The wooden pole is believed to have rotted through, causing it to fall on to private property about 2am, damaging a car.
Delta chief executive Grady Cameron said the incident was regretted and Delta had been in contact with the property owner about damage caused, and the company's insurers in regard to compensation.
''We are currently investigating the sequence of events that led to the pole's failure. What is clear is that the pole had internal rot that was not easily detectable.''
Mr Cameron said the pole had been replaced with a new hardwood pole.The condition of all poles on the Aurora Energy network were checked regularly as part of scheduled maintenance and the pole in question was last checked in 2011.
''However, it is not always possible to accurately assess the internal condition of wooden poles.
''We have an extensive and ongoing pole replacement programme on the Aurora Energy networks in Dunedin and Central Otago,'' he said.