Fluorescent Light Bulbs – Five Commonly Overlooked Facts About Fluorescent Light Bulbs

Fluorescent light bulbs have been mentioned in many articles on BreviousLighting.com. My intention here is to move a step further – you are probably already aware of many advantages and some disadvantages of fluorescent lights (if you aren’t, you should read the article about fluorescent lights), but you may not know some of the other things mentioned in this article.

After you are done reading, you will know how fluorescent light bulbs work, you will know about the different shapes of fluorescent light bulbs, you will know the difference between regular and compact fluorescent bulbs, and you will also discover whether it’s possible to use fluorescent bulbs outside.

1.) How fluorescent light bulbs work

Even though I’ve already described how fluorescent bulbs work in the article dedicated to fluorescent lights, I’m going to quickly repeat it here because I want this article to contain all the necessary information about fluorescent bulbs. So, here goes …

In fluorescent light bulbs, the light is produced when electrons that are excited return to their normal level. Electrons get excited because they bump into the mercury atoms in the bulb, and when they move back from an excited to a non-excited (normal) state, they produce ultraviolet photons. When these ultraviolet photons hit the atoms of phosphor in the bulb, the visible light is made. Of course, this is a simplified version of what happens, but I hope it’s a good enough description for you to understand the basic idea of how fluorescent bulbs work. It also shows why mercury is needed in fluorescent light bulbs.

From this you can see some (but not all) of the reasons for the “death” of a fluorescent bulb. Fluorescent bulbs stop working due to loss of mercury (mercury is slowly absorbed into the glass and phosphor, where it can’t do its job anymore), when phosphor drops off in efficiency (causing the light to become dim and inefficient), or when there are problems with the ballast electronics.

2.) Different shapes of fluorescent light bulbs

Since the invention of fluorescent bulbs, they have been produced in various shapes and sizes. It’s impossible to list all of them, but here are some of the more common ones:

–    Medium bi-pin (tubular bulb)
–    Single pin (tubular bulb)
–    Quad tube compact fluorescent bulb (CFL)
–    Twin tube compact fluorescent bulb (CFL)
–    Circline fluorescent bulb
–    U-shaped bulb
–    Two-dimensional compact fluorescent


Picture 1: Fluorescent U-shaped bulb (source: amazon.com)

3.) How are compact fluorescent light bulbs different from normal ones?

You have probably already heard about compact fluorescent light bulbs (CFLs), but you may not know exactly what they are. Here is a simple explanation: Compact fluorescent lights are fluorescent light bulbs made to fit standard household light sockets (the same ones that were used for incandescent bulbs in the past). So, simply said, CFLs can be used instead of incandescent bulbs without changing light fixtures.

There is another difference between regular fluorescent lights and CFLs that may not be so important to the end user, but I will mention it anyway: Compact fluorescent lights have the light ballast integrated into the light bulb. Regular fluorescent light bulbs don’t have the ballast installed, because it’s a part of the fluorescent light fixture.

As you can see, most people use CFLs and not regular fluorescent bulbs, mostly because CFLs can be used in light fixtures that had incandescent bulbs installed previously.

4.) CFLs can be used outside

Many people wonder if compact fluorescent lights are more sensitive than regular fluorescent lights or incandescent lights. Most CFLs can be used outside if they are installed in a closed fixture, but you should always check the bulb’s instructions to see if it’s suitable for the way you will use it before you buy it.

5.) How to properly dispose of fluorescent light bulbs and what to do if they break

Because fluorescent bulbs contain mercury, they need to be disposed of separately, which means that you can’t just throw them in the trash bin with other waste. There are many available recycling options and the EPA (US Environmental Protection Agency) is working with CFL producers to increase the number of locations where you can recycle CFLs. For now, you can recycle CFLs at waste collection agencies, at local retailers, and at mail-back services. You can visit earth911.com to find your nearest recycling center.

But if a bulb breaks in your home, you don’t have time to search for instructions about what to do – you will need to react quickly. Here are some instructions provided by the EPA:

–    You should air out the room before you start cleaning up the broken glass (people should leave the room as soon as possible).
–    Scoop up glass fragments and powder using stiff paper and place them in a glass jar with a metal lid or in a sealed plastic bag.
–    If the bulb broke on a hard surface, wipe the area with paper towels and put them in the jar or plastic bag  – do not use a vacuum cleaner to clean up the broken bulb.
–    If the bulb broke on a carpet or rug, you should pick up the larger pieces of glass by hand and use duct tape or something similar to collect smaller pieces (you should put them in the jar or plastic bag like you would do if cleaning a broken bulb off a hard surface).

The clean-up materials should be disposed of properly – in some states it’s allowable to put them in an outside trash container, while in other states you should take them to a local recycling center. Make sure you know your obligations in case something happens. You should also read full instructions for dealing with a broken CFL on the EPA website (they have information on what to do with clothes that were in direct contact with mercury, and so on).


We’ve covered quite a lot – you now know how fluorescent bulbs work, you know of some different shapes of fluorescent bulbs, you know the difference between regular and compact fluorescent bulbs, and you also know how fluorescent bulbs can be used outside. Because fluorescent light bulbs can be dangerous, you also know how to dispose of them properly, and you know what to do if a fluorescent light bulb breaks.

I must warn you that there are many other aspects of fluorescent light bulbs that I still haven’t mentioned. Hopefully, I’ll describe them in one of my next articles. I hope you enjoyed reading this one.

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