Fire and Emergency New Zealand Senior Station Officer Pete Douglas, of St Kilda, said crews were called to reports of smoke in the ceiling of the power room of Torpedo 7, in Andersons Bay Rd, about 9.50am yesterday.
When the manager had smelt something untoward, he had called for firefighters, SSO Douglas said.
Staff did all the right things and it meant the fire was confined to the switchboard.
Staff switched off the power and went with customers across the road, which made the job of firefighters "a whole lot easier", SSO Douglas said.
There had been a few customers in the store, including one who was trying on a wetsuit.
The rest of the store only suffered minor smoke damage, but the fire could have been much worse, he said.