Overhead lines insulation distance reduction due to stay wire´s expansion from ground fires

This is a theoretical and experimental investigation concerning the reduction of the insulation distance of distribution lines, when a stay wire (a steel wire that supports the pole of the distribution network) is heated by a ground fire. It has been experimentally proved that a ground fire can drastically reduce the mechanical strength of the stay wire, to a point where wire breakage can be caused even from a small ground fire resulting from dead wood and small bushes near the wire. Theoretical results lead to the conclusion that the fire causes a permanent expansion of the wire, which results in the loosening of the bare conductors and the reduction of the insulation distance.