A Northland business leader says the large power outage will significantly impact business.  

Widespread power outages began yesterday morning when a transmission tower toppled at Glorit, northwest of Auckland. 

NorthPower says supply has since been restored to the majority of Northland. 

Top Energy is showing 61 customers in Bay of Islands still without but warns there's potential for further outages as they manage load restrictions.  

North Chamber chief executive Darryn Fisher told Mike Hosking that the business impact isn't yet known, but he expects it'll be significant with economic head winds already at play. 

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