Power has been restored to more than 10,000 people in Hamilton and the surrounding areas.
A Powercor spokeswoman said crews were able to restore power to all customers by 1.20pm.
She said the cause was being investigated.
More than 10,000 people in Hamilton and surrounding areas are without power.
A Powercor spokeswoman said crews were working to restore power to about 13,000 customers.
"Power was impacted about 12.30pm," she said.
"At this stage, the estimated time of restoration is 3pm but we expect to get power back on before then."
The spokeswoman said customers were being updated via SMS, Powercor's website and its call centre.
"We thank customers for their patience as our crews work to get power safely restored as quickly as possible," she said.
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