Comparing T5, T8 and T12 Lamps
The “T” in lamp nomenclature represents the shape of the lamp-tubular. The number following the “T” usually represents the diameter of the lamp in eighths of an inch (1 inch equals 2.5 centimeters). T5 lamps have a diameter equal to 5 times an eighth of an inch, or 5/8″. These lamps are approximately 40% smaller than T8 lamps, which are one inch in diameter, and almost 60% smaller than T12 lamps, which are 1½” in diameter.
T5 lamps are fluorescent lamps that are 16mm or 5/8″ of an inch in diameter. T5 lamps are a popular energy-efficiency measure, due to their potential to cut energy use in lighting by more than 60%.
They also have a low mercury content.
In order to determine how T5 lamps can help you save money, it’s important to discuss the physical characteristics of T5 systems compared with T8 systems and T12 systems.
T5 lamps use 45% and 12% less energy than their T12 and T8 predecessors. It provides peak light output at 35 °C (95 °F) air temperature. (By contrast, the T8 and the T12 lamps provide peak light output at a 25 °C [77 °F] ambient air temperature.) The T5 lamp has a higher lumens-per-watt efficiency than a T8 lamp of about the same wattage, in a space where there is little or no air circulation.
A fluorescent lamp’s “cold spot” is the area on the lamp where the temperature is at its lowest. This cold spot rises or falls along with the ambient temperature of the lamp. Unlike a T8 or T12 fluorescent lamp where the cold spot is in the middle, in T5 lamps it is at the end on the metallic cap, about 2 mm from the glass envelope.
T5 lamps generally last for 20,000 hours, as compared to T8 lamps, which last for 15,000 hours. These differences in dimension prevent T5 lamps from being used as replacements for T8 and T12 lamps, unless the existing luminaries are electronically converted via T5 retrofit conversion to high frequency operation so that they can accept the T5 lamps.
Saving Energy And Money With T5 Lamps