Planting large trees near power lines can cause years of conflict between homeowners and Utility Service providers over issues such as maintaining power supply, aesthetics, safety and tree health. For safety reasons and to minimize power supply disruptions, Utility providers are obligated to keep power lines clear of growth within 10' of the line, both below the line and side to side.
When planting trees under a power line, the ultimate height at maturity should be 16' or less; trees planted near power lines should have a mature height of 25' or less.
The following is an outline of a variety of options, but is by no means an exhaustive list. In selecting the option that is right for your location, be sure to consider its cultural needs in addition to its mature height, such as hardiness, sun/shade preference, water needs, soil preference and tolerances.
In addition to small deciduous trees, you can also consider small conifers, large shrubs and pendulous or weeping cultivars that do not have a strong dominant leader, as they can be staked up to the appropriate height and left to ramble. If desired, some large shrubs can be trained to resemble small trees.
One final tip, be careful of the word 'dwarf' as it can be meaningless. ‘Dwarf’ is applied to any cultivar that is shorter in height than the parent it was derived from; it is not a determination that assures it will remain small.
Thanks to Michael A. Dirr's, Manual of Woody Landscape Plants for technical information.
Rocky Mountain Power has a booklet titled Small Trees for Small Places, by Randall Miller. It includes input from some great Utah Tree people, including Dick Hildreth and Dr. Mike Kuhns. It was created for use in multiple states, so be careful to look at hardiness zones for your area. To request your copy or to view on-line, go to http://www.rockymountainpower.net/ed.html and click on ‘tree planting and pruning’.