(f) 1[ " electric supply- line" means a wire, conductor or other means used for conveying, transmitting or distributing energy (whether by overhead line or underground cable), together with any casing, coating, covering, tube, pipe or insulator enclosing, surrounding or supporting the same or any part thereof, or any apparatus connected therewith for the purpose of so conveying, transmitting or distributing such energy and includes any support, cross- arm, stay, strut or safety device erected or set up for that purpose;]