UI Energizes New Pequonnock Substation to Improve Electricity Reliability and Resiliency for Bridgeport Customers

$142 million infrastructure investment demonstrates UI’s commitment to strengthening distribution, transmission network in wake of more severe storms, flooding incidences


Video linked HERE. Photos and B-Roll linked HERE.


BRIDGEPORT, Conn. — March 22, 2024 — United Illuminating (UI), a subsidiary of Avangrid, Inc. (NYSE: AGR), announced the energization of the new Pequonnock Substation that will now provide safe, reliable power to UI distribution customers in the greater Bridgeport area and millions of New Englanders served by the Independent System Operator of New England (ISO-NE) transmission system. The new substation, which is a rebuild of Old Pequonnock Substation, has been moved 700 feet southwest of its former location, away from the Pequonnock River, and set five feet above the 100-year flood level. The $142 million infrastructure investment was designed to mitigate coastal flooding and implement upgrades to the bulk electric system to ensure uninterrupted electricity service to residents and businesses in Bridgeport, Fairfield, and across the ISO-NE service territory.

“We’re pleased to reach this new milestone in the rebuild of Pequonnock substation, which ensures all our customers, particularly our urban centers and Environmental Justice communities, have access to safe and reliable power,” said Frank Reynolds, President and CEO of United Illuminating. “As the demand for and reliance on electricity continues to increase, ensuring our critical infrastructure like Pequonnock Substation is protected from coastal flooding and other weather-related threats is becoming even more imperative. This substation rebuild is the latest demonstration of our company’s commitment to meeting increased electricity demand as we look forward to a sustainable future.”

United Illuminating energized Old Pequonnock substation in 1956. The substation is located on the banks of the Pequonnock River at the mouth of the Long Island Sound. During Hurricane Irene (2011) and Superstorm Sandy (2012), significant storm surge threatened to cause a long-lasting catastrophic outage for both transmission and distribution customers. As a result, UI proactively de-energized Pequonnock Substation, which preserved the transmission system but resulted in outages for approximately 40,000 customers in the greater Bridgeport region.

“The newly built Pequonnock substation is a key component in our local and regional electric system, and I’m proud to see our team's efforts and vision become a reality today,” said Jim Cole, Vice President of Projects at Avangrid. “The substation runs on the industry's most innovative, cutting-edge technology and state-of-the-art design. I’m proud to say that this new substation is built to last and will be able to withstand the effects of rising sea levels and increased demand on the electric grid.”

Substations are considered energized plants-in-service as soon as the first cutover is complete. Last week, New Pequonnock reached this milestone with the initial energization of the 115 kV high-voltage gas-insulated switchgear (HVGIS) as well as the energization of the 115/13.8 kV station transformers. Over the next 10 months, the UI team will begin transferring seven transmission lines and all distribution circuits to the new substation, with the first transmission line cutover beginning late last week. The substation is expected to be fully commissioned in the first quarter of 2025.

Additional details on the project can be found on the Connecticut Siting Council’s website at: ct.gov/csc/DocketNo.483 

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