Project 35.002 – Conductor, Shield Wire, and Hardware Corrosion
Objective
Corrosion of conductors, shield wire, and in-line hardware affects the mechanical strength of those materials potentially leading to fracture and the dropping of phase or ground lines. To ensure the reliability and safety of overhead transmission lines, it is critical to understand why and how conductors, shield wires, and line hardware corrode.
The objectives of this project are to increase understanding of:
- How conductors, shield wires, and hardware corrode
- How to optimize inspection of conductor, shield wire, and hardware
- The efficacy of corrosion-inhibition methods
- How to determine the anticipated service life of these components in various corrosive environments Asset managers can then use this knowledge to select components best suited to their specific environmental conditions, set timelines for inspection, and prescribe mitigation or remediation actions.
Research Value
Research on corrosion of conductor, shield wire, and line hardware is intended to improve safety, reliability, and efficiency of the overhead transmission system for member utilities and the public by:
- Improving the selection of materials based on the environmental conditions
- Providing effective corrosion mitigation strategies based on the materials and environmental conditions
- Providing anticipated degradation rates to assist in determining effective inspection and remediation prioritization
Approach
This project addresses the issues surrounding corrosion of conductors, shield wires, and hardware by providing members with the tools and references to make the most informed and cost-effective management decisions regarding the asset’s maintenance, inspection, and selection. EPRI aims to achieve the objectives of this project by performing the following tasks:
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:
| Resource Title | Resource Type |
|---|---|
| ACSR and ACSS End-of-LifeCalculator | Calculator |
| Corrosion ManagementReference Book (The Rust Book) | Reference |
| Corrosion Failure of a Conductor Located Near anIndustrial Site | Results Summary |
| AAAC Flint Forensic Report | Results Summary |
| Geometry Factor Development | Results Summary |
| Condition Assessment Comparison of Two CoastalAluminum Conductors | Results Summary |
| Corrosion Monitoring System | Results Summary |
| Laboratory Corrosion Resistance Evaluation ofConductor Strands | Results Summary |
| Forensic Analysis of Hardware Due to Corrosion Damage | Video Highlight |
Anticipated Deliverables
| Deliverable | Deliverable Type |
|---|---|
| ACSR and ACSS End-of-LifeCalculator | Web-Based Tool |
| Aluminum Corrosion inOverhead Lines Conductors | Technical Update Report |
| Conductor Corrosion ConditionAssessment | Technical Update Report |
| Evaluation of Shield WireCorrosion | Technical Update Report |
| Design for ExtremeEnvironments Workshop | Workshop |
| Corrosion ManagementReference Book (The Rust Book) | Reference Book |
Past EPRI Work on Topic
| Product ID | Title | Description | Published Date |
|---|---|---|---|
| 3002029559 | Atmospheric Corrosivity Mapsfor Conductor Modeling: Selection and Application of Conductors for SevereService Environments | This report provides guidanceon how to build an atmospheric corrosion map, which can be used by utilitiesto align their inspection and replacement schedule with actual corrosiondegradation measurements. | December 2024 |
| 3002021805 | Corrosion ManagementReference Book | This technical report providesinformation to better understand methods to locate, inspect, assess, andmitigate corrosion. | December 2022 |
| 3002026928 | Conductor Selection andApplication for Corrosive Areas | This report highlights thefactors governing ACSR and ACSS corrosion. Utilities can use these findingsto better selection conductors that will withstand severe corrosion areas. | December 2023 |
| 3002021462 | Understanding Conductor andHardware Corrosion due to Vibration: Fretting Fatigue and Wear | Fretting corrosion has beenidentified as a mechanism that accelerates the degradation of the galvanizedsteel core of ACSR and ACSS conductors. | December 2021 |