T5 Lighting Fixtures

Many modern ceiling light options are available through advances in high-performance lighting technology. Smaller lamps are being used to meet the lighting industry’s efficiency requirements. The T12 lamp started this trend of constantly decreasing the size of new fluorescent products.

The newest series of Fluorescent High Bay Lights are the T5 lamps, which are either standard or high-output. Originally developed in Europe, the T5 lamp came to North America in 1996. The T5 luminaries did not take off quickly in the market, mostly because of its price difference from the T8 systems. Then the T5 HO lamp, which is the high-output version of Fluorescent High Bay Lights, was introduced to America in 1998.

T5 lamps come in sizes of 2 to 5 feet in length. The 4 ft T5 lamp is actually 45.8 in. long. The T5 lamp has a generally brighter output compared to the T8 lamp system. The T5 is offered in temperatures of 3,000°K, 3,500°K, and 4,100°K. The T5 lamps have a color-rendering index (CRI) of 85 or 82, compared to the T8 with a CRI of 75 or 85.

The T5 and T5 HO are the same size, but have different outputs. The T5 has an output of 2,900 lumens, which is close to the T8 output, while the T5 HO puts out up to 5,000 lumens, almost twice the output. With the T5 HO lamps, designers can use fewer lamps on projects, and saving money because of less maintenance. Because of a .625 inch bulb diameter, and a mini bi-pin base, the T5 lamp is useful in lower profile areas. The high output and thinness of the lamps makes them good for indirect and shallower lighting.

Many fixture designs have been made for the T5 lamp, altering its dimensions and helping to distribute the light output more effectively. With T8 or T12 fixtures, an effective distribution is made only from suspending the lights a minimum of 2 feet from the ceiling. This would be too low for many office buildings where ceilings are not high. However, using the T5 lamp, suspension from the ceiling can be as short as 15 inches, leaving plenty of headroom.

With power ratings of 24, 39, 54, and 80, the T5 HO lamp easily beats the T8 or T12 system with over double the output. Every T5 HO lamp requires its own ballast, but they are 10-15% less effective than normal T5 models. T5 HO ballasts also have many advanced features such as a dimming function, or operating multiple F54 lamps.

The T5 system also provides its peak output at 35°C, next to the T8’s or T12’s peak output at 25°C. This makes the T5 system a better choice in an output over temperature ratio, and a better choice to use for effective lighting in small, and low air circulation spaces.

Because of the lamp’s small size and high power, temperature can rise as the lamp dies because of less cathode emission material. This rise in temperature can cause the bulb wall to crack. The T5 ballasts have a built in end-of-life circuitry, which stops the bulb from cracking by shutting off the lamp when there is a rise in voltage.

The T5 lamp also has a lower mercury content because of a coating that stops absorption of mercury. Only 3 mg of mercury are needed for the lamp, instead of the 15 mg that would be needed without the coating. The lower mercury absorption also keeps the lights output as strong as its initial output throughout its life.

The T5 and T5 HO lamps are increasingly used in offices and industrial areas. The T5 HO system is now available to be used in any area with a ceiling higher than 15 ft, including gymnasiums and warehouses. The T5 offers over 50% more energy saving than a 400W metal halide system.