P35.010: Live Line Working

Update The Live Working Reference Guide (The Tan Book): The Tan Book is a comprehensive technical resource on live working and includes fundamentals and principles related to live working tools, equipment, methods, and training resources. The guide is designed to be used by utility personnel engaged in any aspect of live work, from transmission maintenance managers and supervisors to line workers. An updated version of the guide is published each year including new or reviewed content based on input from project members.

Evaluate Live Working Rope: Dielectric ropes are used in live work along with rigid insulating tools. EPRI has initiated evaluations of the electrical and mechanical performance of multiple makes and models of dielectric ropes. These tests include existing standard methods as well as simulated real-world conditions. In 2027, EPRI intends to perform exploratory testing on ropes subject to load bearing applications, such as insulator changeout. Additionally, EPRI intends to perform tests on live working ropes under high relative humidity and rain conditions.

Perform Testing to Understand Insulating Tool Flashovers at Normal AC Voltages: Past industry insulating tool flashovers at normal ac system voltages have led EPRI to initiate a multi-year investigation to determine the root cause of the flashovers. Laboratory tests have been developed and performed based on hypotheses and/or numerical models to understand these occurrences. This research is part of a broader research effort that intends to investigate degradation and failure modes of insulating tools, research new materials to enhance tool performance, develop/search for new tool testing and inspection technologies, and develop reference and training materials that enhance worker safety in the use, inspection, testing, and care of insulating tools used in live work. In 2027, EPRI intends to continue with the full-scale electrical testing of the hot stick flashover case studied through Finite-Difference Time-Domain (FDTD) analysis previously developed. Additionally, EPRI intends to investigate the performance of insulating tool cleaning products available on market.

Perform Evaluation of Insulating Tool Care Products: This task aims to assess the effectiveness of commercially available cleaning/care products on insulating tools by evaluating their ability to remove contaminants and to block moisture buildup without degrading electrical or mechanical performance. The evaluation will consider changes in surface condition, dielectric properties, and long-term reliability after repeated cleaning cycles.

Evaluate Conductive Suits at High Current Conditions: This task aims to update and expand the investigation of conductive suits performed previously. It seeks to verify electrical performance of conductive suits available on the market, including shielding efficiency, current carrying capacity, and electric resistance degradation due to washing cycles. In 2027, EPRI intends to perform exploratory testing of conductive suits under high-current conditions and to incorporate results from electrical testing of utility-supplied conductive boots.

Evaluate Effects of High Temperature on Insulating Tools: This multi-year task seeks to identify mechanical and electrical effects on insulating tools, such as hot sticks and ropes, caused by contact exposure with conductors operating at high temperatures. This task is important as utilities have replaced conventional ACSR for HTLS conductors in order to increase the transmission capacity through higher temperature operation (up to 250°C). In 2027, EPRI intends to continue with exploratory tests on various insulating tools including load-bearing type insulating sticks and ropes.

Update the Minimum Approach Distance Calculator: This desktop software tool calculates and illustrates the minimum approach distance (MAD) for phase-to-ground and phase-to-phase clearances based on IEEE 516 and IEC 61472 formulae for utility-specific structures using line components and dimensions for that specific structure’s location. In 2027, EPRI plans to update the software with new features and bug fixes, and to continue the development of a new structure model builder. This new structure module seeks to enable the creation of custom structures, incorporating features such as underbuilt conductors, braced post configurations, and asymmetric crossarms.

Update the Minimum Number of Good Insulators Calculator: This desktop software, which is and add-on to the MAD Calculator, has been developed to assist in estimating the minimum number of good insulators for a safe live-line insulator changeout. In 2027, EPRI intends to update the software to include the option for calculating the minimum acceptable length of polymer insulators.

Evaluate Performance of Insulating Tools in Realistic Environments: This task intends to perform electrical testing of lightly contaminated FRP sticks exposed to realistic scenarios, such as the influence of high humidity and light fog, in both vertical and horizontal orientations.

Update Training Videos: This multi-year task seeks to review and update training videos related to induction hazards, temporary protective grounding, or equipotential zones to reflect evolving industry practices, standards, and field conditions, improving technical accuracy, clarity, and effectiveness for worker safety training. In 2026, EPRI intends to review and update the training video dedicated to fundamentals of temporary protective grounding of overhead transmission lines.

Provide Tools and Resources on The Transmission Resource Center: The following calculators, tools, result summaries, and references are planned to be available on the Live Working Transmission Resource Center: