Updates & Events
Info for members about events, updates, and results
In 2026 we are planning to undertake several tasks in P35.007, Line Design, including those listed below:
- 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, 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 ACSS conductor, as its self-damping and fatigue properties vary significantly from ACSR conductor. In 2026, EPRI intends to continue their 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 765kV expansion has placed emphasis on steel lattice tower design, which is a support options 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 cover 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 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.
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 |
| Orange Book Training Course: Ch 3 - Fatigue of Overhead Conductors (35.007) | March 25 1:30-3:00 pm ET | Webcast | David Folk Pierre Marais |
More information coming soon |
| Transmission & Substations Advisory Meeting | March 30 - April 1 | Charlotte, NC EPRI Offices | Rachel Moore | Meeting Information |
| Information Exchange Session: Identification and Resolution of Post-Construction Clearance Violations (P35.007) | April 16 10:00- 11:30 am ET | Webcast | David Folk Pierre Marais |
More information coming soon |
| Lattice Tower Design Course (P35.007) | May 12 (TIME) | Charlotte, NC | David Folk Pierre Marais |
More information coming soon |
| EPRI R&D Project Update Webcast: Composite Structures, Line Design, Increasing Line Resiliency (P35.005, P35.007, P35.008) | June 3 2:00-3:00 pm ET | Webcast | David Folk Pierre Marais |
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: Composite Structures, Line Design, Increasing Line Resiliency (P35.005, P35.007, P35.008) | November 18 2:00-3:00 pm ET | Webcast | David Folk Pierre Marais |
More information coming soon |
2026 Anticipated Deliverables
| Product Name | Deliverable type |
|---|---|
| EPRI AC Transmission Line Reference Book - 200 kV and Above (The Red Book) | Technical Update |
| EPRI Red Book Application Suite | Software |
| EPRI Transmission Line Reference Book: Conductor and Structure Motion (The Orange Book) | Technical Update |
| EPRI Transmission Line Reference Book: 115– 400 kV Compact Line Design (The Blue Book) | Technical Update |
| Quantifying the Real Cost of Pole Material Options : 2026 Edition | Technical Update |
| Best Practices for LiDAR data in Overhead Line Design Software | Technical Update |
| Safe Design Tension of ACSS Conductor: 2026 Edition | Technical Update |
| Orange Book Seminar 2 - Fatigue of Overhead Line Conductors | Training Workshop |
| Training Workshop : Lattice Design | Training Workshop |
| NESC Clearances Calculator V1.0 (Beta) | Pre-Software |
| NESC Clearances Calculator V1.0 (Production) | Software |
| Optimal Line Tension Calculator Op10 v2.7 (Beta) | Pre-Software |
| Optimal Line Tension Calculator Op10 v2.7 (Beta) | Software |
| Transmission Line Workstation Gen 2: Design Modules Vibration (TLW-Gen2) v14.0 (Beta) | Pre-Software |
| Transmission Line Workstation Gen 2: Design Modules Vibration (TLW-Gen2) v14.0 | Software |
2025 Engagement Opportunities
| Meeting | Date | Location | Information |
|---|---|---|---|
| Overhead Line Design 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 |
| Online Training for Orange Book | April 24 2:00-3:30 pm ET |
Webcast | Meeting Materials |
| EPRI R&D Project Update Webcast: Composite Structures, Line Design, Increasing Line Resiliency (P35.005, P35.007, P35.008) | May 29 2:00 - 3:00 pm ET |
Webcast | Meeting Materials |
| Training: Calculation of Overhead Line Loads- Session 1 | June 4 2:00-3:00 pm ET |
Webcast | Meeting Materials |
| Training: Calculation of Overhead Line Loads- Session 2 | July 9 2:00-3:00 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 |
| Overhead Line Design Task Force | August 18-22 (In-person) August 25-29 (Virtual) |
Charlotte, NC | Meeting Materials |
| Red Book Training | September 29-October 2 8:00-4:30 pm ET |
Charlotte, NC | jcardoso@epir.com |
| EPRI End of Year Webcast: Composite Structures, Line Design, Increasing Line Resiliency (P35.005, P35.007, P35.008) | November 13 2:00-3:00 pm ET |
Webcast | Meeting Materials |
2025 Deliverables
In 2025, a mix of ongoing research initiatives together with new research areas will be undertaken.
| Product ID# | Deliverable | Type | Date |
|---|---|---|---|
| 3002032759 | EPRI AC Transmission Line Reference Book: 200 kV and Above: 2025 Edition | Reference Book | December 2025 |
| 3002033679 | Red Book Application Suite v2.5.1 | Software | December 2025 |
| 3002033832 | Red Book Web Apps | Software | December 2025 |
| 3002032758 | EPRI Transmission Line Reference Book: Conductor and Structure Motion: 2025 Edition | Technical Update | December 2025 |
| 3002032762 | EPRI Transmission Line Reference Book: Compact Line Design (Blue Book)-2025 Edition | Technical Update | December 2025 |
| 3002032743 | Transmission Pole Material Selection Guide : 2025 Edition | Technical Update | December 2025 |
| 3002032764 | OHL Line Design guide - Considerations for Extra - High Voltage Design | Technical Update | December 2025 |
| 3002032765 | Safe Design Tension of ACSS Conductor: 2025 Edition | Technical Update | December 2025 |
| 3002032052 | Orange Book Seminar 1 - Orange Book Overview & Single Conductor Aeolian Vibration | Technical Update | December 2025 |
| 3002032581 | Training Workshop : Calculation of Overhead Line Loads- Session 1 | Workshop | December 2025 |
| 3002033219 | Training Workshop : Calculation of Overhead Line Loads- Session 2 | Workshop | December 2025 |
| 3002033829 | Transmission Line Workstation Gen 2: Design Modules Vibration (TLW-Gen2) v13.0 | Software | December 2025 |
| 3002033298 | Optimal Line Tension Calculator Op10 v2.6 | Software | December 2025 |