 workers because they contain very high voltage and are typically uninsulated. Contact with these lines are typically fatal. The most common cause of contact with power lines comes from the use of equipment, including cranes, backhoes, metal ladders, raised rough terrain forklifts, aerial lifts, metal building material, concrete pump trucks, raised dump truck beds, and scaffolding. Missing switch plates or receptacle covers around electrical outlets and missing covers on breaker boxes can lead to workers being exposed to live electrical parts and inadvertently making contact with it, so receptacle and switch covers must always be installed when there is live power to the outlets. Normal use of electrical equipment on construction sites causes wear and tear that can lead to exposed wires damaged.