Specifications of High Bay T8 Fluorescent Lighting

Ballasts

• Electricity excites mercury vapor in a lamp that causes a vaporous phosphor, ordinarily argon, xenon, kyrpton neon or xenon to produce light. Fluorescent lights require ballasts that ignite the lamp with a high voltage pulse of electricity. The three types of ballasts are preheat, rapid start and instant start. High bay T8 lamps are most commonly ignited by rapid start or instant start ballasts.

Length

• T8 lamps are mostly commonly 36 or 48 inches long. A solid state ballast is available on newer instant start 32 watt T8 lamps that are 48 inches long.

Connection

• Most fluorescent lights in homes connect to the sockets with two pins. Long T8 instant-start lamps up to 8 feet may connect with a single pin. These single pin T8 lamps are commonly used in high bay lighting.

Performance

• The Consortium for Energy Efficiency says a 32-watt high performance T8 lamp that is 48 inches long should have at least 88 mean lumens per watt for programmed rapid start ballasts and 90 MLPW for instant start ballasts. A lamp’s MLPW is how many lumen of light it yields for the number of watts required to run it. A lumen measures visible light. Generally speaking, the more watts of electricity needed to operate a lamp, the more lumens of light it will yield. A T8 lamp should have a color rendition index of 80 on a scale of one to 100. The CRI measures the ability of light to reproduce colors compared to a natural light source. The lamp should initially yield 3,100 lumens, and at an average of three hours per start it should last 24,000 hours per start producing 2,900 mean lumens.

Quality of Light

• There are no standard names for the quality of light produced by different combinations of phosphors in fluorescent lamps, but white lights are generally called warm, cool or daylight. “Warm” or “soft” shades of white are generally marketed for home use. Grocery stores commonly use cool white bay lamps for all areas except for bakery, vegetables and meats where they use warm whites to make their products look more attractive (See Reference 1).