A power cut knocked out electricity to almost 2,400 homes and businesses.
It happened at 10.21am on Tuesday, when UK Power Networks was made aware of the issue.
The utility firm said it believes a fault on its overhead network is behind the problem which is affecting properties in Thorpe Hamlet, on the outskirts of Norwich.
Initially, 2,382 homes and businesses were left without electricity, though engineers have been able to reroute power to some remotely.
As of 10.45am, 622 of its customers remained without power.
UK Power Networks estimates it will be able to restore supply to all those affected by 1pm.
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