Electricity cut out around 9.45am affecting shops and businesses in the centre of town and the nearby industrial area.
While power has been restored to some areas other customers are reporting they are still without electricity.
PowerNet said the outage occurred after a power pole went down near the recycling centre at about 9.30am.
This impacted customers in the CBD as well as further afield, including Otatara.
While PowerNet was able to restore power to the area around 10.15am, a further fault had occurred.
"We are working to investigate the cause and restore power to all affected customers."
Invercargill City Council said the city's library was closed because of the outage.
It was hoped power would be fully restored by 1pm.
Shops on Esk St resorted to cash transactions with eftpos not operating.
