
1) Electric power distribution
Found on
https://www.crosswordclues.com/clue/overhead-line

An overhead line or overhead wire is used to transmit electrical energy to trams, trolleybuses or trains. It is known variously as: In this article the generic term overhead line is used, as used by the International Union of Railways. Overhead line is designed on the principle of one or more overhead wires (or rails, particularly in tunnels) situ...
Found on
http://en.wikipedia.org/wiki/Overhead_line

line with one or more conductors or a cable supported above ground by appropriate means NOTE 1 - An overhead line may consist of only one conductor when the circuit is closed by the Earth. NOTE 2 - An overhead line may be constructed with bare conductors, generally supported by insulators, or with insulated conductors. NOTE 3 - The concept of overh...
Found on
http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=151-12-33

an electric line whose conductors are supported above ground, generally by means of insulators and appropriate supports NOTE - Certain overhead lines may also be constructed with insulated conductors.
Found on
http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=466-01-02
No exact match found.