An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy along large distances. It consists of one or more conductors (commonly multiples of three) suspended by towers or poles.


• The number of light levels recommended depends on the height of the structure;
• The number and arrangement of light units at each level should be placed so the lighting is visible from every angle in azimuth;
• Lights are applied to display the general definition of an object or a group of buildings;
• Width and length of buildings determine the number of lights installed at the top and at each light level.


High-intensity obstacle lights, Type B, should be used to indicate the presence of a tower supporting overhead wires, cables, etc., where:
a) an aeronautical study indicates such lights to be essential for the recognition of the presence of wires, cables, etc.; or
b) it has not been found practicable to install markers on the wires, cables, etc.

Where high-intensity obstacle lights, Type B, are used, they shall be located at three levels:
— at the top of the tower;
— at the lowest level of the catenary of the wires or cables; and
— at approximately midway between these two levels.

High-intensity obstacle lights, Type B, indicating the presence of a tower supportingoverhead wires, cables, etc., should flash sequentially; first the middle light, second the top light and last, the bottom light.