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
In general industry, live parts you may be exposed to must be deenergized before you work on or near them, unless the employer can show that deenergizing adds hazards or is not feasible because of equipment design or operational limits. Never assume a circuit is off because a switch is down or a light is out. If you are not trained and qualified for electrical work, stay out of panels and boxes. (29 CFR 1910.333(a)(1))
ASK THE CREW
Where are the overhead lines near our work, and what equipment or materials could reach them?
From the talk: Electrical safety. Read it in full, free, with the questions and the sign-in sheet.