T8

T8 refers to a type of fluorescent lamp characterized by its diameter and form factor. The designation comes from the “T” for tubular and the number eight indicating the tube’s diameter in eighths of an inch, resulting in a standard 1.0 inch (25.4 mm) diameter tube. T8 lamps are most commonly used in commercial and institutional lighting and are available in several lengths, with 4-foot and 2-foot variants being the most common. They are designed to operate in fixtures that use a G13 bi-pin base at each end and typically work with magnetic or electronic ballasts.

In terms of performance, a typical 4-foot T8 lamp operates around 32 watts, delivering roughly 2,400 to 3,100 lumens depending on the specific model and color temperature. Color temperatures commonly offered include warm (about 3500K), neutral (around 4100K), and cool daylight options (approximately 5000K to 6500K). The lamps generally provide a Color Rendering Index in the mid-80s, though this can vary by manufacturer and model. Modern T8 installations often utilize higher-efficiency electronic ballasts, improving overall energy performance and light quality.

Retrofits and alternatives are widespread. T8s can be replaced with LED tubes designed to fit T8 fixtures. Retrofit options include ballast-compatible (Type A), ballast-bypass (Type B), and external-driver (Type C) configurations. When converting, considerations include ballast compatibility, fixture design, and electrical safety. T8 tubes contain mercury and require proper handling and disposal under local regulations.

Lifespan for fluorescent T8 lamps typically ranges from 15,000 to 30,000 hours, depending on usage and operating conditions. They remain a common choice in many lighting standards and guidelines for cost-effective, efficient illumination.