60 degree C wires
#1

I bought a light fixture for my hallway to update the decor. the box says that homes built before 1985 may not have wires that are certified for 60 degrees C. How would I know if my wires are or not, and what difference would it make?
#2
It is difficult to tell unless you can read the letters on the sheath of the cable entering the box, or know the age of the wiring install. 60 degree wire will say NM on the sheath. 90 degree will say NM-B.
The rating has to do with the operating temperature the insulation can withstand.
The rating has to do with the operating temperature the insulation can withstand.
#3
Try to find some area of your house where the cable may be exposed, such as an unfinished basement, crawl space, garage, or attic. Look carefully at the cable to see if it says "NM" or "NM-B". It can be hard to read -- often just embossed in the sheathing.