Recessed Light Turns Off by Itself, Then Comes Back? That's the Thermal Cutoff

The light is telling the truth

A recessed light that runs 20–30 minutes, quits, then sheepishly comes back once it cools has tripped its thermal protector — a small heat switch every modern can fixture carries. It exists because recessed cans live in ceilings surrounded by wood and insulation, and an overheating fixture up there is how attic fires start. So before anything else: the cutoff isn't the problem. The heat is the problem. Your job is to find the heat.

Suspect #1: the bulbs

Inside the can, on a label, the fixture states its maximum wattage and often the bulb shape it's designed for. Over the years, bulbs get swapped by whoever had a bulb:

• Too many watts — a 75W bulb in a 60W-max can. Classic.
• Wrong shape — reflector bulbs (BR30/PAR30) direct heat differently than A-shape bulbs; a wrong-shape bulb can cook the socket area even at legal wattage.
• Halogen anything runs ferociously hot in enclosed cans.

The modern fix is beautiful: LED. An LED putting out the light of a 65-watt incandescent makes about 9 watts of heat. Swap the whole ceiling's bulbs to quality LEDs (marked suitable for enclosed fixtures) and most thermal-cycling stories end immediately.

Suspect #2: the blanket on top

If bulbs check out, the can may be smothered. Non-IC-rated cans (common before the 90s and in cheap remodels) must have clearance from insulation — they cool by airflow. Attics get re-insulated, blown insulation drifts, and one day the can that breathed for 20 years is buried under a foot of cellulose.

From the attic (carefully — cans can be burn-you hot): IC-rated cans can be covered and are labeled IC; non-IC cans buried in insulation need the insulation pulled back to about 3 inches — or better, replacing with modern fixtures, because "loose insulation held at a distance" is a promise attics don't keep.

The upgrade worth knowing about

Modern sealed LED retrofit modules replace the can's guts (or the whole can) with a one-piece LED unit: airtight, IC-rated, insulation-contact safe, 90% less heat, and typically rated to outlive your roof. An electrician can convert an entire ceiling of temperamental old cans in an afternoon. If your house has more than a couple of cycling cans, that's the grown-up fix — solves the heat, the energy, the bulb-buying, and the "who keeps putting 75-watt bulbs up there" problem all at once.

What not to do

Don't bypass the protector (yes, people do; some of their houses made the news), don't "just crack the trim open a bit" for airflow, and don't keep feeding it bulbs while it keeps cycling. A safety device in a loop of constant tripping is a safety device asking you to fix the actual problem.