A deactivated 11kV Aurora Energy line the company’s staff were working on came into contact with a nearby live 33kV Talla Burn line.
WorkSafe confirmed yesterday the investigation would be carried out by Connetics through the "duty holder review process".
The voluntary process is designed to ensure the company understands the cause of the event and how improvements can be made.
The process is not intended to apportion blame.
Connetics was appointed by Aurora Energy in August 2018 to carry out maintenance, renewal and development work on its network in Central Otago.
A spokeswoman for Connetics said no-one was harmed in the incident.
"An investigation is under way and our people are fully co-operating.
"All learnings from this investigation and any resulting actions implemented will be shared with appropriate stakeholders."
"Connetics has engaged an independent contractor to carry out an investigation into an incident at Millers Flat. The person is based outside our Southern Region and is an experienced health and safety investigator. As the investigation is underway we will not be making any further comment."
