How to change a ceiling light fixture


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Aug 08, 2023

How to change a ceiling light fixture

Q: I want to replace a ceiling light fixture. How do I do it? A: Switching out a ceiling light fixture is often fairly simple: Turn off the power to the circuit, climb a ladder and remove the old

Q: I want to replace a ceiling light fixture. How do I do it?

A: Switching out a ceiling light fixture is often fairly simple: Turn off the power to the circuit, climb a ladder and remove the old fixture, then connect the new fixture’s wiring and base, screw in the bulbs and add a shade. Restore the power and flip the switch. Voilà! A whole new feel for the room.

But it’s not always so straightforward, especially if you have a house built before the mid-1980s and buy a flush-mount light fixture, only to discover a warning on the back: “Risk of fire. Most homes built before 1985 have supply wire rated 60 degrees [Celsius]. Consult a qualified electrician before installing.”

The issue is that earlier wiring was designed to withstand temperatures only up to 140 degrees Fahrenheit, the equivalent of 60 degrees Celsius. A fixture fitted with bulbs close to the ceiling can become significantly hotter, especially when high-wattage incandescent bulbs are used in an enclosed fixture. The heat degrades the insulation wrapped around each of the wires within the cable, making it brittle and crumbly, greatly increasing the risk of a fire. So newer wiring is designed to last even at 90 degrees Celsius (194 degrees Fahrenheit).

If you’re not sure what kind of wiring you have, check the attic, assuming the fixture you want to replace is on the top floor. If the cable feeding that ceiling box is insulated in cloth, it’s the old standard. If wiring cables are encased in plastic and it’s stamped “Type NM,” for nonmetallic, it’s also made to the old standard. If it says “Type NM-B,” it meets the new standard.

If you have old-style wiring or you don’t know the age of the wiring and it’s not easy to check, then you might think the simplest solution would be to use LED bulbs, which stay cooler than incandescent bulbs. But later occupants might not realize the necessity of using cool-running bulbs.

To avoid future hassles and the risk of a fire, have an electrician install a junction box at least three feet away from the ceiling box and end the old wiring there, with a short run of Type NM-B wiring to the ceiling box. You don’t need to replace wiring farther away from the ceiling light, because those areas won’t get such intense heat. But where there is no attic above, adding the new box will involve cutting into and patching the ceiling.

If you don’t want to retrofit wiring near the light, there are plenty of other options, but they all start with returning the fixture that has the warning. If you need a fixture that fits tightly to your ceiling, you can purchase a “maintenance-free” flush-fitting light that comes outfitted with non-replaceable LED bulbs. When the bulbs dim, you replace the fixture; this is wasteful but safe, and it’s also less expensive than hiring an electrician and patching the ceiling. You can also buy a fixture that takes a circular LED bulb or a screw-in style that doesn’t exist in incandescent bulbs, thus eliminating the possibility that someone might switch to one that would overheat.

If you don’t need a flush-mount fixture, you can probably avoid the wiring issue altogether. Semi-flush fixtures, which hang down about four to six inches, have a greater ability to disperse heat from bulbs, especially if the bulbs are shielded only below or not at all, rather than being enclosed. Chandeliers release heat even better.

Apart from the wiring issue, there are a few other factors that can complicate switching out a ceiling fixture. Save on trips to the hardware store by inspecting your old fixture before shopping. You’ll need to shut off your power at the circuit breaker and loosen the base enough to see how it’s attached. Some fixtures have a ring with curved slots, and others have a bar or a pair of bars that form an X. Some depend on a threaded rod that hangs in the center. Try to find a replacement light that uses the same installation system or has attachment hardware that would be easy to install on your ceiling box. Also consider the weight of the new and old fixtures. If the new one weighs more than 50 pounds, you may need to replace the ceiling box with one rated for ceiling fans.

When you go to install the new fixture, replace the mounting hardware, if necessary. Make a temporary hook from a metal coat hanger by using pliers to cut off the angled wire on one side and to shorten the other side to 10 inches or so. Bend that end into a hook. Then you can hook the hanger to the mounting hardware and use the hook to hold the base of the new fixture close to the ceiling while you attach the wires.

Unless you have a metal ceiling box connected to a ground wire (bare copper, typically held by a green screw), attach the light fixture’s bare wire to the mounting hardware using the special green screw made for this purpose. (A typical wood screw won’t hold the wire securely enough.) Then attach the fixture’s live and neutral wires as shown in its instructions.

The fixture’s wires will probably be stranded — a bundle of thin wires encased in insulation. Use a wire stripping tool to pare back about ¾ inch of the insulation. The house wiring is probably a solid, thicker wire. It should be stripped back ½ inch, so snip the wire or trim the insulation as needed to get to that length. By hand, wrap the stranded wires tightly around the solid wire, then twist on a wire nut until the connection is tight.

Once the wires are connected, fold excess wiring neatly, so it fits into the ceiling box. From there, it should be simple: Install the base, add the bulbs if needed, and put on the shade if there is one. Restore the power, then switch on the light.

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