In article , Twayne wrote:
Say you've got an old circa 1954 ceiling light fixture. Spec'd for 2
max 40 watt incandescent bulbs.

My Sylvania 100w-output CFL's take 23w input.

100% safe to use 2 of these CFLs instead of 2 40w incandescents??

Thx,
Cathy

As long as the INPUT wattage is within the fixture's rating you are
fine. If the fixture is rated 40 W, then up to a 40 W INPUT lamp can be
used. The output equivalence is irrelevant in this respect.

CFLs are more efficient at producing non-radiant heat than
incandescents. I have found a 42 watt CFL to heat a fixture up very
slightly more than a 60 watt incandescent did.

Incandescents produce a lot of IR, which becomes heat but the IR mostly
escapes the fixture before becoming heat.

- Don Klipstein )