Trees Are Growing Close to an Electrical Transformer Box

Inclement Weather

• Power lines and above ground transformers are often damaged during inclement weather. High winds and ice can break branches damaging transformers for above and below ground power lines. Tree branches contain water and are electrically conductive. When branches from nearby trees strike the electric contacts of an above ground transformer they create a short that damages the transformer and interrupts service. Transformers for buried power lines are covered by an outer metal casing that prevents stray tree branches from creating a short circuit. However, the casing and internal components are still susceptible to damage from large, falling branches.

Planting Distance

• When you are planting new trees it is important to consider the size of the tree and its proximity to nearby power lines and transformers. According to Kansas City Power and Light small trees require at least 20 feet of separation between the planting site and power poles. Medium trees require 35 feet of separation and large trees need a minimum of 45 feet. Underground power lines are less vulnerable to damage from falling branches but still require at least ten feet of clear space around the transformer box for easy access during maintenance. Power companies may remove trees growing close to an underground power transformer if they impede access to the box.

Pruning

• Pruning trees growing near transformers and overhead power lines is a common method of preventing damage from falling branches. There are three basic pruning methods known as side trimming, V-trimming and crown reduction. Side trimming is used on trees growing alongside power lines. This technique prunes branches from the side of the tree growing towards the line to prevent branches from contacting transformers or lines. V-trimming prunes branches growing upwards from the center of the tree to prevent damage from trees directly below power lines. Crown reduction also removes the upper central branches of trees growing beneath power lines but it is limited to the upper most parts of the tree's crown. Pruning large branches growing around transformers is potentially dangerous and best left to professionals. Power companies often provide tree trimming services in these situations.

Other Considerations

• When planting trees around transformers or power lines you can use stakes and lines to secure trees in an upright position. This prevents young trees from bending and growing in the wrong direction. Species that are native to your area are more tolerant of inclement weather in your area than non-native species. Planting these species in areas around power lines will help prevent power outages and damage to transformers and power lines.