What Is an IC Rating? (And Why It's Necessary for Recessed Lighting)

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If you have recessed lights in any room in your house, you need to be aware of their IC rating — because these lights could be dramatically affecting your energy bill.

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So, what are IC ratings, and how do you tell whether or not you have IC-rated recessed lighting? Here's an in-depth guide on what you need to know about this important light feature.

What Is An IC Rating Exactly?

Many believe the letters "IC" stand for "insulation contact," but they actually stand for "insulated ceiling." Code requires IC-rated recessed lighting for any insulated ceiling. In addition, many IC fixtures are also airtight and are rated ICAT ("AT" standing for "airtight"), and they are the gold standard for energy efficiency when it comes to recessed lighting.

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If you're planning to install lighting in an insulated ceiling, you need IC-rated fixtures at a minimum, but ICAT fixtures are better. If you have existing recessed lighting that isn't IC-rated, you should consider replacing it if you want to lower your energy costs.

The Problems With Non-IC-Rated Fixtures

Recessed lighting fixtures are sometimes called can lights or downlights. The canisters (cans) that hold the lights extend upward beyond the ceiling into the attic, leaving an opening flush with the ceiling from where light radiates. Non-IC-rated cans have a single wall that gets very hot when the lights are on, so they can't be in direct contact with insulation because they could ignite it. That fire hazard is the first problem with Non-IC rated fixtures, which code addresses by requiring a 3-inch noninsulated space around each light.

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In an effort to partially mitigate the heat buildup, manufacturers include holes in the cans of non-IC-rated light fixtures to allow heat from the bulb to dissipate, and that creates the second problem. The holes, uncovered by insulation, provide a direct path for room air to pass into the attic (which isn't energy efficient).

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It's possible to construct enclosures for the cans from nonflammable materials to partially seal them, but that could cause overheating, particularly if homeowners use high-heat halogen bulbs for brighter lighting. All told: It's a much better idea to retrofit non-IC-rated lighting fixtures with ones that have an IC rating.

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The Difference in Fixtures With IC Ratings

IC-rated can lights have two walls with an insulating layer of air between them. The outer wall never gets hot enough to ignite insulation, so there's no need to leave a space around an IC-rated recessed lighting fixture. It can be in direct contact with fiberglass, rock wool, and even loose-fill cellulose and can be completely covered over with the insulation. In addition, an IC-rated fixture has a thermal switch that shuts off the light in the event of overheating and keeps the light off until the fixture has cooled down.

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ICAT fixtures are constructed with fewer holes, so heat transference through the ceiling drywall is kept to a minimum. To install one, an electrician needs access to the attic to be able to attach the wiring harness to a joist. When that's complete, the fixture itself can be inserted through a pre-cut hole in the ceiling and connected to the harness. Some ICAT fixtures are designed to simply snap together. The process is easier during new construction when the ceiling is uncovered, but it isn't much more difficult to accomplish during a remodel when the drywall is already in place.

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Even though it has minimal impact on an insulated ceiling, an ICAT recessed lighting fixture still allows heat loss into the attic through the gap between the flange surrounding the can opening and the ceiling drywall. This problem is easy to address by applying a bead of caulk to the underside of the flange.

How to Identify IC-Rated Lighting Cans

If you have existing recessed can lights, you may not know whether or not they are IC-rated, but there's an easy way to tell:

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  • Remove the cover from the fixture if there is one and look at the inside of the can.
  • If it's white, the fixture is non-IC-rated, and if it's silver, the fixture is IC-rated.
  • If you remove the bulb, you should see the letters IC or ICAT imprinted on the inside of an IC-rated can.

You can also distinguish between an IC- and non-IC-rated fixture from the attic because the outside of non-IC-rated cans are white, while those of IC-rated fixtures are silver, and the letters IC or ICAT sometimes also appear on the outside of the cans of IC-rated fixtures. If a can is covered by insulation, a telltale sign that it's not IC-rated is a glow through the insulation, which occurs as light shines through the holes in the can. You won't see any light coming from an IC- or ICAT-rated can. If you see this glow, by the way, it's important to pull insulation away from the fixture and create a 3-inch uninsulated space around it.

What Bulbs Do You Need for Recessed Lighting?

Most recessed lighting fixtures accept bulbs with standard E 26 screw bases, although some might take bulbs with smaller E 17 bases, and still others may require bulbs with twist-lock pins.

When it comes to types of bulbs, there's a choice among incandescent, compact fluorescent (CFL), and LED. LED lights are the most efficient, delivering more lumens of light at a given wattage than CFLs or incandescents while generating less heat, thus decreasing the possibility of overheating. These days, dimmable LED bulbs are commonplace and can be used with a dimmer switch for atmospheric lighting.

The shape of the bulbs can affect the quality of lighting from recessed lighting fixtures. Bulbs with the standard light bulb shape, known as A-series bulbs, are great if you're looking for omnidirectional lighting, but if you want more focused, less diffuse lighting, there are better options:

  • R-series (reflector) bulbs are shaped like spotlights and have a reflecting material at the base that amplifies light coming from the front. Because the reflector directs light away from the can, it helps prevent overheating.
  • BR-series (bulged reflector) bulbs are an improvement on R-series ones. They have a bulge just above the base that helps focus the light and direct more of it out of the fixture.
  • PAR-series (parabolic aluminized reflector) bulbs have a parabolic shape, and all but the front of the bulb is covered with reflective material. This creates a highly focused beam suitable for accent and artistic lighting.

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