CONNECTICUT — United Illuminating has filed for a rate increase with the Public Utilities Regulatory Authority. If approved, the hike would take effect May 1, 2024, and average around 12.3 percent, or $30 for residential customers.

The move Friday came just a day after Eversource filed its ask for a $38, or 19 percent, increase.

The two power companies largely attribute their request of the regulators to a 2019 state deal cut with Dominion Energy, which operates the Millstone nuclear power station in Waterford. The arrangement locked in a minimum rate for Dominion over the next decade. The Dominion facility is the state’s largest source of clean power.

State initiatives adopted during the COVID pandemic to shield low income and medical hardship customers from high energy bills are also bearing blame for the rate increases. “Overdue customer balances are paid for by all customers,” Eversource officials said in a news release Friday.

UI is the smaller-by-far of the two utilities, serving customers in 17 communities, including Milford, New Haven and Bridgeport.

“While the cost increases are outside UI’s control, we understand their impact on our customers,” said Sarah Wall Fliotsos, a spokeswoman for the Avangrid subsidiary.