It's easy to prevent serious accidents involving cranes and power lines. Here's a few safety tips to keep in mind on the job:

Remember, it's the law. Many states like Virginia and North Carolina have a state law which requires that the operator/owner of a crane notify a utility or line owner at least 48 hours before they work in close proximity to any power line.
If your crane boom or mast contacts a power line, the operator should immediately try to swing the boom into the clear.
If it is necessary to leave the equipment, anyone on the machine should jump entirely clear of the unit. Jump so that both feet hit the ground at the same time, and keep them close together.
Walk away in a small-step shuffle because a lot of power flowing into the ground can create differences in electrical potential around the problem — enough differences to actually shock anyone whose feet are too far apart.
Once clear of the equipment, do not return for any reason until the power line has been grounded or determined to be safe by your electric utility or the owner of the line. Keep anyone nearby from touching or approaching the equipment.
A brochure (PDF file) about safety around power lines is available for downloading/printing in English and Spanish. Safety training information for first responders is also available.