Using CFLs in Light Fixtures

My light fixtures have a maximum rating for wattage bulbs (i.e. 60 watt, etc.). If I change to the energy efficient bulbs (screw in fluorescent) do the recommended wattage ratings still apply? I thought that the wattage rating has to do with the amount of heat that the bulb generated thus creating a fire hazard. The fluorescent bulbs do not generate as much heat as the incandescent bulbs so can I go up on the bulb wattage? The same wattage fluorescent bulbs seem dimmer than the incandescent bulbs. -Ricky

Hi Ricky,

Yes, you can use a compact fluorescent (CFL) bulb that produces more light as long as it doesn’t exceed the wattage recommended for the fixture.

Light bulbs are commonly compared using both watts and lumens. Watts are the amount of electricity used by the bulb while lumens measure the light produced. Light fixtures have a maximum wattage rating to prevent the wiring and area around the fixture from overheating and causing a fire. Since CFLs uses a fourth the electricity of a comparably bright incandescent, they produce far less heat. So you can use a compact fluorescent bulb that gives more light (lumens) than an incandescent as long as it doesn’t consume more electricity (watts) than the fixture recommends.

To give an example, say your light fixture calls for a maximum of 60 watts. A CFL bulb that produces the same amount of light as a 60 watt incandescent bulb (900 lumens) only uses around 15 watts of electricity. So you can put a CFL in the fixture that equals the light output of a 100 watt incandescent (1,600 lumens) and still only use 25 watts of electricity.

When comparing the light output of the two types of bulbs, remember that it takes CFLs a few minutes to reach their peak light output. More information on compact fluorescent light bulbs can be found in our article CFL: A Bright Idea for Going Green.


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Backed by his 40-year remodeling career, Danny served as the home improvement expert for CBS’s The Early Show and The Weather Channel for more than a decade. His extensive hands-on experience and understanding of the industry make him the go-to source for all things having to do with the home – from advice on simple repairs, to complete remodels, to helping homeowners prepare their homes for extreme weather and seasons.


  1. It’s true the CFL only uses 15 watts, however you are paying for 25 VA of electricity. In other words you are not getting your moneys worth. These CFL bulbs have a very high power factor, and requires more electricity to run the transformers inslde the bulb that it can product.

    Also it is recommended that you call HazMet if you break one of these new fangled, over priced piecs of junk.

    The ‘Old’ Incandescent you got what you paid for 100 watts is exactly what you get. Not so with this scam of the CFL.

  2. Phil is right, Mark. You say a 15 watt bulb takes 25 volt-amps? Rubbish. A watt IS a volt-amp. 1W = 1V x 1A. Look up the definition of watt. A watt is also the unit of power, so saying that a CFL bulb has a high power factor means nothing. A 15 watt CFL bulb takes 15 watts of power. A 100 watt incandescent bulb takes 100 watts of power.

  3. I’ve heard the power factor argument before, but in this context it’s bogus. Even if you were right, with an incandescent most of the energy is turned into waste heat. I’d rather pay for 25 watts and get 15 watts worth of light then pay for 100 watts and get the same amount of light.

  4. I have a chandelier that uses 6 candle based bulbs in it, I have replaced the incandescent ones with CFLs but one of the CFL bulbs has blown out. Can I put in an incandescent until I can get a new CFL bulb. In other words can they be combined.

    • Hi Bronwyn,
      As far as I’m aware, they could be combined. Keep in mind tjat CFL bulbs are not dimmable unless they say they are on the package.

  5. have a chandelier that uses 9 incandescent bulbs, I have replaced the incandescent ones with CFLs but chandelier will not turn on unless I replace one of CFL bulb with an incandescent one . I am using X10 Dmmer switches, and the CFLs are dimmable, Is there a way to fix this problem so I can have all bulbs CFLs.

  6. I have had VERY poor experience replacing incandescent bulbs with CFLs in enclosed fixtures (globes, school house lights, etc.). They burn out very quickly which suggests to me that they are more sensitive to overheating than incandescents. The wattage of the CFLs is much less than the wattage of the incandescents that they replaced.

  7. well something is wrong with these CFL’s. I took a 40 watt incandescent bulb in a light fixture and plugged it into my little watt/amp energy miser device and what did I discover? The 40 watt bulb ran at 38 watts I replaced it with a 23 watt (60 watt equivalent) and it ran between 78 and 86 watts depending on how long I let it sit and the brighter it got the wattage used increased. Well well well, I find this very interesting indeed. Why is it that the bulb is rated at 23 watts and it used 80 watts? more or less.

  8. Is it possible to rewire an exterior light fixture component to be able to install larger wattage (100) bulb? There is currently 12 gauge Rolex in the recepatcle

  9. I replaced 60 watt blubs in my chandelier with 60 watt replacement CFL and now my light hums when I turn it on. there is no dimmer switch. Just a switch. Do I need to use a 40 watt replacement blub instead of 60?

  10. We have acquired a new light fixture with 3 mini spot light. 50 was too strong but 35 is not quite strong enough. Is it safe and ok to mix one 50 with two 35?

  11. My 6 light chandelier calls for 60 watt bulbs. I just purchased mini lampshades. Do think I should adjust the wattage so the shades don’t burn? I was thinking of putting 25 or 40 watt LED bulbs.

  12. I have several ~20 year-old, outdoor, molded-plastic Christmas decorations including Nativity scene figures and Santa items. Each uses 40 watt incandescent light bulbs. I have tried replacing the incandscent bulbs with CFL but none work at all. I’m not talking about slow or flickers – no light at all. I know the circuits and wiring are fine and so are the CFL bulbs, but can’t seem to replace these incandescent bulbs with CFL inside these decorations. I don’t think that the fuses should matter. Please let me know what you recommend as my Christmas decorations are currently consuming ~2 kW every hour.

  13. I just bought a lamp that has 5 bulbs in it. It says “40W max incandescent, 11W max CFL”. This makes no sense to me…the wiring in the lamp is what it is and it must be rated to allow up to 40W of power, regardless if a CFL or incandescent is in there, right?

    We only have 14W and 23W CFLs in the house right now and I don’t feel like going back out to buy 5 new lights.


    • I’m with you Kristin. Lamps are rated based on the amount of power (watts) they draw. You should be able to use brighter CFL or LED bulbs as long as it doesn’t draw more watts than the lamp is rated for, but you might want to contact the lamp manufacturer to see if there’s a reason they’re rated like that. If there is, let us know what the reasoning is.

  14. I have had a similar experience as Guy in replacing 40W incadescent bulbs with CFL or LED. I have a desk light that came with an incadescent bulb in it. The lamp works fine with incadescent bulbs of various wattages. However, when CFL (10W, 13W) or LED bulbs are installed, they do not light at all. I have checked the new bulbs in other lamps and they are fine. As mentioned above the lamp where they don’t work is fine with incadescent bulbs. It has a in-line switch that says 6A 125V AC; 3A 250V AC; 3A 125 VT. I don’t see a wattage rating on the screw-in bulb receptacle. Why don’t the CFL or LED lights work in this lamp? I want to keep it because it has a stained glass shade. Why don’t the new style bulbs work?

  15. I have 1960 ceiling light covers, the flat plate type. I am wondering what watt light bulbs I can use. The ceiling fixture has 3 bulbs. Would 60 watts be too much? I don’t want to over heat the glass cover and break it.
    Thanks, Teri

  16. Teri…remember that one of the reasons why CFLs use so much less electricity is because they are more efficient at turning that electricity into light, with much less wasted as heat. A 13 Watt (60 Watt equivalent) CFL bulb will emit much less heat than a 60 watt incandescent.

  17. Kristen, Ben – The reason for the wattage downrating on the lamps is probably for current protection, not for power consumption. The problem gets into questions of power factor, real power, and reactive power.

    The wiring in the lamp doesn’t care about the power that the lamp draws, only how much current it has to pass through it. If the current is excessive, then the wire overheats and makes a fire. Now, a simple remembered formula is Power = voltage x current (Watts = Volts x Amps), but unfortunately, this is only true for DC. AC gets more complicated….

    The voltage and current in an AC circuit are varying up and down 60 times per second. The real power that a circuit uses (the power you pay for) is only the part where the voltage and current are in phase with one another. Out of phase power (reactive power) is delivered to the circuit and then returned to sender, so you don’t have to pay for it, but the wiring still has to deliver it.

    Incandescent light bulbs use no reactive power, they are simply resistors, so 40W delivered = 40W consumed. CFLs, though, have reactive components such as capacitors and inductors that make them work, so they store energy and return it 60 times per second. They can have a power factor of 0.4 or 0.5, which means that 22W delivered = 11W consumed + 11W returned to the grid. You only pay for what’s consumed, but your lamp still has to deal with the total.

  18. Joan, Guy – The reason your lamp may not work is it may have internal circuitry that changes or reduced the voltage (or even converts it to DC). Incandescent bulbs are fairly insensitive to this since they are basically a piece of wire, but CFLs are complicated circuits and can be picky about their input.

  19. Joel Keene, how many watts does a 23 watt cfl (100 watt equivalent) lamp actually have running through it before returning some to the grid? I am concerned because I am putting one of those bulbs into a 60 watt max ceiling light fixture that is not recessed, but is very enclosed by a glass dome. I just don’t want a fire.

  20. Hello,
    We bought a house with a kitchen ceiling fixture which has two 4-pronged CFL bulbs (they look like 4 tubes about 6inches long) They are 26 watts each. I would like to bump up the wattage (if safe) is there a safe higher wattage bulb available?

  21. We have two light fixtures in the kitchen. They each take four bulbs. We mixed wattages when we put in the CFLs 27 months ago (we write the date on the bulb when we put them in the fixture). Each fixture has two 23w bulbs and two 13w bulbs. All four 23w bulbs have burnt out. The four 13w bulbs still work. Why did this happen? Is it a problem to mix bulbs of different wattages? (They were all new GE bulbs.) The CFLs have a shorter life in these fixtures than did the old incandescents. We hope you have an answer for us.

  22. I installed a CFL dimmer switch and put dimmable CFL’s in my chandelier. Problem is the dimmable CFL’s are taller than the cylinder globes by a full inch. I am seeking a creative solution as going to a lower watt dimmable CFL would not provide sufficient illumination. Thanks!

  23. I have a 3 prong chandelier that I want to switch regular bulbs to the LED natural daylight bulbs. I can use up to 100W, however, I can only find a 60W and 40 W bulbs. Can I leave one of the prongs empty?

  24. Why do some light fixtures have different wattage ratings for incandescent and CFL lamps?

    It would seem that heat is heat and current is current and the type of “bulb” would not make a difference.


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