In other words, this isnt about the physical size of the light bulb.
This is about the highest safe wattage, because the safety in question is preventing a fire.
Why This Is Important
Many fixtures have a maximum wattage rating.
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In newer fixtures, thats usually 90 degrees Celsius or 194 degrees Fahrenheit.
Thats as much heat as the wiring can tolerate and remain flexible and safe.
In older fixtures, the temperature limit for the wiring may be 60 degrees Celsius.
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Thats a good deal lessonly 140 degrees Fahrenheit.
Always follow maximum wattage ratings.
How Can I Tell?
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But that still leaves the question of the highest safe wattage open.
General Assumptions and Rules of Thumb
The maximum safe wattage of a fixture depends on three factors.
One is how much heat a given light bulb generates.
Another is the maximum heat tolerance of the wiring used in the fixture.
The third is how enclosed or launch the fixture is.
Table lamps andfloor lampsthat have an open-top shade, or no shade at all, are among these.
Atorchiere floor lampthat takes a high-intensity halogen bulb is a prime example.
These fixtures may not come with a maximum wattage limit.
It will be higher if the fixture is open, and especially if its open on the top.
Open-sided fixtures which are mounted flush to the ceiling are more restrictive than closed flush-mount fixtures.
What About the Incandescent Equivalent Rating?
Heres something you could safely ignore.
you’ve got the option to ignore the reference to 60 watts.
Thats shorthand for Produces approximately the samelumensas a 60-watt incandescent bulb.
What is important is the power the bulb uses: in this case, the 14 or 15 watts.
Whats the Bottom Line?
If it doesnt have a rating, err on the conservative side.
And if its an older fixture that may not have modern wiring, be even more conservative.
Second, follow the guidelines above to choose bulbs for fixtures that dont have a rating label.
Finally, consider the heat that the bulbs youre considering emit.
LEDs (including the increasingly popular LED tubes) are the coolest.
