Update the Inspection and Assessment Reference Book (The Yellow Book): This reference book is intended to be an evolving resource designed to become a single living repository of information on the inspection and assessment of overhead transmission lines. In 2026, EPRI intends to make updates in the reference book related to use of unmanned aerial vehicles for inspection of overhead transmission systems as well as new and emerging inspection technologies.

Update Inspection Field Guides: EPRI’s field guides provide personnel access to in-service inspection guidance for dozens of transmission line components with the convenience of remote access. As transmission line research advances, the knowledge related to inspection and assessment of various assets is identified and developed into a mobile field guide that provides a media-rich transfer of information that includes the asset condition and what actions to take. In 2026, EPRI intends to update the media content and update conditions assessment to reflect the most recent learnings and improve the accessibility and relevance of the guides.

Evaluate New and Emerging Inspection Technologies: This task focuses on inventorying and evaluating the efficacy, practicality, and application of new and emerging inspection technologies. EPRI plans to monitor all new technologies on its Tech Radar website as well as evaluate the early fault detection (EFD) technology developed by IND.T which utilizes radio frequency sensors and advanced analysis to detect and locate failing assets.

Develop Training Database for Artificial Intelligence Image Processing: Utilizing artificial intelligence (AI) to accelerate the processing of images from visual inspections is one method to increase the efficiency and decrease the cost of inspection of overhead transmission systems. One of the challenges with AI image processing is the lack of good data to train models. EPRI plans to gather and classify as many overhead transmission inspection images and datasets as possible to aid the training of AI models.

Develop an Asset Reliability & Availability Model: This task focuses on the development of an Asset Reliability and Availability Model for overhead transmission lines with a specific focus on the selection of appropriate maintenance regimes. Many utilities face the challenges of aging infrastructure and how best to handle the end of life of these assets. This model aims to use historic data as well as various other utility inputs to guide users to a selection of an appropriate maintenance practice per asset.

Host an Inspection, Assessment, and Maintenance Workshop: This task is aimed at enhancing the knowledge and skills of professionals involved in the inspection and maintenance of overhead transmission systems. This workshop will provide participants with insights into best practices, emerging technologies, and methodologies for effective assessment and maintenance of transmission assets. By bringing together industry experts and utility representatives, the workshop will facilitate discussions on challenges faced in the field, share lessons learned from past experiences, and promote collaboration among utilities to improve overall safety and reliability in power delivery. Participants can expect to gain valuable information that will aid in making informed decisions regarding their inspection and maintenance strategies.

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

• The Inspection and Assessment Reference Book (The Yellow Book)

• Overhead Transmission Line Asset Management Model

• Assessing the BATCAM’s Ability to Detect Corona

• Transmission Inspection Practices and Information Management

• Selecting Effective Inspection and Assessment Methods and Technologies

Develop New Metric to Quantify All-Aluminum Conductor (AAC), Aluminum Conductor Alloy Reinforced (ACAR) Conductor, and All-Aluminum Alloy Conductor (AAAC) Corrosion: Aluminum strand degradation may occur due to intergranular corrosion and manifests itself as exfoliation, resulting in a brittle aluminum strand. Preliminary research has shown that a comparison of tensile strength and torsional strength may provide a reliable metric for determining remaining service life of an all-aluminum conductor. The goal of this task is to understand and categorize the severity of aluminum strands degradation in terms of this new metric, correlate that metric with service life, and use that information to select where all-aluminum conductor performance will be maximized. The work performed under this task was started in 2025, and a report on the findings is anticipated in 2026.

Perform Assessment of Degraded or Failed Conductors, Shield Wire, and Hardware from the Field: EPRI intends to continue to perform evaluations of aged and failed conductors, shield wire, and hardware and add the results to the annually published Conductor Corrosion Condition Assessment report. Inspection of degraded and failed components from the field increases the industry’s knowledge on degradation mechanisms of components as well as contributes to improving inspection and assessment methodologies and techniques. This report intends to increase transfer of knowledge to increase the understanding of how conductors degrade and the environments that caused the degradation. EPRI intends on publishing an updated Conductor Corrosion Condition Assessment report in 2026.

Develop Guidance on Selection of Conductors for Severe Service Environments: EPRI intends to continue the development and update the end-of life calculator for aluminum conductor steel-reinforced (ACSR) and aluminum conductor steel-supported (ACSS) conductors that incorporates the effects of conductor attributes and the surrounding environment corrosivity to determine the conductor’s estimated lifespan. This information may be utilized by a utility to prioritize conductor inspection and select the right conductor for a specific location. EPRI intends on updating the web-based calculator in 2026.

Update the Corrosion Management Reference Book (The Rust Book): This reference book contains asset management information for inspection, assessment, mitigation, and remediation of corrosion on transmission lines. The guidebook contains the fundamentals of corrosion, guidance for inspection and assessment, and an understanding of mitigation methods that align with the environment. Future sections are intended to be developed specifically to support underground transmission, substations, and distribution. EPRI intends to publish an update in 2026.

Quantify Shield Wire Corrosion: Several types of shield wire (including optical ground wire (OPGW)) are available to utilities that utilize different designs and materials. EPRI intends to catalog shield wires available and evaluate their corrosion properties and resistance to different contaminants. The goal of this task is to estimate the lifespan of specific shield wires in specific environments. EPRI intends on publishing a technical update report in 2026 on the findings.

Identify and Evaluating New and Emerging Conductor Corrosion Inspection Technologies: EPRI intends to monitor new and emerging conductor corrosion inspection technologies coming out in the market that can be of potential interest for our members. EPRI intends on cataloging new and emerging conductor, shield wire, and hardware corrosion technologies in The Rust Book in 2026.

Host a “Design for Extreme Environments” Workshop: EPRI has interacted with utilities that operate transmission assets in extremely corrosive environments. There is potential value in understanding the performance of hardware, structures, and components subjected to such conditions. EPRI plans to host a workshop/information sharing session in 2026 in collaboration with P35.008 (Line Resiliency) and P35.003 (Structure and Foundation Corrosion Management), to facilitate mutual understanding of potentially useful countermeasures for extreme environments.

Provide Tools and Resources on the Transmission Resource Center: The following calculators, tools, result summaries, and references are planned to be available on the Conductor, Shield Wire, and Hardware Corrosion Transmission Resource Center:

Update Fleet Management Tools to Account for Topography, Surface Water, and Groundwater Fleet management encompasses an understanding of environmental conditions and asset characteristics to determine the best methods to select, apply, inspect, assess, and maintain subgrade assets and structures. In 2026, EPRI intends on improving corrosion prediction capabilities by incorporating the effects of topography, surface water, and ground water in the soil corrosivity maps and models. Additionally, EPRI intends on describing these changes and how to apply these tools to specific locations and assets in the Fleet Management and Effects of Topography and Groundwater report.

Develop a Web Calculator for Steel Pole Strength Loss Utilization ratios are a critical metric for understanding if a steel pole is a reject due to corrosion damage. This task intends to provide a health assessment tool in the form of a web-based calculator for asset managers, engineers, and maintenance personnel to determine if the structure is degraded. This structure health calculator requires inspection data for the corrosion damage, structural loading criteria, structure design data, and environmental data for the soil corrosion rates. EPRI intends on publishing this web-based calculator on the Transmission Resource Center in 2026.

Develop Method to Quantify Stray Direct and Alternating Currents EPRI is developing a novel method for measuring stray and circulating currents by measuring changes in soil resistance with current injection. This method may be significantly affected by different soil types. In 2026, EPRI intends on evaluating this technique with variety of soil types to quantify the effect and update the Managing Structural Degradation Due to Stray and Circulating Currents report.

Develop a Cathodic Protection Web Application In 2026, EPRI intends on migrating guidance on designing, installing, and applying cathodic protections into a web-based tool available on the Transmission Resource Center.

Investigate Degradation of Anchors and Helical Piles This task explores the mode of failure for various anchor designs and helical piles to determine if that anchor is at risk due to stray or circulating current corrosion. This task is based upon new learning that will allow utilities to understand why anchor systems degrade and how to mitigate that corrosion. EPRI intends to focus research in 2026 on understanding circulating and stray currents in high soil resistivity and high groundwater levels and publish the Anchor Management Guidelines.

Update the Corrosion Management Reference Book (The Rust Book) This reference book contains asset management information for inspection, assessment, mitigation, and remediation of corrosion on transmission lines. The reference book contains the fundamentals of corrosion, guidance for inspection and assessment, and mitigation methods that align with environmental conditions. EPRI intends on adding a new chapter focused upon the development and operation of the EPRI-developed Corrosion Monitoring System (CMS) in 2026.

Evaluate New and Emerging Coating Systems for Atmospheric, Subgrade, and Marine Service Each year, EPRI evaluates new and emerging coating systems for addition to the coating library. Many of these coating systems are designed for application in a manufacturing facility, but many are also designed for repairs in the field. The value that utilities receive from this task is the ability to select a coating system for optimal performance in their service territory. EPRI intends to update the web-based Coating Selection and Application tool in the Transmission Resource Center.

Host a “Design for Extreme Environments” Workshop EPRI has interacted with utilities that operate transmission assets in extremely corrosive environments. There is potential value in understanding the performance of hardware, structures, and components subjected to such conditions. EPRI plans to host a workshop/information sharing session in collaboration with P35.002 (Conductor, Shield Wire, and Hardware Corrosion), and P35.008 (Line Resiliency), to facilitate mutual understanding of potentially useful countermeasures for extreme environments.

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

Identify Methods for In-Service Conductor Identification: In 2026, new and emerging conductor and connector inspection technologies are expected to be identified, reviewed, and evaluated. Some utilities struggle to identify conductors that have been on their system for decades. EPRI intends on evaluating methods and tools to identify in-service conductors and update the Traditional Conductor and Connector Inspection Guide with their findings.

Analyze Failed or Removed-from-Service Conductors and Connectors: Conductors and connectors that have failed in service or have been removed from service are evaluated in the laboratory to better understand aging and failure modes. Tests may include resistance measurements, thermal responses, infrared (IR) measurements, radiographic analysis, and dissection or mechanical tensile testing to failure. EPRI aims to include and track this information in a database to identify trends in the industry. In 2026, EPRI plans to continue evaluating aged and failed samples and update to the report Evaluation of Aged Traditional Conductors and Connectors.

Continue Accelerated Aging of Single-Stage Compression Fittings at 93°C: EPRI has provided guidelines to assist utilities with the inspection and management of line connectors based on previous EPRI empirical testing of traditional conductors and connectors. Recently, manufacturers have developed new single-stage compression connector designs for traditional conductors, however, their long-term performance is unknown. In 2026, EPRI intends to continue the accelerated aging of newly developed single-stage compression fittings for traditional conductors at 93°C to understand their performance and degradation mechanisms over a simulated 40-year lifespan.

Provide Guidance on Inspection and Assessment of T-Tap Connectors: Guidelines help to assist utilities with managing connectors through their lifetime, including scheduling of inspections, selection inspection methods, data collection and use, prioritizing, and mitigation strategies. In 2026, EPRI intends on detailing inspection methods and acceptance criteria for T-tap connectors in the Traditional Conductor and Connector Management Guide.

Evaluate the Effects of Joint Compound Application in Compression Connector Performance: Accelerated aging at 93°C of test lines assembled with different amounts of joint compound is to be continued into 2026 to evaluate the impact of joint compound on the thermal and electrical performance of two-stage compression connectors. In 2026, thermal-mechanical aging is anticipated to finish on the two-stage compression fittings with different amounts of joint compound applied, and post-accelerated aging evaluations are planned. An update to the Effects of Connector Compound Application in Overhead Transmission Compression Connector Performance report is anticipated.

Provide Training on Traditional Conductors: With the loss of experienced personnel, it is imperative that we educate and train new personnel efficiently and effectively. In 2026, EPRI intends on providing new training introducing different types of traditional conductors, their degradation mechanisms, inspection techniques, acceptance criteria, and mitigation methods.

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

Develop Guidance on Accounting for Fiber-Reinforced Polymer (FRP) Degradation: Over the last several years, EPRI has been producing an application guide for composite structures built upon research performed in this project. The guide covers topics such as composite pole and crossarm manufacturing, degradation modes, installation, maintenance, and more. In 2026, EPRI intends to update the Composite Structures Application Guide focusing on the degradation of FRP composite materials. An emphasis will be placed on how engineers can account for material degradation to ensure reliable performance.

Develop Guidance from Ductile Iron Strength Testing: EPRI is undergoing a multi-year effort to develop the Ductile Iron Structures Application Guide for utility engineers. In 2026, EPRI intends to update this guide focusing on the findings from full-scale pole breaks as well as a detailed overview of the ductile iron manufacturing process.

Test Effects of Composite Material Outdoor Exposure: In 2026, EPRI plans to kick off a multi-year effort to understand the real-world aging of FRP composite materials subject to ultraviolet radiation and moisture. EPRI has done extensive research on FRP aging in an accelerated laboratory environment, but correlations to outdoor exposure durations remain difficult. This initiative seeks to close the gap between real-world and accelerated aging of FRP materials, providing insights to transmission engineers on expected lifespans of FRP composite poles. Photo courtesy of Q-Lab.

Perform Mechanical Tests on Accelerated Aged Composite Crossarms: For the last three years, EPRI has been engaged in accelerated aging of FRP composite crossarms at its laboratory in Lenox, Massachusetts. The target three-year aging cycle is set to finish in 2026. Upon completion, EPRI intends to subject the crossarms to full-scale mechanical testing.

Provide Cost Comparisons for Different Pole Types: This multi-year research effort is focused on helping engineers make the best decisions with regards to transmission pole material selection between wood, steel, concrete, fiber-reinforced polymer, and ductile iron. The Optimal Pole Material Selection Guide contains a qualitative review of each material type, representative structural designs, and pertinent design recommendations. In 2026, EPRI plans on updating the guide to include cost estimates for each material type to include procurement and installation expenses.

Provide Ductile Iron Transmission Structure Basics Training: While ductile iron poles are becoming more common in the transmission industry, many utilities are unaware, or lack the knowledge base for implementation. This training course, in partenrship with EPRI U4T, will cover the basics of ductile iron transmission structures. Course topics may include material fundamentals, manufacturing, design process, and installation recommendations.

ProvideTools and Resources on the Transmission Resource Center: The following calculators, tools, result summaries, and references are planned to be available on the Ductile Iron & Composite Structures Transmission Resource Center

Develop a Lightning Attraction Model Utilizing LiDAR Data: Lightning performance calculations are usually done on a line considered in an open terrain, which leads to conservative results for shielding failures. Typically, there are trees and objects on the sides of transmission lines, which help to reduce the shielding failure flashover rate. The TFlash module, within TLW-Gen2, allows to handle trees considered as boxes on the sides of the line model. Nevertheless, adding a precise description of the sides of a line when studying a poorly performing line is time consuming. EPRI is developing a method to use LiDAR data to evaluate the effects of trees and objects on the shielding failure rate. In 2026, EPRI intends to apply this method to a specific transmission line to identify limitations and potential improvements of the approach and publish their findings in the report Using LiDAR Data to Estimate the Shielding Failure Performance of Existing Lines.

Evaluate Electromagnetic Survey Methods to Estimate the Soil Resistivity: Unanticipated grounding electrode improvements are both costly and time consuming when constructing a new transmission line. A good estimation of the soil resistivity along the line during the planning phase of the project is necessary to correctly select a ground electrode design. Advances in electromagnetic surveying could speed up the process dramatically compared to Wenner surveys more typically used by utilities. In 2026, this task intends to continue the benchmark started in 2025, but focusing on identifying the limits of the different methods on several known simulated soil configurations. EPRI intends on publishing their findings in an updated report, Electromagnetic Survey Techniques to Estimate the Soil Resistivity.

Evaluate the Use of Ground-Penetrating Radar to Assess Existing Buried Electrodes: Ground-penetrating radar (GPR) is a noninvasive method in geophysics. It is classically used to detect the presence of pipes or cables buried in the ground to prepare road works and identify potential risks before digging. EPRI intends to evaluate if GPR could be used to identify the type of grounding electrode design buried in the soil without digging and used to locate counterpoises and check their electrical continuity. In 2026, EPRI intends to share their understanding of the technology and results from a preliminary field demonstration in a report, Using Ground-Penetrating Radar to Assess Existing Buried Electrodes.

Test Lightning Impulse Performance of Polymer Brace Post Insulators: In 2026, EPRI intends to continue testing the lightning performance of brace post insulators to develop a formula to estimate their lightning impulse strength including a unique flashover path. The results of these tests are intended to be published in the Lightning Impulse Tests on Brace Post Insulator Configurations report.

Update the Lightning and Grounding Reference Book (The Gray Book): The Gray Book was developed to be a single resource that consolidates fundamental learnings from decades of research in the area of lightning performance and grounding. To facilitate understanding of content contained in The Gray Book, calculators have been developed and are housed on The Transmission Resource Center. In 2026, The Gray Book will be available on The Transmission Resource Center and the chapter on surge arresters will be updated.

Update the Transmission Line Workstation—Generation 2 (TLW-Gen2): Lightning Performance and Power Frequency Grounding Modules: In 2026, these modules will be updated to incorporate the latest research results and correct any software and usability issues.

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

Update the EPRI AC Transmission Line Reference Book - 200 kV and Above (The Red Book): EPRI plans to commence an update of Chapter 13 - Considerations for Inspection and Maintainability. This update aims to enhance inspection and live line maintenance of advanced overhead transmission lines with new technologies, methodologies, and best practices. It includes improvements in materials, techniques, and structural design for safe and efficient inspection and maintenance.

Update the EPRI Transmission Line Reference Book: Conductor and Structure Motion (The Orange Book): Minor (editorial) updates are expected on The Orange Book in 2026, which will be released for the benefit of new members.

Update the EPRI Transmission Line Reference Book: 115–400 kV Compact Line Design (The Blue Book): Minor (editorial) updates are expected on The Blue Book in 2026, which will be released for the benefit of new members.

Add Cost Estimates to the Optimal Pole Material Selection Guide: This multi-year research effort is focused on helping engineers make the best decisions with regards to transmission pole material selection between wood, steel, concrete, fiber-reinforced polymer, and ductile iron. The guide contains a qualitative review of each material type, representative structural designs, and pertinent design recommendations. In 2026, EPRI will focus on producing cost estimates for each material type to include procurement and installation expenses.

Develop Best Practices for LiDAR Data in Overhead Line Design Software: With the proliferation of a wide range of LiDAR-capturing methods (including traditional airborne, uncrewed aircraft system (UAS)-based, and land-based platforms) there is scope for improved specification development to ensure optimal integration with line design software for new construction, increased power flow, vegetation management, and structure evaluation applications. In addition, artificial intelligence (AI) methods show promise in automated point cloud classification as well as digital twin development. In 2026, EPRI intends to begin evaluations on these new and emerging techniques.

Develop Safe Design Tension Limits of ACSS Conductor: Determining a safe conductor tension is a multi-faceted problem that requires understanding of the self-damping performance and fretting fatigue endurance of a conductor. This new initiative, which is a collaborative effort with project 35.015, aims to help solve this problem for aluminum conductor steel-supported (ACSS) conductor, as its self-damping and fatigue properties vary significantly from aluminum conductor steel-reinforced (ACSR) conductor. In 2026, EPRI intends to continue empirical testing on conductors to define tension limits.

Provide Orange Book Overview & Single Conductor Aeolian Vibration Training: EPRI aims to continue the production of selected training modules covering key chapters in The Orange Book. These events will be held in conjunction with EPRIU4T.

Provide Training Workshop on Lattice Tower Design: The advent of renewed 765-kV expansion has placed emphasis on steel lattice tower design, which is a support option facing skill depletion as more utilities adopt steel poles as a preferred support solution. EPRI aims to enhance skill in lattice tower design by hosting a workshop which covers essential elements of lattice tower design and effective modelling and optimization of lattice towers.

Produce a NESC Clearances Calculator: EPRI aims to produce an advanced calculator to automate the calculation of National Electric Safety Code (NESC) transmission line clearances as defined by NESC Rules 231–239. This versatile tool will accommodate a wide range of clearance scenarios and voltage levels, including both baseline tabulated clearances and alternative clearance calculations. The 2026 version of the calculator will be available in an Excel-based format, tailored for the 2023 NESC. It will serve as a valuable training tool and informational resource for transmission engineers.

Update the Optimal Line Tension Calculator (Op10): Op10 software is designed to determine the most cost-effective installed conductor tension, based on specific project variables, and to quickly determine the impact of a selected (or existing) conductor tension. Op10 will be updated to include new features as requested by users.

Update the Transmission Line Workstation Gen 2: Design and Vibration Module: This EPRI software tool was developed to facilitate engineers in evaluating different design options effectively. Algorithms in some of the design programs may require updating based on EPRI research. Updating of this software may also be required to improve user features, add new functionalities, or to be compatible with other industry software used by the design engineers.

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

Quantify Transverse Cascading Loads: While EPRI and other institutions in the transmission industry have conducted research into longitudinal cascading events, transverse cascading loads remains a knowledge gap. EPRI aims to build and operate a transverse cascading test line to quantify loads experienced by structures during these events and ultimately help engineers design against them. In 2026, EPRI aims to install a test line and perform exploratory tests to simulate transverse cascades to then execute upon in subsequent years.

Develop Design Guidance to Prevent Phase-to-Phase Flashover Resulting from Asynchronous Conductor Movement: When spans are long or phases are horizontally compacted, utilities have experienced phase-to-phase flashovers during gusty wind conditions. There is very little guidance on how this problem should be avoided. EPRI aims to vet previously proposed design techniques and will examine past wind tunnel research and climate data to determine an appropriate design technique to prevent phase-to-phase flashovers.

Produce Enhanced Climate Risk Maps: Significant value can be obtained by exploring climate data as it relates to weather events impacting the structural and electrical reliability of overhead lines. EPRI intends to leverage new and existing climate data to produce a range of enhanced climate risk maps for specific weather events.

Derive Lessons from Failure: With every structural or mechanical failure event, there is a potentially valuable lesson to be learned by line design engineers. Very often the events leading to failure are often multi-dimensional. When the root causes and possible preventative actions from these events are documented, they can teach engineers how to become better designers. In 2026, EPRI aims to add multiple case studies to its current guide on documented failures related to how structures have failed in the past and how future generations of engineers may use this information to achieve more resilient designs.

Rapid Response Emergency Tower: The Rapid Response Emergency Tower was developed under EPRI’s Technology Innovation Program in support of project 35.008. In 2026, EPRI aims to compile instruction manuals and finite element modeling (FEM) models for various configurations in order to facilitate applications to various restoration scenarios.

Host a “Design for Extreme Environments” Workshop: EPRI has interacted with utilities that operate transmission assets in extremely corrosive environments. There is potential value in understanding the performance of hardware, structures, and components subjected to such conditions. EPRI plans to host a workshop/information sharing session in collaboration with P35.002 (Conductor, Shield Wire, and Hardware Corrosion) and P35.003 (Structure and Foundation Corrosion Management), to facilitate mutual understanding of potentially useful countermeasures for extreme environments.

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

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 2026, EPRI intends to perform additional exploratory testing and issue a technical guide on inspection and retirement of ropes intended for energized work.

Evaluate Portable Hot Stick Testing Devices: Hot stick handheld field testers are used to determine if fiber-reinforced plastic (FRP) sticks are electrically safe for contact with energized lines prior to work. Many utilities have questioned the detection effectiveness of such devices. This task intends to identify the commercially available testers and conduct tests to evaluate their performance. In 2026, laboratory testing results of some of these devices (e.g., Hubbell Wet/Dry Hotstick Tester, Hastings Hot Stick Tester, PENTA TTr2) are intended to be presented in a report.

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 2026, EPRI plans to update the software with new features and bug fixes, and to start the development of a new structure model builder. This new structure module is to be designed to enable the creation of custom structures, incorporating features such as underbuilt conductors, braced post configurations, and asymmetric crossarms.

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 2026, EPRI intends to conduct full-scale electrical testing of the hot stick flashover case studied through finite-difference time-domain (FDTD) analysis previously developed. Additionally, EPRI intends to issue a test report. These small and full-scale test results are planned to be published in the EPRI report, Understanding Insulating Tool Flashovers at Normal AC Voltages.

Evaluate Conductive Suits: 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 2026, EPRI intend to include the investigation of conductive suits intended for ac induction.

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 aluminum conductor steel-reinforced (ACSR) for high-temperature, low-sag (HTLS) conductors in order to increase the transmission capacity through higher temperature operation (up to 250°C).

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 high humidity and light fog, in vertical and horizontal positions.

Host an Overhead Transmission Line (OHTL) Temporary Protective Grounding and Bonding Workshop: EPRI intends to host a two-day workshop on temporary protective grounding and bonding practices including laboratory demonstrations at its high-voltage laboratory facility in Lenox, Massachusetts.

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:

Perform Multi-Stress Aging Tests: For over two decades, EPRI’s multi-stress aging chamber has provided utilities with timely information about the performance of polymer insulators, significantly reducing the time needed compared to in-service experience alone. The chamber remains a valuable asset, and as some components are removed for evaluation, EPRI plans to add new designs that reflect industry trends.

Perform Small-Scale Degradation Tests: EPRI has developed several small-scale degradation tests that are repeatable, reproducible, and relevant for assessing an insulator’s performance under specific in-service conditions. EPRI intends to continue monitoring the aging of samples, refine the test methodology, and report on the findings.

Update E-Field Modeling Software: Recognizing the critical role of electric fields in the service life of polymer insulators, this software calculates the electric field on new or existing insulator designs, helping utilities determine the need for corona rings. EPRI works with user feedback to keep this tool user-friendly and relevant.

Refine Polymer Insulator Impulse Testing Methodology: This task intends to refine the method of performing steep impulse testing on polymer insulators.

Update the Insulator Reference Book (The Violet Book): This comprehensive guide provides state-of-the-art information on insulator selection, inspection, and maintenance. Revisions to the book aim to include the numerous mechanical considerations when selecting insulators for different configurations.

Update the ADSS Application: This web-based tool helps users understand the electric field influence of high-voltage transmission lines on all-dielectric self-supporting (ADSS) installations. EPRI continues to improve user accessibility.

Develop Handling Test Methodology: These tests supplement performance tests by identifying polymer insulators that resist handling damage while meeting in-service performance needs. EPRI is developing a test protocol based on several years of test development.

Develop Nondestructive Weathershed Bonding Assessment Method: This task evaluates the use of ultrasound technology and nondestructive stress application to detect poor weathershed bonding in polymer insulators. EPRI aims to expand the dataset across multiple makes and designs to verify the test method.

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

Develop Porcelain and Glass Insulator Vintage Guide: Given the industry’s extensive history with porcelain insulators, assessing and managing these aging populations will be necessary for many years. However, test data alone are not sufficient for end-of-life decisions. With the increasing use of glass insulators, this task will develop a guide that consolidates essential information to help utilities assess failure risk and determine when to replace insulator populations based on their make and vintage.

Evaluate the Performance of RTV-Coated Insulators: Manufactured RTV-coated glass insulators are relatively new and have limited global experience. This task aims to evaluate the performance of RTV coatings in various service environments and assess if tasks such as cleaning can be used without damaging the coating.

Study Glass Insulator Failure: As glass insulators become more common, reports of shattering may increase. Tools to understand the causes of shattering can expedite issue resolution. EPRI intends to build on existing data to develop methods for determining the causes of glass insulator failures.

Evaluate Steep Impulse Flashover Test Methodology: There is some indication that glass quality may be assessed with steep impulse flashovers. EPRI intends to test utility samples of new glass insulators to understand how impulse testing can be used for this assessment.

Update the Insulator Calculation Engine (ICE): With the emergence of RTV silicone-coated glass insulators, controlling corona to reduce RTV degradation becomes crucial. This tool helps calculate electric field stress along an insulator string to determine the need for grading devices. EPRI continually updates this tool based on user feedback to ensure ease of use and relevance.

Insulator Reference Book (The Violet Book): This comprehensive guide provides state-of-the-art information on insulator selection, inspection, and maintenance. Revisions to the book aim to include the numerous mechanical considerations when selecting insulators for different configurations.

Provide Tools and Resources on The transmission Resource Center: The following calculators, tools, result summaries, and references are planned to be available on the Glass and Porcelain Insulator Transmission Resource Center:

Apply Novel and Emerging Technologies: There are many providers in the grid-enhancing technologies space (GETs). EPRI routinely identifies the newest technologies and updates to existing technologies to increase member awareness. With the number of dynamic line rating (DLR) technologies increasing, it can be challenging to understand how to construct a pilot project, how to leverage a pilot to phase into operational use, and how to scope timelines and budgets. As part of 2026 efforts, the ratings team will provide recommendations based on lessons learned from multiple field evaluations with U.S. utilities.

Measure Emissivity and Absorptivity of Conductors from the Field: For line ratings, LiDAR modeling, and infrared (IR) inspection, it is important to have accurate numbers for conductor emissivity and absorptivity. These values are often assumed; however, EPRI has developed tests that can directly measure samples provided by utilities that are new or removed from service. In 2026, an update will be provided on test results and the potential cost/benefit tradeoffs of coatings from a ratings perspective.

Outline Benefits and Drawbacks of Increased Power Flow Scenarios: Utilities face many challenges in getting upgrades and new construction projects accepted. This task maps different upgrade scenarios to the challenge areas such as corona loss, electric and magnetic field (EMF), cyber security, etc., to aid engineers in identifying “least-regrets” options when considering upgrades to existing lines. A 2025 report addressed cyber security; 2026 research will focus on EMF challenges that occur based on different types of upgrade/uprating including the linkage between EMF and right-of-way width.

Document Uprating for Unique Scenarios: Data Centers, Storage, and Renewables: This task leverages existing EPRI learnings and upcomong utility projects to scope potential issues with unique capacity demands or unique upgrade types. While this can encompass a large range of challenges, the focus for 2026 will investigate the challenges of uprating existing lines to accomodate the high energy demand from data centers and AI.

Update The Platinum Book : The Increased Powerflow Guidebook (The Platinum Book) is updated annually and covers all aspects of uprating. The guide covers overhead lines, underground cables, substations, transformers, and the economics of staged upgrades. As part of this task, EPRI collates materials from published EPRI reports and industry standards for power flow such as IEEE, IEC, and CIGRE. For 2026, EPRI plans to update discussions of CIGRE TB 601 ensure sections for both twisted pair and coated conductor are brought up to date.

Document Grid-Enahancing Technologies Field Trials: Many utilities are working with EPRI to pilot an emerging technology, such as DLR sensors, to get hands-on expereince with the new tools and practices. EPRI collaborates with members to provide guidance, capture lessons learned, and provide data needed to do performance evaluations. The findings are brought back to members via presentations by the host utility, which are then added to the Transmission Resource Center.

Develop Guidance on Radial Conductor Temperatures and Ratings: Due to the fundamental properties of heat transfer, transmission conductors are hotter at the core than the outer surface. The increased core heat can lead to line sag being greater than projected in software tools. Following the plans shown in the 2025 report, lab testing and modeling will be performed during 2026.

Evaluate Weather Models and Forecasted Ratings: While historic weather data is readily available in many areas, what the forecasted weather conditions were is often not stored or available due to the extreme volumn of data to be managed. In 2026, the ratings team will gather forecasts looking forward for several weather models in multiple locations that can be verified against measurements in the field. This data can be used to help inform the uncertainty of short-term ambient adjusted rating (AAR) and DLR forecasting in future analysis once a statistically significant amount is collected.

Develop Guidance for Accurate LiDAR Measurement Technique: Errors in LiDAR data and line clearance models can contibute to false positives and false negatives when defining the need to upgrade the transmission system. Two recent reports have documented best practices for LiDAR data collection and understanding what options are available to mitigate clearance contraints based on cost and effectiveness. Ongoing study is underway to collect additional LiDAR data which can be validated by physical measurements, which will include performing LiDAR and photogammetry data collection at the EPRI Lenox, Massachusetts, lab using a range of technologies for data capture and analysis.

Document Utility Experience of Adoption of New Regulatory Requirements and Industry Standards: Utilities are required to adjust to ever-changing regulatory requirements and industry standards. This task seeks to provide workflows and best practices to help utilities navigate these changes efficiently and to capture the potential risk exposure of different adoption strategies. During 2026, this task will track utility experiences with adoption of FERC Order 881 in the United States and continue to catalog changes to exising capacity standards and regulations. Interim findings may be discussed at Task Force or similar meetings.

Provide Tools and Resources on the Transmission Resource Center: The following calculators, tools, result summaries, and references are planned to be available on the Line Ratings and Increased Power Flow Transmission Resource Center

Evaluate the Effect of Emissivity on Conductor-Connector Thermal Performance: This task intends to undertake research to understand the thermal effects of having a high-emissivity surface on conductor-connector systems. In 2025, testing was performed evaluating the thermal performance of high-emissivity coatings. In 2026, testing is aimed at evaluating the durability of high-emissivity coatings placed under various simulated stresses.

Update HTC Matrix Software Tool: The High-Temperature Conductor (HTC) Matrix was developed as a repository for all the high-temperature overhead conductor research conducted by EPRI. The HTC Matrix includes several calculators. For 2026, the intent is to update the software for improved usability and accessibility as well as transfer another calculator to the web-based platform. Additionally, a training video of how to utilize the tools will be produced.

Update Guide for High-Temperature Operation with Copper Annealing Predictive Model: This task intends to update the guide developed to assist utilities in safely operating lines at higher temperatures. Each year, a new chapter could be added or an existing chapter updated. In recent years, EPRI has been testing the effects of time and temperature on the mechanical strength of copper conductor strands. In 2026, EPRI plans to analyze results obtained from these copper annealing studies to provide predictive models. This work will be summarized in the guide.

Understand Corrosion at Elevated Temperatures: Corrosion rates increase at elevated temperatures; however, those rates have not been quantified. This task sets out to understand the increase in corrosion rate with elevated temperature. In 2026, the plan is to continue work on the development of equations to model corrosion rates at elevated temperatures.

High-Temperature Effects on Traditional Conductor-Connector Systems: This task sets out to understand the degradation mechanisms of conventional conductor-connector systems, such as copper, all-aluminum conductor (AAC), all-aluminum alloy conductor (AAAC), aluminum conductor alloy reinforced (ACAR), and aluminum conductor steel-reinforced (ACSR). In 2026, the project aims to initiate empirical evaluations of the effects of time and temperature on aluminum alloy conductor strands.

Evaluate Radial Conductor Temperatures and Ratings: Due to the fundamental properties of heat transfer, transmission conductors are hotter at the core than the outer surface. The increased core heat can lead to line sag being greater than projected in software tools. A combination of literature review, modeling, and lab testing can be used to establish correction factors to prevent utilities from exceeding clearance requirements or identifying the required ampacity derates if no action is taken. In 2026, additional emperical studies are planned to further refine predicitive equations.

Develop Guidance on Magnetic Attraction: Increased current loads lead to higher potiential for magnetic attraction. In 2025, EPRI intiated emperical testing to determine the effects of tension, conductor geometry, and current on magnetic attraction in hopes of developing a predictive model to provide guidance on spacer placement. In 2026, EPRI intends on continuing this testing and analysis.

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

Update Guidelines for the Installation of Advanced Conductors: Generally, composite core conductors have different handling and installation requirements compared to traditional steel core conductors. Typical line installation crews are not as familiar with advanced conductor installation requirements compared with the traditional conductors. Most of the premature advanced conductor failures have occurred due improper installation practices. This task intends to compile best practice guidelines based on manufacturer recommendations and utility experience.

Update Guidance for the Inspection of Advanced Conductors: Composite core conductors generally are more fragile than traditional conductors. There may be a need to evaluate the condition of conductors after installation, impact events, or extreme weather. Additionally, as many lines utilizing advanced conductors start to age, there is a need to inspect and assess the core condition. In 2026, this task intends to further refine the inspection technologies previously identified as well as evaluate the feasibility of robotic/crawler line inspection device.

Perform Qualification Testing of Carbon Core Conductors: Because carbon core advanced conductors have only recently been developed, there is a lack of information on how utilities can qualify them for application on their transmission systems. In 2026, this task intends to test and document the results of a new carbon core conductor (e.g. Epsilon Cable HVCRC or De Angeli-Prodotti ACCM, etc.). This information can be used by utilities to properly evaluate advanced conductors.

Identify Best Practices for the Maintenance of Advanced Conductors: Advanced conductors can operate at temperatures more than 150°C. These temperatures could pose a risk for utility workers and the tools that they use. This task intends to evaluate the effects of high temperature on workers and the tools they use, as well as investigate the effects of these tools on the conductors.

Evaluate Environmental Effects’ Impact on the Performance of Advanced Conductors: This task intends to investigate how exposure to various environmental factors might affect the electrical and mechanical performance of HTLS conductors—specifically, non-steel-core HTLS conductors. The factors that intend to be evaluated are fire, tree falls, hurricanes, tornadoes, and others. In 2026, this task is intended to build on the initial fire testing conducted in 2025.

Develop Guide to Safe Design Tension for ACSS Conductor: Determining a safe conductor tension is a multi-faceted problem that requires understanding of the self-damping performance and fretting fatigue endurance of a conductor. This initiative, which is a collaborative effort with project 35.007, is focused on helping solve this problem initially for ACSS conductor, as its self-damping and fatigue properties vary significantly from ACSR conductor.

Evaluate Field-Aged Conductors and Connectors: This task intends to provide an update on the results of evaluations performed on aged HTLS conductors. Through this evaluation, it is envisioned that a better understanding of the aging impact on the electrical and mechanical performance of these conductors may be obtained. In 2026, this document is intended to be updated with the addition of two further advanced conductor evaluations.

Develop Guidelines for the Specification, Selection, and Application of Advanced Conductors: This task develops a guide (which is intended to be updated each year) to assist utilities in the proper selection and application of advanced conductors. The following information intends to be included:

• Field and test experiences with different advanced conductors
• Application case studies
• Documentation and characterization of various types of conductors
• Review and development of technical specifications of the different advanced conductor types
• Review of the various standards associated with advanced conductors

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

Test Quick Break Whip Devices: This task intends to develop guidelines and determine, through laboratory testing, the performance and current handling of quick break whip arc interrupting devices. Since there is currently no test methodology for evaluating quick break whips, this research is intended to advance the knowledge and understanding of laboratory evaluation of these devices. In 2026, EPRI intends to continue to work on electrical and endurance testing, and on developing a free-air arc model.

Develop Inspection and Maintenance Considerations for Line Switches: This task investigates the use and application of existing, new, and emerging technologies for inspecting, assessing, and monitoring the health conditions of line switches. The information obtained is intended to be compiled into a comprehensive guide to form the basis for understanding components, inspection, and monitoring techniques. Technologies such as unmanned aerial systems, testers, and sensors are intended to be explored. In 2026, EPRI intends to work on additional detailed inspection procedures for specific components, such as motor operators, and to include new line switch models in the electronic form for inspection of line switches.

Develop Transmission Line Switch Vintage Guide: This task aims to develop a comprehensive technical resource intended to provide guidance and strategies on procedures to assess the condition of transmission line switches in service by model and vintage. For that, underlying failure and degradation modes and mechanisms have been identified and catalogued by component to help estimat life expectancy and required maintenance actions. In addition, this task assists utilities in the performance of root cause and failure analyses. In 2026, EPRI aims to include results of additional forensic investigations and compile case studies provided by utilities.

Catalog Component Degradation Modes: This task seeks to catalog degradation modes of line switch components from different manufacturers. Every year EPRI updates the Transmission Resource Center (TRC) with new findings from forensic investigations performed in previous years and utility reports.

Update Practical Installation Guide of Line Switches: This is a living task intended to provide the technical basis and guidelines to support and help in-the-field engineers and technical staff with information regarding component specification, design, installation, and commissioning protocols of new equipment, as learned through best practices. In 2026, EPRI intends to continue working on a compilation of utility line switch installation design templates.

Evaluate Motorized Switches: This task seeks to gain a better understanding of the functionality of and the inspection techniques required for motorized switches compared to manually operated switches. Possible topics include the additional components needed for motorization, such as batteries, SCADA, and alternatives of power supply. Findings from this task are shared through the Inspection and Maintenance Guide and the Line Switch Vintage Guide Technical Update.

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

Update HVDC Electrical Effects Module in TLWorkstation: Based on the results and data obtained from the reduced-scale, full-scale, and operational line measurements, the existing algorithms used in the EPRI TLWorkstation software tool intend to be updated and the user interface improved.

Update HVDC Transmission Line Reference Information: This task intends to update the Overhead Line specific HVDC reference document which was previously published by EPRI in the early 1990s. This document details the design characteristics of existing lines, and describes the testing conducted and results obtained in determining the corona and electric field characteristics of HVDC transmission lines.

Update HVDC Line Design Guide: This task, updated each year, collects relevant information on HVDC line designs from various completed HVDC research tasks. Topics will include design aspects pertinent to HVDC and will identify areas of design that are similar between dc and ac. The guide is updated each year with new information.

Perform Live-Line Tool Testing: This task intends to test live-line tools under HVDC conditions. The plan is to investigate the effects of space charge and corona to determine their impact on the flashover performance and voltage distribution along the length of the tool. Work might also be done to determine the accuracy of voltage detection devices under HVDC conditions.

Evaluate Insulator Dimensioning for Contaminated Environments: Contamination is the main driver for insulation coordination of HVDC lines. Contamination performance of DC is vastly different from AC. This task intends to determine the latest state of the science in HVDC insulator dimensioning for contaminated environments. Testing and long-term aging of insulator materials may also be carried out.

Update HVDC Reference Book (The Olive Book): An electronic version of the updated HVDC reference book will be made available to project funders. This reference book, updated each year, contains information on overhead lines and converter stations.

Perform Hardware and Insulator Corona Tests: When specifying corona requirements for HVDC insulator hardware assemblies, many utilities use the equivalent peak ac voltage for testing. Currently, no HVDC hardware corona test specifications exist. This task intends to develop test specifications based on laboratory testing and develop guidelines to assist in specifying corona tests for HVDC hardware. In 2026, the intent is to review numerical simulations and to update the testing protocols.

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