The kitchen or living room recessed lights work fine when you switch them on, then one or more goes out after twenty minutes or an hour. A while later it comes back on by itself. Then it happens again. This is one of the most specific symptoms in residential lighting, and it almost always means the same thing: the fixture is getting too hot, and a safety device inside it is switching the light off until it cools.
The thermal protector
Many recessed fixtures, especially older incandescent and halogen cans, have a thermal protector: a small switch that opens when the fixture gets too hot and closes again when it cools down. As the IAEI's review of recessed luminaire requirements explains, the protector is not supposed to cycle in normal use. It is there to catch abnormal conditions, and one of the conditions fixtures are tested against is a bulb of higher wattage than the fixture is marked for. So if a recessed light is cycling, something is making it run hotter than it was designed to.
What makes a recessed light overheat
- A bulb that is too big. The label inside the can gives the maximum wattage and the bulb type. An older can with a higher-wattage incandescent or halogen bulb in it is the single most common cause.
- Insulation where it should not be. Fixtures not rated for contact with insulation (non-IC) need clearance from it. The National Electrical Code and the fixture's listing set those clearances. Insulation blown or pushed over the top of a non-IC can traps its heat. This often follows attic work or re-insulating.
- The wrong bulb shape. A bulb that sits too close to the protector, or a reflector bulb in a can designed for something else.
- A hot attic. In a Miami summer, attic temperatures add to everything. A fixture that is marginal in winter can start cycling in August.
- A failing protector or connection. Less often, the protector itself has worn out, or a loose connection in the fixture is making heat of its own.
What you can safely check
- Read the label. With the light off and cool, look inside the can for the label giving the maximum wattage and bulb type. Compare it to the bulb that is in it.
- Try a lower-wattage LED. A correctly sized LED bulb or LED retrofit kit listed for that fixture makes far less heat. Often this alone stops the cycling.
- Note which lights cycle. One fixture, several in one room, or all of them? Cycling in a group under the same attic area points to insulation or attic heat.
Do not bypass the thermal protector or tape over it, and do not move insulation around live fixtures in the attic. The protector is what is keeping an overheated fixture from damaging its own wiring or the framing around it.
When it is not heat
If the lights go off and on in a random way, flicker, or all lights on one switch drop out together, the cause is more likely a loose connection, a failing switch or dimmer, or an LED and dimmer that do not get along. See LED lights flickering on a dimmer and lights flickering throughout the house.
How it is fixed for good
- Correct bulbs. The right wattage and type for the fixture.
- LED retrofit. A listed LED retrofit module or trim made for that can size. It replaces the hot source with a cool one and usually improves the light.
- Restoring clearances. Pulling insulation back from non-IC fixtures, or replacing them with IC-rated fixtures where insulation must stay in contact.
- Replacing the fixture. Where the can is damaged by heat, the protector has failed, or the wiring at the fixture is brittle.
Our lighting repair page explains the visit, including recessed lights that cut out.
Questions people ask
Is a recessed light that keeps turning off dangerous?
The protector is doing its job, which is good. But the fixture is running hotter than it should, often for hours every day, and that heat ages the wiring and the materials around it. It should be corrected rather than lived with.
Will an LED bulb stop it?
Very often, yes, if the cause is the bulb's heat. If the light keeps cycling with a correctly sized LED, the cause is something else and the fixture should be checked.
Kitchens, bathrooms and high ceilings
Cycling is most common where several recessed lights run for hours at a time, such as kitchens and family rooms, and where the space above the ceiling is an unconditioned attic. Bathroom fixtures over showers have their own requirements for damp or wet locations, and a fixture not suited to the location can fail early. High ceilings make bulb changes harder, which is one more reason to move to a listed LED retrofit that runs cooler and lasts much longer.
Can I put an LED retrofit in any old can?
Use a retrofit listed for the can size and type. The listing and the instructions say which fixtures it can be installed in.
Need it looked at?
KRW Electric (EC13012832) troubleshoots and repairs recessed lights that cycle or cut out in Pinecrest, Coconut Grove, South Miami and Miami Beach, with same-day service when scheduling permits. Call (305) 359-7312 and tell us what you are seeing. We will ask a few questions, tell you whether it sounds urgent, and give you the earliest time we have. Our before you call checklist covers what to have ready, and what happens on a repair visit explains the rest.
Reviewed by Kyle White, KRW Electric Company LLC — licensed electrical contractor EC13012832.
