Automatic re-closers, found on both transmission and distribution lines, are programmed to re-energize dead power lines multiple times. Just like the circuit breakers in a substation, re-closers can cause a dead line to become live again. This is why you should always assume that all lines are energized (even fallen or low-hanging lines that may appear dead) unless you are otherwise notified.
Guy wires are cables that support utility poles against wind and weather. If a utility pole is damaged or if power lines sag low enough, guy wires can potentially become energized and pose an electric shock risk.