacific Power and property owners to ensure that a minimum clearance space between trees and power lines is maintained.
- Why does Sierra Pacific
Power trim trees on private property?
Sometimes trees will grow into or near Sierra Pacific Power lines. Under these circumstances Sierra Pacific Power will trim branches to prevent damage and danger to the public and to the power lines from swaying branches. Sierra Pacific will also remove trees where the trunks are too close to the power lines.
- How much will Sierra Pacific Power Trim?
Near Distribution Lines - At the time of trimming, we will seek at least 10 feet of clearance between the high voltage Distribution power lines and tree limbs.
Near Transmission Lines -
Sierra Pacific Power will trim to the full extent of easement rights and work towards a "Wire Zone – Border Zone" practice as encouraged through Best Management Practices. In situations where an easement does not exist, Sierra Pacific will take into account Federal and State rules and regulations. The minimum clearance distances are: 115kV and less than 230kV – fifteen feet; 230kV and less than 345kV - twenty feet; 345kV and less than 500kV twenty-five feet; and 500kV and greater thirty feet. Additional important considerations in regards to clearance distances are line sag, as well as tree sway and line sway.
- Who does the work?
Sierra Pacific Power uses skilled and specially trained staff and selected contractors who have received training to meet the requirements given by OSHA and ANSI Z133.1-2000. - How often does Sierra Pacific trim trees?
Sierra Pacific Power typically trims on a circuit basis taking into account a variety of factors such as tree growth rates, last patrol date, line history and others. - How does Sierra Pacific trim trees?
At Sierra Pacific Power we follow the trimming practices recommended by The International Society of Arboriculture and described by Dr. Alex L. Shigo in his book, "Pruning Trees Near Electric Utility Lines: A Field Pocket Guide For Qualified Line-Clearance Workers. These practices are followed at Sierra Pacific
Power :- Techniques consistent with the practices of natural,
lateral and drop crotch trimming shall be utilized.
- Cuts are made back to a
main stem or branch of sufficient size. In no case shall deciduous tree
limbs be stubbed off at the edge of the clearing limits.
- Wherever possible, all trimming
cuts shall be made to direct future growth and sprouting away from the
conductors.
- Conifers should be trimmed
in a manner that allows them to retain as much of their natural shape
as possible.
- All dead branches overhanging
primary conductors at any height shall be removed.
- A minimum of cuts should
be utilized to achieve required clearances.
- Where practical, cuts should
be primarily restricted to large-diameter branches made well within
the crown. Shaping through the use of many small diameter branches in
the outer crown should be avoided.
- Remove living branches by
making cuts as close as possible to the branch collar. Remove dead branches
by making cuts as close as possible to the living tissues that surround
the dead branch at the base.
- Precautions shall be taken
to avoid stripping or tearing of bark when cutting
back
- Who has responsibility for
trees and power lines?
A minimum clearance space is required between power lines and equipment and any foliage. Inside the power corridors, tree trimming and removal is Sierra Pacific Power 's responsibility. Sierra Pacific Power will trim or remove trees outside the power corridor when these trees (dead or diseased) could interfere with or fall into the line and create a hazard.It is the property owner's responsibility to keep trees clear of their electric service line. This is the line that runs from the pole to the house. Sierra Pacific recommends the use of a trained tree trimmer to clear electric service lines. It is Sierra Pacific Power 's responsibility to keep trees clear of its power lines. The clearance space required increases as the voltage increases. Trees don't need to be touching the power lines to require trimming. They will be trimmed on a cycle if they are growing into the clearance space. Achieving the required clearance may mean trimming on your property.
back
- Who can I contact about tree trimming?
Please call the Vegetation Management Administrator at (775) 834-7986.
-
Why not just shape trees?
Shaping was once a popular practice for tree trimming, but it has now been learned that this is not horticulturally sound, as it can create a safety hazard to people, property and overhead lines. Shaped trees re-grow quickly with vertical suckers that sprout up from cut branch ends. The suckers are only weakly attached to the branches and are more likely to break off, even in only moderate winds, creating a greater problem of wind borne debris. Tree health may also be affected. This can lead to power blackouts and the need for far more frequent tree trimming. Proper trimming may look severe at first but trees will re-grow at a normal rate and are trained away from power lines. Tree health is maintained and even enhanced by correct cutting at the branch collar. - What can I do to help?
Customers can help reduce costs and maintain a pleasant environment by ensuring trees of the right type and size are planted near power lines. Remember "Right Tree, Right Place." Seek permanent solutions. Do not plant trees near electric lines; or plant only low-growing, compact varieties. The guidelines given here aim to reduce sprouting, reduce the working time in a tree for the tree worker, increase the time between pruning cycles, and help the trees planted near lines to be healthy, safe and as attractive as possible. It is better for the trees, lines and customers to remove fewer but larger branches at nodes. Nodes are where branches shed naturally. It will take time to make all the adjustments given here. But, if we all work together, the adjustments will come. And the public, customers, property, trees, and tree workers will all benefit.
