The hazard
A live wire looks exactly like a dead one, and your body can become part of the circuit. Electrical contact can cause shock, burns and electrocution, and even a small shock can make you fall from a ladder. How badly you are hurt depends on how much current flows, the path it takes through your body and how long the contact lasts.
The action
Look up before you raise a ladder, pole, scaffold section or long tool. If you are not qualified, the general industry rule says you and any conductive object you handle must stay at least 10 feet from unguarded, energized overhead lines of 50kV or below to ground. Higher-voltage lines need even more room. Treat every overhead line as live. (29 CFR 1910.333(c)(3)(i)(A))
ASK THE CREW
Where are we using temporary power on this job, and is every outlet we use GFCI protected?
From the talk: Electrical safety. Read it in full, free, with the questions and the sign-in sheet.