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Posted by Doug Root on 27th May 2020

A Primer on Fluorescent Light

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Fluorescent lighting is one of those types of lighting that you’ve definitely come across, and many times over, in your life. It is one of the most common types of lighting in the world, if not the most common, with over a billion fluorescent lamps in use in the United States alone.

Fluorescent lighting is far and away the go to choice for lighting up large spaces, whether they be commercial, industrial, or residential, and certain types of fluorescent lighting are even popular on smaller scales. For the most part, we’ve all seen our share of fluorescent lights in the forms of tube lights that are in ubiquitous use throughout offices, retail operations, schools, and other places of public gathering.

Solutions in fluorescent light are not without their drawbacks (which we will investigate below) but they are widely popular for many reasons, with the most common reasons being their cost friendliness, relative energy efficiency, and relatively high levels of luminosity. Compared to certain alternatives like incandescent bulbs and halogen lamps, they are much more energy efficient, and, while they are not nearly as efficient as LEDs, they are typically much more affordable.

What Is Fluorescence?

To understand the broader question of how fluorescent light bulbs work, you need to have a basic grasp of the principle of fluorescence. Fluorescence is one process by which radiation in the form of visible light can be emitted.

For example, luminescence is the process by which light is created through the production of heat. To illustrate this point with a very rudimentary example, consider that fire is luminescent; it excites gases in the atmosphere, causing them to emit radiation on the visible spectrum. Thus, to our eyes, fire appears to give off light.

Fluorescence is a very specific type of luminescence wherein certain chemicals or compounds emit a visible form of radiation after being stimulated by another form of radiation. The process has been observed by humans for a long time, but the name which we recognize was given to the process in 1852 by George Stokes. Stokes, a physicist, named the process after the mineral fluorite (which contains the element fluorine) after observing that fluorescent materials emit visible radiation if they are excited by another form of radiation with a smaller wavelength. In short, fluorescent materials will glow with visible light when stimulated by UV light.

So, in a nutshell, when a fluorescent material (one that contains fluorine) is irradiated and stimulated by ultraviolet radiation, it emits radiation on the visible spectrum of light. So how, exactly, does a fluorescent light work?

How Do Fluorescent Light Bulbs Work?

The process that occurs with a fluorescent light is actually somewhat more complex than one might expect. Every fluorescent bulb is, to put it simply, a sealed glass chamber that contains a mixture of gases and other chemicals. The actuation of the bulb, as might be expected, requires the input of electricity.

When you switch on the light, electricity flows through the ballast of the bulb, which is a device that regulates the flow and voltage of electricity, and in some cases, heat, in order to enable the light to emit a steady and predictable light.

Once the electricity flows through the ballast, it reaches the pins of the lamp. Through the pins, the current reaches the electrodes inside the glass tube of the lamp. Once the electrons reach the electrodes, they are free to flow across the lamp from one side to the other.

The inside of the tube is full of a mixture of inert gases, typically, xenon, argon, krypton, or neon, as well as mercury. As the electricity excites the mercury, the mercury vaporizes and interacts with the inert mixture of gases. This interaction produces ultraviolet light. The ultraviolet light is invisible to the human eye, but as explained above it is critical to initiating fluorescence and is the key to the operation of a fluorescent lamp.

The insides of the fluorescent light are coated with phosphor powder, which is a combination of several different elements and contains fluorine. This is the reason that fluorescent lights look like they are frosted on the inside. When the ultraviolet radiation contacts this powder, the powder glows, and this is manifested in the light you see emitted from a fluorescent bulb.

It’s a complex process, but not complicated to understand. In summary, the electricity that runs across the tube inside the bulb creates a reaction that emits ultraviolet light, which in turn stimulates the fluorine-containing phosphor inside the bulb, causing it to fluoresce.

Where are Fluorescent Lights Popular?

As stated, you are probably already very familiar with fluorescent lighting, even if you were previously unsure it was fluorescent lighting you were under. Due to their high measure of luminosity, they are very popular for lighting up large indoor spaces.

One of the most common places you would be liable to encounter fluorescent lighting is inside of an office building or another commercial or industrial building. The lighting used overhead very frequently takes the form of fluorescent tube lights, which are probably readily familiar to you. If you’ve ever looked up at the long, thin, bright white lights that are often set in front of those concave silver reflectors above hallways and other open areas, you were almost certainly looking at fluorescent lights. Now that you understand where they are commonly used and how they work, what makes them so popular?

Advantages of Fluorescent Lights

It’s definitely true that fluorescent lights are extremely popular in a wide range of indoor settings, and we briefly touched on some of the reasons for this earlier in this article. That being said, none of them was probed. 

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In the first place, fluorescent lighting can generally realize cost savings for the organization that implements them. Although alternatives like LEDs have their own unique benefits like longevity and low operating costs, they are typically much more expensive than fluorescent lights. So in that regard, they can even save money up-front.

It is also true that while fluorescent lights are significantly more expensive than most incandescent lights and other alternatives, they use much less energy and they also tend to last much longer. In that respect, they can potentially offer huge energy savings for the companies that implement fluorescent lights instead of other lamps. In addition, fluorescent lights also produce significantly less heat than some other lamps, namely incandescent bulbs. That helps to keep the spaces they are used in much cooler as well. Consider an office lit by fluorescent bulbs in the summer. On the one end that they will save money on energy bills by using less electricity, and on the other hand, they can even keep the air conditioning costs down.

Fluorescent bulbs also last a lot longer than many other lights. Again, a big culprit here is incandescent lighting. Many incandescent bulbs will last somewhere around 1000 hours, with some projected lifespans falling on either side of this spectrum. Most fluorescent bulbs will last 10,000 hours, and some are even rated to last as long as 50,000 hours. That is vastly longer than almost every alternative. The only alternative that routinely comes close to this lifespan (or exceeds it) are LEDs, which come with their own benefits and drawbacks.

To close, fluorescent lights draw less energy and keep spaces cooler while at the same time, lasting much longer than other forms of lighting.

Disadvantages of Fluorescent Lights

While fluorescent lights last a long time and cost less money to operate, in general, they are not without their shortcomings. These are some of the things to consider when weighing the positive effects of fluorescent light.

We touched on this briefly, but fluorescent lights tend to cost more up-front than alternatives. This has the potential to make them cost prohibitive in the first place. That being said, some studies have indicated that most fluorescent lighting will pay itself off within a year, or even shorter. That can only be conclusively proven with an extensive energy or lighting audit, but it has been posited in some situations.

There is also the fact that fluorescent lighting contains mercury by necessity, which is responsible for the reaction that emits UV light and makes fluorescent lighting possible. Since mercury must necessarily be involved in the production of these types of bulbs, there is no way to engineer it out. Also, since mercury is considered hazardous, there are very strict guidelines for the handling and disposal of fluorescent lights. That also has the potential to make disposal of these lights time consuming and possibly expensive when the lights do reach the end of their lifespan.

Then there are some minor issues associated with fluorescent lights that have largely become technologically eradicated. Fluorescent lights are the ones that make that familiar buzzing sound, but that was largely due to the use of a magnetic ballast, and since most if not all new fluorescent lights use an electronic ballast, the buzzing is a thing of the past.

Fluorescent lights are also known for needing a warm up period before reading their full brightness, as well as for flickering, but again, due to advances in technology, these problems are rare today. Most new fluorescent bulbs will light up and reach their full potential very quickly.

Common Types of Fluorescent Lights

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Linear Fluorescent Tube

This is arguably the most commonly encountered type of fluorescent light and is also probably the most recognizable. Linear fluorescent tubes are the long fluorescent tube lights that you commonly see in commercial and industrial settings, usually recessed into the ceiling. They offer most of the benefits that we have investigated so far, but they do have a slightly longer warm up period than some other lights. As we mentioned, advances in technology have reduced the warm up time and most of these lights can still reach their full brightness in under 30 seconds. In addition, since they are usually only switched on or off once per day (or left on most of the time) this isn’t an issue.

Fluorescent Bent Tube

Fluorescent bent tube lights are effectively the same as linear fluorescent lights, except they take the form of a bent tube, usually a U shape. Probably the most common form of this light is the T8 fluorescent light, which has more or less the same benefits and drawbacks as the linear fluorescent tubes described above.

Fluorescent Circline

If you’re not familiar with lighting you may never have seen circular fluorescent, or circline lamps, before. They are, as the name might suggest, circular fluorescent lamps that can be somewhat difficult to replace. Even so, like other fluorescent lights, they are an effective source of diffuse light, although it is important to note that some fixtures have manufacturer specific requirements.

CFL (Compact Fluorescent Lamp)

There is a chance that these are the most recognizable fluorescent lamps to you since they are the most commonly used type of fluorescent light within most residences and private homes. CFL bulbs, or compact fluorescent lamps, were designed to serve as residential alternatives to incandescent bulbs, as they draw less power than incandescent bulbs and will last much longer while providing the same or even better luminosity. Generally speaking, these are the lightbulbs that, though they superficially appear like incandescent bulbs, have a corkscrew shaped glass tube.

This is only a brief introduction to fluorescent light; more could be said of their technological operation, then ballast they require, or even on the specific types of bulbs. There is a lot of information to absorb here, and we understand that. If you’d like some more specific information on fluorescent bulbs or you need some help finding the right fluorescent bulbs for specific fixtures, you can always call our team at 1-888-988-2852. Our team of professionals has years of experience with many different types of lighting fixtures including fluorescent lamps, and we’re ready to help you with any questions you might have. Give us a call today and put our experience to work for you.