Based in Brighton, CO, United Power Inc. is the 2nd largest electric cooperative in Colorado. With over 5,000 miles of power lines and nearly 83,000 meters, they serve over 200,000 customers along the north central range of the Colorado Rockies. A section of the United Power service area also heads up into the mountains, providing power to some 5,500 remote homes in and around the 12,000 acres of Golden Gate Canyon State Park.
Rugged terrain and challenging access proves difficult for any cooperative or utility to maintain a reliable network. So when it came time for United Power COO Bryant Robbins and his team to look at upgrading sections of a single phase distribution line – which was over 50 years old – they needed a solution that would minimize maintenance and provide them with long-term reliability. But it also needed to address their fire mitigation, wildlife protection, and storm hardening needs.
“With the dense forest coverage in the park, and the winds that are constantly blowing, we have a significant amount of fire potential up in the hills,” says Robbins, COO of United Power. “It’s all about risk management and reliability to our members, so whatever we could do to minimize the risk and minimize that fire potential is what we needed to consider.”

The choice for fire mitigation

Given the mountainous region and difficult access, an underground cable solution was not a viable option that could be considered by the cooperative. Overhead lines were the only way to go, and bare wire was not going to give them the fire mitigation requirement they were looking for. In February of 2016, Robbins and United Power put a commercial agreement in place with Hendrix Wire and Cable, to use the Hendrix Aerial Spacer Cable Systems (ACS) for an initial 2.8 mile single-phase, 7.2 kV circuit. In addition to being reliable, environmentally friendly, and economically sound, Hendrix ACS was proven to be a strong asset for utilities and cooperatives in areas prone to fires. ACS installation and material costs are typically less expensive than underground, ACS eliminates or reduces momentary faults and outages, and it requires less tree management than traditional bare wire over the long term.
The basic structure of ACS is three covered conductors supported by a grounded messenger, all run separately and all held together by interspersed spacers that keep the cables strategically positioned along the length of the span. The supporting messenger provides a barrier and protection from falling trees and limbs. The footprint of a 15kV - 3 phase system is less than 24” in height and 17” in width, greatly reducing the amount of vegetation trimming and frequency. Additionally, if the pole and/or cable does happen to come down, the covered conductor is much less apt to start a fire versus bare wire, which would tend to arc when broken or become compromised in any way.

Read full article in the Critical Power Reliability Special Edition 2021.