Firefighters were called to a house on Friday evening after a downlight overheated and set on fire.
Mitcham Fire Station was called to the semi-detached house in Dorset Road, Wimbledon, at 7.15pm.
The fire set a pair of bedroom curtains alight before firefighters extinguished it.
Fire damage was contained to the corner of the bedroom.
No-one was injured.
Downlights are light bulbs set in metal cylinders mounted into ceilings which direct beams of light downward.