Tree Trimming and Right-of-Way Maintenance Help Reduce Power Outages
Fallen trees and branches are a major cause of widespread power outages after a natural disaster. Electric cooperatives’ lines, poles and substation structures are engineered to withstand many forces of nature, but may not withstand the force of a fallen tree or large branch.
An aggressive tree-trimming and right-of-way maintenance program for power lines is crucial to the cooperatives’ mission of delivering reliable electric power to the consumer. However, even with a first rate right of way maintenance program, major storms often cause trees outside the right of way to make contact with the lines and cause outages.
A clear right-of-way is so important that a major financing source of rural electric cooperative infrastructure, the U.S. Department of Agriculture’s Rural Utilities Service (RUS), issues regulations and bulletins that, in essence, require electric cooperatives to have an effective tree-trimming and right-of-way clearing program in place. This program must include a regular rotation schedule determined by vegetation growth patterns and service area terrain. Similar tree-trimming and right-of-way maintenance programs are required for a cooperative to receive its safety accreditation from the National Rural Electric Cooperative Association (NRECA). All North Carolina electric cooperatives have earned their safety accreditation from NRECA.
In addition to using their own employees for right-of-way maintenance, many cooperatives employ contractors and tree-trimming specialists.
A guide to planting trees near power lines
Your cooperative can minimize expenses and let Mother Nature take her course if you consider power line clearance requirements before planting trees.
Consult your nursery salesperson to determine the mature height and width of trees before purchasing them.
The following trees are utility friendly when planted outside the right-of-way area:
| Utility-friendly trees | |||
| Crape myrtle | Dogwood | Eastern redbud | Japanese maple |
| Purpleleaf plum | Star magnolia | Yaupon | |
Measure 15 feet from the power line and then half the distance of the width of the tree’s spread when fully grown. This is as close as you should plant to power lines.
Try not to plant these tall growers within 50 to 75 feet of power lines:
| Tall-growing trees | |||
| Ash | Beech | Birch | Black gum |
| Cedar | Chestnut | Chinaberry | Elm |
| Maple | Oak | Pecan | Pine |
| Poplar | Southern Magnolia | ||
Clearance between trees and power lines
Graphics by Nicole Ferrari
Electric cooperatives adhere to national standards for safe, effective clearances in power line rights of way. Higher voltage power lines require a wider berth for clearance.
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Typical power lines and trees
Typical electric distribution lines that you see along the edge of roads
carry either 12 kilovolts or 24 kilovolts of pressure. The minimum clearance
between a power line and the closest edge of a tree is 10 feet for a 12-kv
line and 24 feet for a 12-kv line.
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Transmission lines and trees
The transmission lines you see extending across fields and up hillsides
carry higher pressure, either 69 kilovolts or 115 kilovolts. The minimum
distance between a transmission line and the closest edge of a tree is
50 feet for a 69-kv line and 100 feet for a 115-kv line.