As the fire started raged along the Port Hills yesterday, soot affected the high voltage lines and caused the circuits to trip at the Bromley substation in Christchurch.
The local lines company Orion says that knocked out power to 39,000 customers.
Late yesterday, flames could be seen near Transpower's pylons and lines.
But the national grid operator says it won't be able to inspect them until it is safe to do so.
Transpower's General Manager Mark Ryall spoke to Ingrid Hipkiss.
