One of the easiest and aesthetically most effective updates you can make is to change outdated light fixtures. The dramatic impact of carefully deployed lighting can be magical.

When Susan and I chose new lighting for our 1979 home, we had to be careful when selecting the fixtures. That’s because many of the light fixtures sold at lighting showrooms today cannot be safe electric wire and cablesafely installed in most houses wired before 1985. These fixtures are clearly labeled with a warning that reads:

“For supply connections, use wire rated for at least 90 degrees C.”

Fixtures with this label are a fire hazard when installed on pre-1985 wiring. They generate enough heat to damage the insulation on older wires. Wire manufactured after 1985 has coverings that can withstand the higher temperature.

So, if you know your wiring was installed before 1985, don’t use fixtures requiring 90-degree–rated supply wires.

If you aren’t sure, confirm that you have 90-degree–rated supply wire. Check the cable jacket or wire insulation.

On plastic sheathed cable, look for the letters NM-B or UF-B printed on the sheath.

If your wiring is fed through conduit, look on the wire insulation for the letters THHN or THWN-2.

If you’re not sure, play it safe. Call an electrician or do what we did: choose a fixture that isn’t labeled with a supply wire temperature requirement.