Firefighters spent about an hour at the Palm Beach Boulevard property putting the fire out.
The bathroom was gutted.
Eastern Bay of Plenty fire safety officer John Rewi was called in to determine the cause of the fire. "The fire started from a three-in-one heat lamp, fan and light. It's just one of those things that happens," he said. "It is something that does happen, in particular the heat lamps coming on without the fan. They get hot and cause a fire."
The light melted the fitting and it fell down on to the clothes rack, setting the garments on fire.
If the fan had been on as well it would probably have cooled the lamp and prevented the fire, Mr Rewi said.
Heat lamps were often wired so the fan automatically came on when the heat lamp was turned on, he said.
Ms Adams said it was a warning to others to make sure the fan was on if using the heat lamp.