Updates & Events
Info for members about events, updates, and results
In 2026 we are planning to undertake several tasks in P35.006, Lightning Performance and Grounding, including those listed below:
- 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.
2026 Engagement Opportunities
| Event Name | Date | Location | Contact | Information |
|---|---|---|---|---|
| Transmission and Substations Task Force Meeting | February 9 - 12 | Charlotte, NC EPRI Offices | Rachel Moore | Meeting Information |
| Transmission & Substations Advisory Meeting | March 30 - April 1 | Charlotte, NC EPRI Offices | Rachel Moore | Meeting Information |
| Grounding for Overhead Transmission Lines Workshop (P35.006) | June 8 | Lenox, MA | Camille Le Mauff | More information coming soon |
| EPRI R & D Project Update Webcast: Lightning and Grounding (P35.006) | June 16 11:00 am - 12:00 pm ET | Webcast | Camille Le Mauff | More information coming soon |
| Overhead Transmission 2025 ARP Rollout #1 | June 18 10:00 - 11:30 am ET | Webcast | Rachel Moore | More information coming soon |
| Overhead Transmission 2025 ARP Rollout #2 | July 30 10:00 - 11:30 am ET | Webcast | Rachel Moore | More information coming soon |
| Transmission and Substations Task Force Meeting | August 10-14 | Charlotte, NC EPRI Offices | Rachel Moore | More information coming soon |
| Transmission & Substations Advisory Meeting | August 31- September 2 | Rachel Moore | More information coming soon | |
| EPRI R & D Project Update Webcast: Lightning and Grounding (P35.006) | December 3 11:00 am - 12:00 pm ET | Webcast | Camille Le Mauff | More information coming soon |
2026 Anticipated Deliverables
| Deliverable | Deliverable Type |
|---|---|
| Using LiDAR Data to Estimate the Shielding Failure Performance of Existing Lines: A First Test | Technical Update Report |
| Electromagnetic Survey Techniques to Estimate the Soil Resistivity: Comparison with Numerical Simulations | Technical Update Report |
| Using Ground-Penetrating Radar to Assess Existing Buried Electrodes | Technical Update Report |
| Lightning Impulse Tests on Brace Post Insulator Configurations | Technical Update Report |
| New version of TLW-Gen2: Lightning Performance and Power Frequency Grounding modules; | Software |
| Lightning Performance and Grounding Reference Book (The Gray Book) | Reference Book |
| In-person Training Workshop on Transmission Line Grounding | Workshop |
2025 Engagement Opportunities
| Meeting | Date | Location | Information |
|---|---|---|---|
| Lightning and Grounding Task Force | March 10-13 (In-person) March 17-20 (Virtual) |
Charlotte, NC | Meeting Materials |
| EPRI Overhead Transmission Program (P35) New Supplemental Launch Webcast | April 3 2:00 pm - 3:00 pm ET |
Webcast | Meeting Materials |
| EPRI R & D Project Update Webcast: Lightning and Grounding (P35.006) | June 17 11:00-12:00 pm ET |
Webcast | Meeting Materials |
| Overhead Transmission 2026 ARP Rollout #1 | July 17 10:00 am - 11:00 pm ET |
Webcast | Meeting Material |
| Overhead Transmission 2026 ARP Rollout #2 | July 24 2:00 pm - 3:30 pm ET |
Webcast | Meeting Material |
| Lightning and Grounding Task Force | August 18-22 (In-person) August 25-29 (Virtual) |
Charlotte, NC | Meeting Materials |
| EPRI End of Year Webcast: Lightning and Grounding (P35.006) | December 4 11:00-12:00 pm ET |
Webcast | Meeting Materials |
2025 Deliverables
| PID | Deliverable Title |
|---|---|
| TRC | Gray Book Applications Web Apps |
| 3002032746 | Transmission Line Workstation Generation 2 (TLW-Gen2) v13.0: Lightning Performance (TFlash) and Power Frequency Grounding Modules |
| 3002032752 | EPRI Transmission Line Reference Book 2025: Lightning Performance and Grounding (Gray Book) |
| 3002032753 | Evaluation of Rizk's Simplified Lightning Attachment Method for Estimating Shielding Failures |
| 3002032754 | Acquisition of a High Daily Volume of Soil Electrical Resistivity Data: Comparison of Electrical and Electromagnetic Methods |
| 3002032755 | Lightning Impulse Strength of Transmission Lines: Impulse Testing of a 138 kV Braced Post Assembly |
| TRC | Surge Arrester Database |
| 3002033914 | Improving the Quality of Ground Resistance Measurements for Transmission Line Structures: Understanding the Fall-of-Potential Method |
| 3002033949 | Selection of Transmission Line Surge Arresters: A Simplified Method for Lines with Overhead Ground Wires |
| TRC | Ground Flash Density Map for Continental US |
| TRC | Drawing Measurement Tool for Dry Arc Distance Measurement |