Resource Center Contact Us My Account
Home » Resources » Linear Fluorescent Nomenclature

Linear Fluorescent Nomenclature

When looking into fluorescent lighting, whether for new installations or for upgrades and renovations, many people are confused about the nomenclature, especially when confronted with common terms in the field. Let’s look at an example:


How do you read Linear Fluorescent Nomenclature?
Here is an example: F32T8/841/ECO


The first letter determines the shape of the lamp. The most common is “F” for a straight, linear fluorescent lamp. Other notation could be “FB” for a U-bend fluorescent lamp and “FC” for a circular fluorescent lamp.


The number after the shape notation is used to note either the rated nominal wattage of the lamp, or the nominal length in inches. This can vary depending on the lamp type. In our example, it’s a 32 watt lamp.


The size of the lamp. The “T” in T5, T8, and T12 simply means “tubular”. The numbers after the “T” (i.e. 5, 8, and 12) refer to different diameters of those tubes. Figuring out these sizes in inches requires just a little basic math. All these measurements are in eighths of an inch. Thus, a T12 lamp is 12/8”, or 1-1/2”. A T8 lamp is 8/8”, or 1”, and a T5 lamp is 5/8”. That’s simple enough.


These three suffix digits tell us about the quality of light output by the lamp. The first digit indicates the CRI of the light. A “7” indicates a CRI of 70 or more, while an “8” indicates a CRI of 80 or more. The last two digits denote the white color temperature. Commonly you will see “30”, “35”, “41”, “50”, or “65”, which are used to indicate color temperatures of 3000K, 3500K, 4100K, 5000K, and 6500K, respectively. In our example above, 841 means our lamp is 4100K and has a CRI of 80 or above.


After the light quality suffix, manufacturers will often have additional data about their lamp. These terms can be used to indicate a variety of different options or characteristics about the lamp. Some examples are high output (HO), very high output (VHO), rapid start (RS), instant start (IS), energy saving (ES), and many more. In our example, “ECO” is used by the manufacturer to indicate a low-mercury TCLP compliant lamp.
So that’s the basic break-down of nomenclature for linear fluorescent lamps.

Why should you care if a linear fluorescent light is a T5, T8 or T12? Each has specific qualities, as well as pros and cons. What’s more, government regulations mean that you’ll have to make some decisions about these linear fluorescents eventually.

You see, to boost energy efficiency, the U.S. Department of Energy decreed that manufacturers must stop making T12 lamps as of 2013. That’s because these are the least energy-efficient lamps of the group.

The smaller T8 lamps are more energy efficient than the T12 lamps. And the even smaller T5 lamps are much more energy efficient than even the T8 lamps.

There are tradeoffs, however, because T5 lamps can cost two or three times as much to buy as T8 lamps. Although retrofitting existing, outdated linear fluorescent lighting with newer lamps is popular because it can save money, another option is simply to install brand-new fixtures with T8 or T5 lamps.

At Take Three Lighting, we can walk you through the process and help you decide which types of linear fluorescent lamps make the most sense for you. We offer premium lamps from the top manufacturers in the field, and our experts can give you fast, trustworthy advice. Contact us today.

Get a Custom Quote for Fluorescent Tubes

Contact us today and let us assemble a custom quote for your bulk linear fluorescent tube needs.

Related Items