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Compact Fluorescent
Scott sent this question in (Makers correct me if I’m wrong in my response and/or debate the merits of CFL, you know you want to!)…

Hi Phillip -

I thought you might be able to either answer this question or suggest someone (or somewhere) that could. I have had a hard time getting a straight answer.

I’m no genius when it comes to things electrical. It seems to me like this is something that should become an important part of public knowledge. There are so many reasons to embrace CFLs (compact fluorescent lamps) (like pollution, the cost of oil, global warming and the future of our planet), but if people (like me) remain in relative ignorance, its never going to happen. I guess I’m taking a step in the right direction, but I’m still kind of in the dark (I really did not intend that pun, sorry).

My question is about CFLs, or compact fluorescent light-bulbs (more formally: compact fluorescent lamps)

I bought this lamp at ikea, and near the socket it says to use a maximum 50 watt type R bulb or a 40 watt type A bulb (it says, in far fewer words, that exceeding this rating could cause the whole thing to go up in flames). I assume they mean incandescent. So I bought a CFL to use in this lamp. My CFL is 12 watts, which is equivalent to about 50 watts. My question is: is it safe to use this bulb in my lamp?

Anyway, ikea customer service only said “don’t use a bulb that exceeds the wattage recommendation.” I have emailed GE, Philips and some other big faceless lighting and power companies. So far, no one has returned my reply.

The short answer is yes it will work, the light -output- is equivalent to 50 watts. The CFL just needs 12 watts and that’s what it will get.

Oh, the usual caveats apply – for maximum safety please avoid electricity and only use USDA approved sunlight and stay away from any focusing lens to insure everything won’t go up in flames.

Phillip Torrone

Editor at large – Make magazine. Creative director – Adafruit Industries, contributing editor – Popular Science. Previously: Founded – Hack-a-Day, how-to editor – Engadget, Director of product development – Fallon Worldwide, Technology Director – Braincraft.



  1. jovino says:

    basically, the wattage ratings are to limit the heat output of the bulb. Putting a bulb with a higher max rating will obviously generate more heat, and might cause parts of the lamp to melt or become unstable. Since the heat output of CFLs are negligible, then it won’t be a problem.

  2. abbtech says:

    I would agree with PT. As far as I can tell the rating of the light is based on how much heat it was designed to handle. Since the CFL bulbs generate much less heat you swill be fine.

  3. troycurtisjr says:

    The long answer:

    Really the wattage rating of the bulb is an indicator of how much current it draws. It turns out that the more current the bulb draws the brighter the light output, and yes the more heat it produces. While there may be particular cases where excessive heat would be an issue, this rarely includes the socket.

    The real issue is that the socket can only take so much current. The heat issue does come into play here, however the problem is that too much current going through the socket will cause the socket to get to hot. Anytime electricity goes through wire (or any metal) a certain amount of heat is produced, more current means more heat. So there is a heat issue, just not directly from the bulb.

    Finally, CFL bulbs DO generate much less heat than incandescents. In fact, almost all of the energy savings that you see from using CFLs is from it not producing all that heat. Taking the posters example: The 12 Watt CFL has the same light output as a 50 Watt bulb. You aren’t loosing any light energy, you are just “losing” 38 Watts of generated waste heat! (Approximately)

  4. onlyocelot says:

    To make Troy’s long answer even longer, but to get to the point: the CFL does 12 watts of work. From a 120v AC source, this is (approximately, because I’m not going to look up the physical constants for the ionized gas in the CFL, etc) about 100ma. An incandescent, which does 50W of work on that same 120vac source will draw nearly half an amp. So whatever heat is made in the contacts of the socket will be reduced by about 8 (since heat is an (I^2)*R phenomenon.)

    In short, the power rating on both kinds of bulbs is not related to the light power emitted, but rather the total power produced. The 50W bulb’s light power is rated in lumens (or some other light measurement), and the 12W CFL produces the same amount of lumens as the 50W bulb, while emitting a fourth as much total energy. That’s why it is cheaper to use, and why it is cooler in operation, but produces the same amount of light.

    Now, The real warning is about the bulb itself: some CFLs are just not made to be operated upside down, and so if this lamp holds the bulb upside down, be sure to get one built for it, or its lifetime will be reduced. Part of this is from the small amount of electronics that makes the flourescent start up, which is stored in that white housing between the socket and the bulb, which just doesn’t want extra heat, unless it’s built for it. So read the package, and if it says “not for inverted operation” or some such, choose another. Even still, it won’t be a fire hazard, it’ll just kill the bulb sooner.

  5. onlyocelot says:

    duh. The difference in work done is closer 16 (for a current difference of 4).

  6. d-sier says:

    The real long answer..

    Ok, IKEA is known for saving money, on the production that is…

    If they say 50w is max, you can be sure they have selected the absolute cheapest part that is up to that standard.
    There is no use having a cable that can take 100w if the socket only can take 50w, unless it’s cheaper that is…

    The socket really is the problem, on sockets capable of a higher watt there is a ceramic socket but these are quite expensive to produce, compared to plastic that is.

    The wires in the socket however is not really a problem, they have a conductivity that is equal if not better than the cable leading to it.
    This is for many reasons really, one of the main reasons is that you need a solid connection between the socket and the bulb otherwise you could end up with sparks and all the rest that follows.

    Plastic has two great disadvantage (or advantage if you sell the lamps..).
    1. It ages, the ageing can be accelerated by a couple of things UV light and heat is usually the strongest candidates.
    2. It melts. And that’s not nice…

    The next point is the standard light bulb, it has a metal foot.
    And metals are quite well known to lead heat.

    So the conclusion is that the rating is based on how much heat the socket can take so it won’t melt.

    As an added bonus when using a CFL is that you will reduce the ageing of the plastic and you will end up with a lamp that will be functional longer.

    Ok, I admit…. I have a lamp producer in the family :)

  7. Rostov says:

    Nonsense! Lamp sockets can handle the current for any normal incandescent bulb. The problem is heat, but it is heat generated by the bulb. If you don’t believe that, try touching a 12-watt halogen bulb.

    Typically, the housing around the lamp traps heat, so you don’t want to use a bulb that generates more heat than the fixture can dissipate.

    So back to the short answer: CFLs DO generate much less heat than incandescents, so a 12-watt CFT is safe in a lamp rated for 50-watt incancescent bulbs.

  8. d-sier says:

    Isn’t that what I said?

  9. Rostov says:

    Oops. d-sier got in before me. Good analysis of the socket factor. In addition, the housing around the bulb can affect the socket because it traps heat.

  10. Winston1 says:

    To make this even more important, many places have started to put the end to incandescent bulbs in general. I believe Ontario has plans to be rid of them in 5 years (though that will likely be pushed off to 25 because thats how government works)

    The one thing that CF bulbs won’t generally do is dim, so you can’t use them with you’re fancy dimmer to set “the mood”

  11. rich.thomas says:

    Please note that the currently approved phraseology of Warmist Dogma is now “Global Climate Change” so that any type of atypical weather can be ascribed to GCC.

  12. =mathew says:

    I stick 23W CFL bulbs in 60W-approved sockets. Nothing has caught fire yet.

  13. rripken says:

    Wow, looks like we have some lamp-smart people in the house. I feel dumb asking this, but would there be any reason a 50 watt CFL couldn’t be used in said lamp? Say, something like this 42 watt full spectrum.

  14. jalessio says:

    My understanding is that the information provided on CFL packaging about the equivalant amount of light you would get from an incandescent is just to help you pick out the correct size for the task. Since CFLs are relatively new and incandescents have been around for everyone’s entire lifetimes, most people have an intuitive sense for about how much light is provided by a 100W or 50W light bulb. For instance, when your overhead light in the kitchen goes out you probably know you want something in the neighborhood of 100W because you like a lot of light while you are cooking. You probably know that you want something less than 100W for your bedside reading light, just from experience over the years. It doesn’t necessarily make a lot of sense that this is all based on the amount of energy the bulbs use instead of say, the number of lumens they provide, but for whatever reason our cultural knowledge of how much light comes out of a bulb is based on the wattage of the bulb.

    Now, enter the CFLs and you see something like 12W on the package. Based on past experience this seems WAY too low for the location you had in mind. The CFL manufacturers need a way to explain to you that things have changed, you don’t need to use all that energy to make light any more, but you and I and Joe Consumer would have no idea what it meant if the package stated the number of lumens it produced. Instead, to keep things simple, the CFL package makes a comparison against something you already have an intuitive understanding of – the amount of light from a 50W bulb. It also has the added bonus of making is clear that you are saving 38W and getting the same amount of light by buying the CFL.

    In short, I think you’d typically need a really big CFL to exceed the manufacturer’s recommended wattage ratings for lamp fixtures designed to handle incandescents.

  15. rook999 says:

    Now. Don’t these flourescent lights all have a drop of mercury in them? It seems like we’re solving one problem here, the energy consumption, but when these things are broken or thrown away, we’re putting a LOT of mercury into the landfills and water. This is not a good thing.

    Any suggestions for removing mercury from land and water? Maybe a Makeshift problem here.

  16. philliptorrone says:

    @rook999 – another way to look at it – since a lot of the power for lights in the usa comes from coal, which makes a lot of air pollution, would be decreased it’s one tradeoff for another. i think decreasing power with something as simple as replacing lights is a good step, the mercury can be contained, maybe not now but that can be solved. but conversely there are ways to scrub the output of a coal plant, and there are other sources of power. it’s a good discussion either way.

  17. Fastolfe says:

    IMO, it might help if bulb packaging were standardized to include a similar notice that cars or home appliances have about energy consumption:

    # of watts consumed
    Lumens of light produced
    Efficiency ratio of watts/lumen
    Estimated cost to operate or total joules/kwh of energy used during its expected lifetime

    I think other posters have it right that it’s more about the heat produced electrically than the light output of the bulb. The fixture can only handle so much electrical current and the housing may only be able to handle so much heat produced by the bulb itself. I would have no qualms about putting even a 50W CFL in a socket rated for a 50W incandescent. The current will be the same (what it was rated for), and the total heat will be less than an incandescent, so you should be safe.

    I think the real source of this confusion is that people equate watts with brightness, not power. Better packaging/labeling might help clarify this, emphasizing lumens as the measure for brightness, and mentioning wattage only for the purposes of discussing power consumption and safety.

  18. sakraft1 says:

    Wow! Makers are the greatest!

    Hi, I am Scott. I was the one who originally mailed the question in to Phillip. Thanks for posting my question right on the Make blog, Phillip!

    This is the incredible wealth of information that I was unable to find just searching around (although I had a suspicion that heat was the issue).

    In case anyone wants to know, the lamp in question is an ikea FAS clamp light. It has a metal shade. I planned to use the lamp as a reading light and possibly also to light a homemade animation stand (merely a hobby). This means that the bulb will likely be upside down (which according to the information here will shorten the life of the bulb). As for the mercury issue, it is my understanding that you can bring CFLs to be disposed of (recycled?) properly, but I think this is something that needs to be driven home to anyone using them.

    Thanks to everyone that posted!

    BTW, I did get a reply from GE while I was at work today. Their reply was also informative. Here it is:

    Thank you for visiting our GE Lighting website. I will be happy to assist
    you today. Yes, it would be fine to use the 12 watt CFL in a fixture rated
    for 40 watts. The fixture is concerned with the actual electrical usage
    (26W, for example) and not the equivalent light output (100W) that the
    lamp emits. As long as the actual electrical usage is lower than that of
    the maximum wattage allowed in the fixture, it will be fine to use the CFL
    in your fixture, as long as the other conditions listed below are met.

    There are a few things to note about CFLs that can affect their operation
    and life span:

    1) They should not be used on dimmers unless the specific bulb is noted
    on the package as a “dimming CFL”.

    2) They should not be used on electronic timers. Manual timers (the dial-
    types that use push-in clips or tabs to set the timer) are “mechanical”
    and only serve to turn the circuit on or off.

    3) They should not be used on photocell devices or fixtures (dusk-to-dawn
    or motion sensing).

    4) While they can be used in enclosed OR recessed fixtures, they should
    NOT be used in fixtures that are BOTH enclosed AND recessed.

    5) If a CFL is used outdoors, you MUST be make sure it is approved for
    outdoor use, and verify the lowest operating temperature for the area
    where the product is being used. If the lamp or package does not state it
    can be used outdoors, then it is not approved for outdoor use, even in an
    enclosed fixture.

    6) Compact fluorescent light bulbs work best if they are left on for over
    15 minutes each time they are turned on. Warm-up will probably not be
    noticeable from a user stand point, but the lamp needs to warm-up in order
    to reach the point of most efficient operation. Frequently switching them
    on and off will shorten the life of the product. If the life of the lamp
    is shortened significantly, you will not reap the financial benefits
    (includes energy and life of lamp), that are common to CFL lamps. Thus,
    applications such as a closet, pantry, bathroom, laundry room, etc., are
    not optimal. Incandescent and halogen lamps are still most efficient for
    these environments.

    7) While we offer one CFL for ceiling fans, applications where there is
    vibration present (such as a ceiling fan or garage door opener) can damage
    the electronics in the ballasts of all other CFLs. The ceiling fan CFL
    should not be used on a garage door opener, which offers much greater
    vibration than a ceiling fan.

    I hope thisinformation is helpful. Please let us know if you have any
    further questions. Have a nice day, Mr. Kraft!

    Best Regards,
    GE Internet Response Team

  19. Gary says:

    can you put a 25 watt halogen bulb in place of a 25 watt regular bulb that has a plastic NOT ceramic socket. Would this be safe and adviseable?

  20. Anonymous says:

    I just had a 13 watt bulb catch on fire in a lamp for 60 watt or lower bulbs. The bulb sockets are horizontal. The is no message on the cfl about being used upright only. It melted right where the glass goes into the ballast.

    The person who said if the bulb doesn’t say it can be used in a non upright position it souldn’t be used in this lamp seems to be correct. I will look for cfls with the correct label for operations.

    Thank you

  21. semadmin2013 says:

    What ’s the advantages of LED Bulbs Lights? LED Bulb Lights not only can reduced energy use(This LED method of producing light loses far less energy to heat than do other lighting technologies), but also they have long service life(You could go 20 years without having to change an LED light bulb).