On poles carrying both electrical and communications wiring, the electric power distribution lines and associated equipment are mounted at the top of the pole above the communication cables, for safety. The vertical space on the pole reserved for this equipment is called the supply space. The wires themselves are usually uninsulated, and supported by insulators, commonly mounted on a horizontal crossarm. Power is transmitted using the three-phase system, with three wires, or phases, labeled "A", "B", and "C".
