Heat marks and dust halos
Halogen downlights, older oyster lights with incandescent globes, and fittings with too big a globe inside can heat the ceiling around them for years. The paint yellows first, then browns. If the plaster looks scorched, cracked or brittle, the fitting has been running too hot, and the cable and lampholder above it have been cooking too.
A softer grey or brown ring can simply be dust. Warm air rising around the fitting carries fine dust and cooking residue, which settles on the cooler ceiling at the edge. It wipes off or comes up with fresh paint, and doesn't mean the light is faulty. A ring that is darker on one side, smells hot or comes back quickly after painting is worth having checked.
Water stains look different
Water marks are usually irregular, with a darker tide line at the edge, and they may spread away from the light rather than circling it. The plaster can feel soft or start to bubble. Common sources are a roof leak, a shower or pipe upstairs, condensation from an exhaust fan duct, or an air conditioner or evaporative cooler in the roof. Water and a light fitting together is a safety problem, not a cosmetic one.
What should happen to the fitting
A fitting that has scorched the ceiling should be replaced rather than given a cooler globe, because the heat damage to its lampholder and cable is already done. A complete LED fitting runs much cooler, and an IC-rated one can sit under insulation. If insulation is touching an old halogen fitting or its transformer, tell your electrician, because that adds to the heat risk.
Replacing a fitting is electrical work for a licensed electrician, who will check the cable above it while it's open and issue a Certificate of Electrical Safety.
What you can safely do now
- If there is water near the light, switch it off and turn that circuit off at the switchboard if it is safe to reach.
- Stop using a light with scorched, cracked or brittle plaster around it.
- Photograph the mark and note whether it has grown, or appeared after rain or a shower.
- Don't climb into the roof space to look. There is live cabling up there.
Services that can help
Read more in our guides
Related questions
- Water is dripping from a light fitting. What should I do?Don't touch the light switch, on or off.
- Why do my light globes keep blowing?Globes that fail early usually have help.
- Why do my LED lights buzz or hum?Most buzzing LEDs come from a mismatch rather than a fault: a dimmer built for old halogen globes, an LED driver that doesn't suit the dimmer, an old transformer left in…
- One downlight has stopped working. Is it the globe or the fitting?Check whether it has a removable globe.
Sources for this answer
1 source, with the date each was checked
- 1.Energy Safe Victoria: Whenever a licensed electrician completes any electrical installation work, they must provide a Certificate of Electrical Safety (COES). Accessed 30 September 2026.
General information for homes in Victoria. Every installation is different, so treat this as a starting point. Where this answer refers to Victorian safety or rental rules, the sources above have the current requirements.