Arc Protection During High Voltage Live Work

Abstract

The bare-hand technique is a common work method applied in high voltage power grids. Rules, guidelines, and recommendations must guarantee an appropriate level of protection against electric shock, electric field stress, open flames, and arc flash incident energy. Traditionally, conductive clothing has been used by line workers for protection against electric fields of extra-low frequency. Most conductive clothing designs offer high efficiency as Faraday-cages. Although screening efficiency of a well-designed clothing is high enough to significantly decrease electric fields for prevention against electric shock, other hazards should be addressed. Transmission line geometries may guarantee required clearances between conductive parts at different potentials. However, additional protection measures may be required. Several accidents occurred to line workers using hot sticks, insulating boom trucks, insulating scaffolds, and helicopters. During flashover, the incident energy of the arc may be high and exceed the threshold of a second-degree burn. This requires risk assessment and mitigation of arc flash and other thermal hazards. The most effective way of protecting against electric arcs is the integration of arc protective protection into conductive clothing. The improved design doesn’t compromise worker’s comfort. This paper presents an example on how to estimate arc incident energy for the transmission network of an electric utility, where protection from electric arcs and flames is mandatory. A procedure for selecting arc-rated conductive clothing is presented. The applications cover bare-hand work, and hot sticking.