Fluorescent & CFL Labeling

The fluorescent tube is essentially a low pressure mercury discharge lamp. At either end of the tube is an electrode coil, also known as the cathode, whose purpose is to inject a flow of electrons into the discharge space. On account of its high operating temperature it is made from coiled tungsten wire, and is coated with various refractory oxides which increase its electron-emission efficiency. During life the electrode disintegrates and leads to blackening of the tube ends. To minimise the severity of blackening it is surrounded by a metallic shield. This shield also serves to reduce the visible 100Hz flicker which appears in the vicinity of the electrodes when operated at ordinary mains frequencies. The whole electrode assembly is mounted onto a glass stem assembly, the rim of which is fused to the end of the discharge tube to produce a sealed vessel. Via a narrow glass tube which pierces the stem, the lamp is dosed with a small quantity of mercury and filled to low pressure with an inert gas, typically argon or argon mixed with neon, krypton or xenon. In combination with the tube length and diameter, the choice of gas filling determines the lamp's electrical properties. A phosphor coating is applied to the internal surface and a metal cap at either end provides the electrical and mechanical connection with the luminaire. The outer surface of the glass is often coated with an invisible silicone wax which breaks up films of moisture on lamps employed in humid environments. Although invisible, this feature is of paramount importance in ensuring reliable starting.

Linear Fluorescent

During the 1940s several nations and manufacturers introduced comprehensive systems of nomenclature to identify the many different kinds of fluorescent lamps which had become available. In the United States, the system of nomenclature used is: wait for it...the American system! 

As an example, we'll use the following designation for our fluorescent light bulb F32T8/841/ECO

F- The first item in the notation denotes the shape of the light bulb. Other modifiers include FC for a circular, FU for U-Bend and G for Germicidal.

32- In this case this denotes the wattage of the light bulb. This number can also designate the length of the bulb.

T8- Indicates the size or diameter of the lamp. T denotes a tubular construction and the 8 is the number of eighth inches measured across the diameter or 1". Other modifiers include TD for dented and T-XX-J (T8J in this case) for jacketed.

841- 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.

You may see another modifier instead of three numbers in label nomenclature which has one to three letters. WW for Warm White, CW for Cool White, N for Natural, D for Daylight, WWX for Warm White DX, CWX for Cool White DX or BLB for Blacklight.

ECO- 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.

Non-Linear Fluorescent

For labeling examples of non-linear fluorescent light bulbs, including circular, U-tubes and W-shaped, go to this page.

Compact Fluorescent

During the energy crisis of the 1970s, the first real efforts were initiated to begin developing a more efficient light source which could replace the traditional incandescent lamp. It was recognised that the relatively small improvements that had taken place in incandescent lamps during the previous four decades were not enough, and there was potential for replacing it with one of the other newer lamp technologies.

The main focus in Europe was on miniaturising fluorescent lamps and equipping them with compact integrated ballasts, while the Americans initially focussed on miniature self-ballasted metal halide sources. Additional efforts were directed by both continents towards miniaturised electrodeless induction lamps.

Ultimately it was the compact fluorescent approach that won, thanks to the timely development of a new series of phosphors that could endure the higher thermal loadings in small lamps, and the parallel development of miniaturised ballasts. The advantages of the resulting lamps were so significant that they also led to the introduction of the large family of non-ballasted compact fluorescent lamps, intended directly for use in new luminaires having remote control gear.

The choices CFL lamps offer for incandescent replacement lamps come in almost any form as you can see by the examples below. Use the table below as a guide for CFL replacements that are equivalent to the incandescent you are replacing.