Try to trim a tree that is growing near electrical lines when the tree is as young as possible. The earlier you can start pruning the tree, the less likely it is to continue growing toward the power lines.
Look carefully at the tree that is growing near the electrical lines. Make note of which branches seem to be growing toward the electrical lines. These are the branches you will be trimming. This method is called directional pruning.
Follow the branches that are growing toward the electrical lines back toward the tree.
Prune the branch at the first crotch in the branches, or "V." Try not to prune branches at the trunk because this will promote decay and may harm the tree.
Use pruning shears that are extended on a pole to reach higher branches that are growing toward the electrical lines. Follow them back to the first branch crotch, as well.