Explosions 'like a cannon going off” rocked a Mount Maunganui industrial suburb last night when a brand new transformer caught fire.

The incident happened at Bakels Edible Oils on Hutton Place at around 8:40pm.

A brand new transformer shorted and blew up on Hutton Place last night.

Firefighters had to stand and watch the exploding arcing transformer fire for about 20 minutes before it could be isolated from the power supply, says Mount Maunganui fire service station officer Roger Pickett.

'That's the thing with those things,” says Roger. 'You can't do anything with them other than keep people away from them and make sure it doesn't set fire to anything else.

'We had to wait for Powerco to get there. That took 20 minutes or so, and once they got there they had to go back further along the transmission line to isolate it.

'Once they had done that the fire was out in three or four minutes.

'We can't start putting stuff on those things while it's still live. You would have fried firemen then.

'We had a covering delivery in case it really burst into flames and threatened the building. We could put a water curtain down there, but we didn't have to do that.

'It was really confined to the transformer itself. It burned out one end of the unit so Bakels had to basically close down for the night because they didn't have any power.”

The industrial strength 750kv transformer was brand new and fire fighters were told it wasn't drawing anywhere near its capacity. Powerco told fire fighters the cause was an unspecified short circuit.

Bakels Edible Oils reported today they were back in operation by 1am, running on a generator, which is expected to keep the plant running for the next day or so until the mains power is restored.