The fire at Rotorua's St John's Church was not deliberately lit but was caused by the failure of a set of fluorescent lights, an investigation has found.
Fire Service Central-Lakes region assistant area commander Hamish Smith and fire risk management officer Stuart Bootten told the Rotorua Daily Post this afternoon they had ruled out arson and the fire was not in any way suspicious.
The church, on the corner of Ranolf and Victoria Sts, was gutted by fire last Wednesday, with police saying they believed the fire was suspicious. They appealed for anyone who saw a person or people near the church before the fire or running away from it soon after.
But Mr Bootten said the fire started inside a set of fluorescent lights above the altar in the main part of the building and spread rapidly.
"We had lots of information come in from the public ... but the fire investigation has eliminated any fire starting from the outside of the building.
"We have found that in the main altar area within the main auditorium the fire has spread across the roof and through the roof voids to other areas of the church, making it very difficult to contain.
"It has been a high fire, meaning it's up at ceiling level and in the roof area."
He said the fire was first spotted by a security guard reacting to a monitored security and fire alarm system, but could have been better contained if the church had a sprinkler system.
"There was no fire visible outside the building when the security guard arrived."
Mr Smith said the guard broke into the church to try to put the fire out.
"But he only got two paces into the building before the fire became too intense.
"From that point the fire's development was rapid, high and very hot," Mr Smith said.
Mr Bootten warned owners of older fluorescent lighting systems to have them checked or replaced as this was the third major fire in the past five years linked to older-model lighting systems.
The minister of St John's Presbyterian Church, the Reverend Ed Masters, said while parish members were devastated at the loss of the church, they were relieved it was not caused by arson.
"It would have been so sad if someone had made a mistake that interrupted their life in such a significant way," he said.
"We believe our city is full of wonderful young people and are so pleased that none of them are implicated in the cause of this tragedy."