The fire was out when the fire brigade arrived and the crews spent about two hours cleaning up the flood caused by the sprinklers.
Mr Sabin said it was not until the crews were investigating what set alarms off that they realised there had been a fire.
"Nobody on site was aware there had been a fire as the top floor was unoccupied.
"We don't know what actually caused the fire but it definitely originated in some telecommunications equipment.
The fire damage was limited to the room and there was some superficial smoke damage. There was about 150 sq m of water damage."
Mr Sabin said it was pleasing to see a working sprinkler system, but it was a shame the fire alarm was so far from the origins of the fire as the crews could have arrived sooner.