When Should You Not Use An Energy-Saving CFL Bulb?

When Should You Not Use An Energy-Saving CFL Bulb?

A major part of how I cut my electric bill was swapping out old incandescent light bulbs to CFLs, which use less energy and last longer. On paper, the CFLs are better in every way, but apparently, Unpluggd says there are some times when you shouldn’t use them.

Apparently, a major concern for CFLs is temperature. The ambient temperature shouldn’t exceed 50C, which shouldn’t be a concern usually, except some lamp enclosures and fixtures don’t have adequate ventilation.


This image gives you a quick overview of what you should look out for when you swap over your bulbs. For ceiling fixtures, you need a small gap between the mount and the glass. For lamps, look for vents near the base of the mount, and avoid anything that totally encloses the bulb.

In truth though, higher temperatures aren’t going to break your CFLs immediately — they’re just going to last less long than they would in optimal conditions. Even if you only get, say, four years instead of eight, the energy savings will be worth it when you compare them to incandescents.

When You Shouldn’t Use CFL Bulbs [Unpluggd]


  • I’ve had issues with vented holders that reflect back to the lamp as well. Phosphors like reabsorbing their own radiant energy, the rest of it not so much.

    • Yes I was just thinking this also while reading the full article. Surely they have thought about this Safety Rating thing in relation to large scale applications.

    • Technically yes, but realistically no. There are still many applications that there is no substitute for an incandescent. Think ovens, microwaves, other specialist applications.

  • I thought cfl’s didn’t create heat like incandescants. Heat is energy, so are the CFLs using the same energy as an incandescant? I have some CFLs that run hotter than the 60w incandescants they replaced. I feel we’re not getting the full story about these bulbs. And also, how much mercury are we spreading into the environment? “A little bit” is too much.

    • I don’t think it’s so much about the amount of heat put out by each type of bulb, I think it’s more that CFL bulbs are far more heat sensitive than conventional bulbs (pop open the plastic base on a CFL, and you’ll find circuitry – something that isn’t present in a incandescent bulb)

  • I’ve been using a CFL bulb in a “non suitable” lamp (right image) for 2 years with no issues. The main issue with cfl is that they’re significantly longer that the current housing, so they poke out.

    • Have you felt how hot LEDs can get? Most LEDs for domestic lighting have massive heat sinks attached. Without the heatsinks they would melt in minutes.

      • We recently purchased a couple of LED cree bayonet lights from ebay.
        Firstly, they don’t get hot at all. After running 24/7 for the last couple of weeks, the casing was still cold. Not even warm.
        Secondly, the light emitted appears to be better than the florescent glow that comes from cfl globes. It throws a much more precise shadow on the wall, rather than a blurred blob. This is important, because it makes it feel closer to sunlight, and less likely to flicker.

        A good example of LED lights is to walk through the TV display section of a retailer. You can physically feel the heat from every TV sold, except the LED ones.

        I don’t know what LED lights you’ve been near, but I assume you’re talking of the old standard which still don’t even get as hot as the old incandescent monsters, or the CFL globe housings.

        We’re about to move house, and that’s going to be fitted out with LED globes, and LED uncounter light strips. Yes, we’re that impressed. Most LED lights have dropped in price and can be sourced online for about the same or less costing as traditional lighting.

    • The idea that switching them on/off for short durations was somehow bad was debunked, possibly my Mythbusters, some time ago.

      As for complaints about dim CFLs and one’s that take a while to reach full brightness, I’ve found that cheap ones seem to have a lot more problems than name brands.

      Personally I prefer a CFL light to an incandescent, but I’m probably a minority in that judging from comments!

      (oh and there ARE CFL replacements for your outside lights too!)

  • My main problem with CFL is that they get dim over time. In my experience they will only produce the advertised equivalent wattage (say, 40 or 60w) for a couple of months. Then they decrease noticeably.

    As the CFLs I have go out I will be replacing them with higher rated ones to see if, when they decrease intensity, they end up where I want them.

    I also have a couple of dimmers in the house that I think won’t work with CFLs.

  • i moved into an apartment where they used cfl downlights throughout the kitchen and bathroom. it takes 2-3mins to have full power. can you imagine standing in the bathroom in the middle of the night waiting for the light to warm so u can see what your doing?? i changed all of them to a low wattage halogens until LEDs become cheaper.

  • The claim that CFL’s don’t generate much heat is patently false. Ask anyone who’s tried to change a CFL after it has been on for a while, just how hot those things get.

    I have 2 CFL’s in a pole lamp next to my computer, and beneath the lamp is a clock that also tells the temperature. Both CFL bulbs point upward, toward the ceiling.

    When I turn on the lamp to begin working, even on very cold days, the temperature rises very quickly. It has risen as much as 8-10 degrees Fahrenheit in just 2-3 hours’ time, which can become very uncomfortable. Incandescent bulbs are slightly hotter, but that doesn’t make the claims about CFL’s any less misleading. I’ve spoken to electricians who say they use CFL’s, and have seen no significant reduction in their energy bills.

    Also, I’ve never had a CFL last more than 2 years, even when used according to directions. One of them lasted a month, another only two weeks.

    IMHO, it’s all a scam to make people buy unreasonably expensive bulbs in the false hope of saving money and helping the environment. However, between the lack of energy savings and the fact that CFL’s are hazardous and must be disposed of properly, these bulbs are just adding to the pollution problem.

  • I run a large lighting store, with just under 1000 of our display lights using CFLS. Another 1000 or so use halogens or other globes. I think that gives me some good insight.

    Melanie, I disagree with a number of your points. Yes, they do get hot – but nowhere near as hot as an incandescent. I appreciate they can get uncomfortably hot to handle (depending on wattage) but try handling a 75-100w incandescent after it has been running for a while.

    Several years ago, we decided to update our displays and changed 875 products to CFL in one go – we carefully tracked the results and our power bill dropped 20-25% every month thereafter. Two years ago we moved the showroom and the majority of the CFLs installed at the time are still going strong (10 hours a day, 7 days a week, 360 days a year). The hundreds of incandescents (or halogens) still in use need to be monotonously changed regularly. The difference is obvious, because I need to allocate labour to this task every week over and over – the CFLs almost never need changing.

    Your electrician friends may not be seeing the difference because lighting is typically only 17% of your average household load – heating, hot water and air-conditioning is a huge component. They just haven’t tracked it accurately with increasing prices eating up the savings.

    Finally, the quality really does make a difference. Are you using supermarket globes? Even the “name brand” ones in the supermarket (say, Philips or Osram) are often the budget products from those brands. My favourites are GE (yes, I’m biased, but I’ve used thousands and thousands of them).

    Buy good ones (you may need to shop around and experiment) and choose the right colour temperature and wattage for your taste and needs and the results will be worthwile.

  • Oh, and for those that really don’t want CFLs, you should be able to find “eco halogens” if you look around, which are essentially direct replacements for incandescents.

  • The halogen globes are expensive. I’ve had at least 10 blow well below the rated hours. The “30%” power saving hardly out weights the cost.

    If you really want to keep track of how long lights last, write the date on the base when they are installed and again when they are changed.

  • This is only one side of the subject. The main question is how can we remain healthy using “green” lights? To achieve this is similar to make a space travel using an old train. Because few consumers on this planet are aware of the (many) dark faces of the “green” lights. Forget the unconstitutional ban in USA EU and many other countries and remember that the bottom line is the cruel irresponsibility of the governments in any country on the Earth in not informing consumers on the countless dangers in using “green” bulbs.

    1. Mercury is a BIG issue but not the most important.
    2. The emission of radiation that probably causes countless sicknesses – maybe cancer – is not the big issue.
    3. The fact that several carcinogenic chemicals and toxins were released from their plastic parts when the “environmentally-friendly” compact fluorescent lamps (CFLs) were switched on, including phenol, naphthalene and styrene, is not the main problem.
    4. Forget the geopolitical game on rare earth metals (money and power). China is the champion on it.
    5. Forget the UV radiation, skin problems and probably cancer. This is not the main problem.
    6. The most important factor, that has NOT been understood, is that the mandatory change of bulbs entails a change in the quality of lighting. And this is OUR REAL LIFE. What is certain is that a drastic change of myriads of active electro-biochemical processes in the bodies of all people will be effected, with unknown consequences. It is extremely well-documented scientific knowledge that any kind of artificial light often and profoundly affects any living being adversely.
    This is the one and the major disadvantage of CFLs due to the radiation 400-500 nm they emit, known as blue light. This is an extremely dangerous radiation, which cause cancer and suppresses melatonin secretion, giving “craze” signals to pineal gland with countless consequent effects on both the ill and the healthy.
    The frequencies in the range of blue light (and UV radiation) are increasingly a source of concern due to their adverse health effects. Even the SCENIHR, namely the Scientific Committee of the EU, which verified the issue, almost cynically agrees with this, talking about adverse effects on the health of 25,000 people. Nevertheless, citizen unions argue that up to 70,000,000 people will be affected! In reality due to blue light everybody will be negative affected.
    Finally there is an unbelievable fact. The European Commission asked – again – for the second time (2008 and 2010) the SCENIHR “to explore and report (30.11.2011…?) scientific evidence on potential health impacts on the general public”.

    • mmm, delicious copypasta filled with technobabble. (also, “radiation” is a term with many meanings, visible light is a type of radiation, it is ionizing radiation that causes cancer)

      BTW, the mercury in a CFL is about the same as you would get by eating a reasonable size serving of tuna.


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