Recessed Lighting Safety

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How to protect your home from fire hazards from recessed lighting fixtures and thermocouple replacement.

Recessed lighting has been a part of many homes since the 1970s. Currently Underwriters Laboratories (UL) has a list of approved features for lighting safety. Older recessed lights in your home may require special attention if you are installing new insulation or higher wattage bulbs than the fixture is rated for.

Fire Hazard

The surface temperature of an incandescent light bulb can be hundreds of degrees. Newer compact fluorescent bulbs also generate heat at the base where the sensitive electronics are contained to control the voltage to the bulb. Light fixtures must dissipate to prevent premature bulb failure or fire. Certain light fixtures are made to come in contact with insulation, but you must know for certain this is the case.

Many residential fires have resulted from improperly installed or modified recessed light fixtures. On occasion, homeowners have mistakenly covered older fixtures with insulation in an effort to reduce energy costs. This insulation traps the heat created by the bulb. This heat, in turn, can either melt the insulation on the electrical wiring or ignite combustible materials near the fixture.

After the energy crisis in the late 1970s, UL responded to the increase in homeowner applied insulation.

UL mandated that recessed lights be equipped with a safety override switch within the fixture. This switch would sense when the light fixture was trapping too much heat and the safety switch would simply turn the light off automatically. Once the fixture cooled down, the light would then turn itself on. This device is commonly referred to as an integral heat thermocouple, or simply a thermocouple.

The popularity of vaulted ceilings in the 1980's created another problem. Recessed lights were installed in roof rafter spaces where insulation was absolutely necessary. However, the code and the lighting manufacturers said not to put insulation within several inches of the fixtures. Every recessed light location became a hole in your ceiling that let unconditioned air in year round.

In Contact Fixtures

UL developed guidelines that allowed manufacturers to build recessed light fixtures which could be completely covered with insulation. These fixtures carry an IC designation which stands for “In Contact.” The fixture will be labeled as such and some IC fixtures will also have IP, which stands for Inherently Protected. IP fixtures have the thermocouple discussed previously.

IC fixtures usually use lower wattage light bulbs, under 100 watts and most commonly a 75 watt maximum. This is because the insulation covering or abutting the fixture will trap way too much heat from the higher wattage bulbs.

Besides the IC and IP fixtures, the other common residential fixture is ICAT, which stands for “In Contact Air Tight.” These fixtures are primarily used in bathrooms inside shower stalls or above a bathtub.

Replacing a Thermocouple on a Recessed Light Fixture

If you have noticed that one or two of your recessed lights turn off occasionally, you may have a defective thermocouple. Thermocouples are small, tubular fixtures that get wired in between the electrical feed to the recessed light, and when the heat builds up, they turn the light off to prevent damage to the wires. You may want to inspect the insulation around the light fixture if it is accessible from the attic. If the insulation is at least 6 inches away from the light, then thermocouple needs to be replaced. If you have a CFL installed in the fixture, it may be defective or there may be heat built up inside the fixture causing the internal safety in the bulb to shut off power.

You will most likely need to remove the old thermocouple before and take it to an electrical or lighting supplier to make certain you have the correct one.

Wear eye protection since there will be dust, debris from the drywall, and possibly insulation that can fall out of the opening when you remove the trim kit.

Before you begin working on the light, shut off the circuit breaker that is supplying the light fixtures or place a piece of electrical tape over the light switches while they are in the “OFF” position to prevent any accidental activation. In most cases it is better to turn off the power at the breaker.

Remove the light bulb from the fixture and locate the internal junction box. On the side of the box you should see a small tubular object that looks a little like a fuse holder. That is the thermocouple.

There will be two wires coming off of the thermocouple. Typically there is a black and blue wire. One wire is connected to the electrical feed and the other is connected to the wire coming from the light socket. There may be wire nuts in place already, but usually they are hardwired into the fixture and you would have to cut the wire with wire strippers or pliers.

The thermocouple is usually held in place with a small metal clip on the side of the box. Take it to your local electrical supplier and pick up a replacement.

Replace the thermocouple and connect the black and blue wires to the thermocouple wires. Wrap the wire nuts with a piece of electrical tape. You should attach the black thermocouple wire to the wire coming from the black electrical supply wire.

Replace the junction box cover; install the light bulb; turn on the circuit breaker and then turn the light switch back on. The light should no longer go off intermittently.

For more information on light fixture classifications and markings go to the Underwriters Laboratories document linked below.

UL Markings



Posted on Oct 14, 2010
Posted on Sep 13, 2010
Randy Gordon
Posted on Jun 21, 2010