More than 2,000 homes were left without electricity during a power cut that lasted more than four hours.
About 2,200 homes in the north Worthing and Lancing area were affected by the blackout, which happened at 12.45am on Saturday.
The fault was traced to a sub-station in Mendip Road, Worthing.
More than half the homes were reconnected by 1.30am and the rest were hooked up to neighbouring sub-stations over the next three hours.
Nick Akers, from Seeboard, said: "We worked throughout the night to get everyone connected to other substations.
"Our engineers will be working on the faulty substation straight away to get it fixed."
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