clock menu more-arrow no yes mobile

How to Safely Replace a Ceiling Light

Ask This Old House master electrician Heath Eastman clarifies the temperature rating system for ceiling lights and then installs one for a homeowner.

Steps for Replacing a Ceiling Light:

Heath starts by explaining why ceiling fixtures are temperature rated and what that means:

  • Houses built before 1985 used wires that could withstand temperatures up to 60 degrees Celsius.
    a. Certain lightbulbs generate more heat than 60 degrees, so over time, those wires could fray and crack, causing an arc, which could create a fire.
    b. After 1985, they changed the code so that wires needed to be rated to withstand temperatures up to 90 degrees Celsius, which is common for most modern fixtures.
    c. To determine which type of wiring you have, look at the cable.
  • Cloth wire is not rated for 90 degrees.
    a. Plastic wire with the words “Type NM” printed on them are rated up to 60 degrees.
    b. Plastic wire with the words “Type NM-B” printed on them are rated up to 90 degrees.
  • Shut the power off at the breaker.
  • Remove the old light fixture using a screwdriver. The wiring will need to be disconnected before pulling it from the ceiling.
  • Push the old wiring out through the box and into the ceiling.
  • Cut a section of the old wiring away from the fixture.
  • Wire the new NM-B cable to the old wiring inside of a junction box.
  • Fish the new cable through the electrical box and mount the electrical box to the ceiling.
  • Wire the new light to the new cable using a pair of pliers and wire nuts.
  • Mount the new light to the electrical box on the ceiling.
  • Turn the power back on.


Heath installed the 12” Oil Rubbed Bronze 2-Light Ceiling Light, manufactured by Hinkley Lighting.

Expert assistance with this segment was provided by Eaton and Eastman Electric.