A Fire and Emergency New Zealand (Fenz) spokesman said crews from Alexandra, Clyde and Cromwell arrived on the scene about 1.50pm yesterday after "smoke was seen" from a building in Clyde Dam's powerhouse.
Four appliances, a support vehicle, a command unit and a fire investigator attended and remained on site for about 90 minutes before handing the scene to dam staff.
Contact Energy head of hydro-generation Boyd Brinsdon said no-one was injured in the incident.
"All our people and contractors — following an audible explosive noise in the powerhouse — are safe and accounted for."
He said the incident occurred during the restart of a generator unit, which had been out of service for a several weeks.
"We were just going through a recommissioning phase and had started the generator.
"At this point it looks like a localised failure of a very auxiliary piece of electrical equipment."
The damage appeared to be limited and would affect a single generator at the Clyde Dam, Mr Brinsdon said.
"[It is] inconsequential compared to the safety of our staff."
All staff were evacuated from the dam in under two minutes, Mr Brinsdon said.
The incident would have no impact on the dam’s ability to manage water coming downstream from rain events, he said.
"None of that there is a problem for us and today’s incident with the fire brigade doesn’t change anything in that regard.
"We’ll just be generating with three units instead of four."
Mr Brinsdon stressed the incident was unrelated to four sticks of the explosive PowerGel which were recently found downstream of the dam.
