Reduce Outages by Designing Better Structures

Lab testing is a critical step to improve resiliency

One of the best ways to understand how a structure performs is to see it in action. Normally, this would require you to be in the field when a tree or branch falls on a line. EPRI’s laboratories are able to perform this test safely, repeatably, and with full data and imagery collection.

The purpose-built test site at EPRI’s High Voltage laboratory in Lenox, Massachusetts gives utility designers and engineers the ability to see their designs in action and identify opportunities to improve the design in real-time. The researchers construct full-scale structures built to your specifications, then subject the structure to the impact of a mid-span tree-strike or falling branches. Sensors and cameras capture the action so that the test team can analyze performance and identify design changes that could improve performance.

Major weather events necessitate improved resiliency and reduced restoration time. EPRI collected data to identify time consuming restoration tasks. Replacing broken poles was, by far, the most time-consuming task

Design characteristics to improve through testing

EPRI can test multiple characteristics of designs and components. Two of the main objectives of the testing are to reduce restoration time by pole saving and increasing reliability through branch deflection.

Pole Saving

EPRI’s resiliency research results have shown that a key to reducing restoration time is predictable and consistent structure performance during storms. Put simply, it is important to know the order in which components will fail, and it is important that the pole itself is not the first component on that list.

One approach is to apply the concept of mechanical coordination to your designs. Coordination is well understood in power system protection, and the same concept can apply in structure performance. Unlike protection system coordination, however, structures are made up of physical components with unknown or unpredictable performance characteristics. This makes it very difficult to model or simulate structural performance.

EPRI’s resiliency research results have shown predictable and consistent structure performance is key to reducing restoration time after storms. Put simply, it is important to know the order in which components will fail and that the pole itself is not the first component on that list.

The Test Site

Explore the test site by hovering over the green highlighted areas.


How it works

Watch a virtual tour of the test site with EPRI Project Manager Joe Potvin below.

The EPRI test site is designed with the flexibility to meet your needs. We have tested many types and sizes of structures. Call us to talk about how we test your structure!

Utilities use the full-scale test facility to assess potential resilient design improvements. The failure mode of this structure was typically a broken pole. Testing demonstrated the need for an improved design.

Branch Deflecting

Fallen tree branches cause many outages, often by getting stuck on the line and creating an electrical fault. This test helps identify conductor configurations that are less likely to cause reliability issues when branches fall on them. Testing includes multiple combinations os configurations, as well as branch species and types that are representative of your utility’s service territory.What if we could identify conductor configurations that branches are less likely to get caught on?

EPRI can simulate fallen branches on overhead lines by literally dropping branches from above. However, this requires careful consideration of representative tree species, review of outage data, and discussions with utility vegetation experts.


Branch deflection vs capture depends on many factors, including branch shape, line configuration, and how the branch contacts the line. The results rely on many individual tests to generate statistics.


Results can also demonstrate branch species that may be more problematic and require more management.

How to get involved

If you would like to schedule testing of your designs, please contact our research leader, Joe Potvin, at

Find more information here.