Electric utility companies are responsible for delivering quality power as safely and inexpensively as possible, and sometimes trees can present a major obstacle to meeting those responsibilities. Power interruptions and safety hazards caused by trees can be avoided while preserving the tree's health and beauty by utilizing good tree pruning methods or the removal and replanting of the "right tree in the right place".

NAEC uses pruning techniques that are recommended by the International Society of Arboriculture, the American National Standards Institute, and the National Arbor Day Foundation. This means that vertical tree stems and horizontal branches are cut at the fork where the branch meets the trunk or other branches (see figure 1). This pruning method speeds wound closure, reduces sprout growth, and ultimately directs future limb growth away from the wires.  As a result, power outages are reduced and maintenance costs are lowered because properly pruned trees require less frequent pruning.

Before these new pruning standards were adopted, several pruners used the "tipping" or "topping" methods to prune problematic trees. Tipping involves the removal of the tips of the side branches of the tree (figure 2), and topping involves removing the top and upright branches of the tree (figure 3). Roundover occurs when the pruner uses tipping and topping to prune the tree into a rounded shape. These forms of pruning are discouraged because they lead to excessive sprouting, cracks, rotting, branch and trunk failure, and the premature death of the tree.

Another common problem that NAEC utility foresters encounter is the presence of large-growing trees near power lines. Many of these large trees must be pruned so heavily and frequently that they ultimately decline, decay, and come a hazard. The long-term solution to this problem is to select and plant trees whose mature height and spread will not interfere with nearby utility lines. Trees such as dogwoods, peach trees, and Japanese maples whose height does not exceed 15 feet at maturity are recommended, along with crape myrtles and other low-growing shrubs.

Finally, always ask the location of any underground utilities before planting a tree.  This is very important so that you do not accidentally dig into any lines and risk injury or service interruption. To find out if you're planting in a safe area, make the free phone call to 1-800-572-2900.