Before you dig call the federally-mandated 811 to make sure there is not any buried power lines in your area. Do this before you dig holes for new trees, shrubs, fence posts, mailboxes or anything else. It is a good idea to call 48 hours before you plan to start your project. This is your responsibility under state law.
Always make sure you stay at least 10 feet away from the overhead power lines. Accidental contact could mean serious injury or death. Contact will also damage your equipment. Always have equipment lowered when transporting. When planting trees, remember they grow. A mature tree should be 10 feet away from a power line.