Five-year-old Todd Sutherland ran straight to his mother Maree Turnbull to tell her the plastic stand underneath a glass globe was on fire after sunlight through the globe sparked a flame.
The room was lit directly by afternoon spring sun through a window.
"He said, '... there's smoke, and there's even a flame, Mummy,' and I basically ran in one movement, blew it out and threw it out the door."
No-one was hurt in the tiny fire last week but it could easily have been much worse, Ms Turnbull said.
The globe was sitting on a window sill about 25cm from her 3-year-old daughter Maddison's head and only centimetres from a curtain around which Todd and his friend were playing when the globe's stand started smoking.
When the Otago Daily Times visited the family's Wakari home with a fire safety officer, the globe's base started smoking in the spot where the magnified sunlight hit it less than two seconds after it was placed on the sunny window sill.
"What if we'd been out, in another room or away for the weekend, or my daughter was having her afternoon nap in there? It could have been much, much worse," Ms Turnbull said.
She had been in a house fire before and the globe incident had given her "a hell of a fright", she said.
Fire safety officer Barry Gibson said the Fire Service in Dunedin was advised of about three or four fires caused by magnified sunlight each year and there were likely to be many more that were not reported.
Glass paperweights, vases, mirrors and any form of curved glass could all be fire hazards, usually in the winter months, but this incident showed it could happen at any time of the year.
Glass was a silent danger many people did not consider a threat and if people knew a particular room was a suntrap, they should move reflective items out of direct sunlight.
"You shouldn't underestimate the power of the sun and I strongly advise people not to put anything reflective in its way that can magnify the intensity of sunlight," Mr Gibson said.
Ms Turnbull said she wanted other families to be aware of the danger.
"This is something parents give their kids and put on the windowsill because it is pretty, but it goes on fire so easily."
