It is possible to change out splices in power lines while the line is energized. The procedure also improves the reliability of the splice.
A splice is usually pressed together using hydraulics while the line is down (see result in figure 1, left image).
But a company names Quanta replaces and redesigns the splice using implosion to enhance the quality and replace the old splice on-the-run. The high quality result can be seen in figure 1 below.
See a newscast of the procedure : (8,5MB .wmv file)
See a clip of power line workers from Quanta: (4,8MB .wmv file)