UK Power Networks were made aware of the issue affecting homes in the Attleborough area after several reports at 9.40am.
308 customers and four postcode areas have currently been affected.
Engineers are now on site, carrying out investigations into the fault.
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Once they have completed their assessment, they will carry out repairs with the hope of restoring power to homes and businesses.
The company has estimated that the power will be back on between 11am and midday today.
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However, this timeframe may change and be extended depending on investigations and the work involved to resolve the issue.
The cause of the power cut is believed to be due to a high voltage overhead electricity line.
More updates to follow.