A Compact Guide to Compact Fluorescent Lighting: The Twisted CFL

Think of a lightbulb. Ok, got it? I’d imagine the picture that came to mind is small and bulbous. This is the original incandescent A19 that most people are very familiar with.

Now, imagine a fluorescent tube; one of those long, white, skinny bulbs that flicker for a minute when you flip the switch to turn it on, the fixture quietly humming as power surges through the ballast, bringing life to the gasses filling the glass cylinder.

Now that we have both images in mind, merge them together so that the fluorescent tube fits inside the incandescent housing. Voila! You have created a Spiral (we like to call them Twist) Compact Fluorescent light bulb, succinctly dubbed the CFL.

Twisted CFL Shapes

Compact Fluorescent Lamps (CFLs) are basically just miniature versions of the standard tubes and are available in a variety of shapes and sizes. Designed to be more practical than their incandescent counterparts, CFLs have been a long-standing contender in the fight to improve energy efficiency and bulb life expectancy.  What consumers have appreciated most, however, is that CFL bulbs are simple to install and are self-ballasted — meaning they can be used in place of a standard bulb without needing to rewire your fixture to make them work.

These bulbs are also manufactured with or without a housing. Most people are familiar with the naked CFL, which shows off its curves in all its twisted glory! Others are encased in a plastic frosted covering to make them appear more like a traditional incandescent A-shape, torpedo or flame tip chandelier, or globe light bulb. While both options are great, keep in mind that the covered CFLs tend to have fewer lumens (are less bright) because the light must fight through the frosted plastic to illuminate anything of importance.

Twist CFL bulbs come in several sizes, and like all other light bulbs are identified by a given code that relays the type of bulb technology along with the diameter of the tube. For CFL bulbs, these codes always start with a “T” and are followed by a number to indicate the size of the tube, measured in eighths of an inch.

Perhaps the most important factor to consider when selecting a CFL is the overall size (height and width) of the bulb itself, as this can impact whether it will work properly in the fixture as intended. CFL Twist bulbs are as small as 2 inches and as large as 15 inches, so this can be a pretty crucial piece of information to have before you make your final choice.

To determine which size CFL is best for you, measure the space the bulb will be used in or base it off of the bulb being replaced. Wattage equivalence scales are a good indicator when figuring out a replacement CFL for your incandescent lights too since Twist CFLs are a frequent stand-in for the older technology. For example, a 13W CFL is generally equal to a 60W incandescent, and both bulbs will have roughly the same dimensions overall.

Base Types and Sizes

Another important factor in selecting a CFL light bulb to replace your incandescent is the base size and type. Like traditional light bulbs, CFLs feature standard base sizes:

CandelabraE12
Medium ScrewE26
MogulE29
GU24Twist-and-Lock

There are a few other base types that are found with CFL bulbs, but these are the most common ones in use. Keep in mind that as CFL technology is replaced with even more efficient LEDs, expect to see fewer options available on the market for CFLs, in general.

Why use a Spiral CFL light bulb at all?

As mentioned earlier, Twist CFL bulbs are self-ballasted. This allows them to operate without needing to be connected to an external ballast to regulate the flow of energy into the lamp. As such, a wide range of spiral CFLs has been used to replace traditional bulbs in a variety of applications. Mini-twist bulbs generally replace standard incandescent in table lamps, wall sconces, chandeliers, and general-purpose locations. Larger CFLs, which usually pack a bigger punch in the brightness category, are used in track lighting, recessed cans, and other fixtures where more light is needed – usually in commercial, retail, and healthcare settings where the lights won’t be switched off frequently.

This is important to note with CFLs because regularly turning these lights on and off can negatively impact the bulb’s lifespan. As such, they are not recommended for use in bathrooms, closets, or other areas where light is only needed for a few minutes at a time.

All-in-all, Compact Fluorescent Lightbulbs have served us well since 1976. True to form however, it is a component in an ever-changing industry that strives to work better and be better, at every turn. The invention of the light bulb changed the course of history, bringing light into homes after the sun had set and allowed entire industries to blossom virtually (and literally) overnight. It is no secret that CFLs have played a keen part in this saga by reducing energy waste while performing to a standard in lighting which we have all become accustomed to. While CFL bulbs may not be around forever, we can all appreciate their contribution to shaping the lighting industry and the role they have played in our lives over the past several decades.