T5 fluorescent fixtures (shown above right) offer as much as a 65% reduction in energy use compared to older T8s and about a 50% energy reduction compared to high-pressure sodium lights (shown above).
High-intensity discharge light sources, such as metal halide and high-pressure sodium lamps, have enjoyed a preferred use in high-bay buildings like farm shops. But improvements in fluorescent lamps provide a highly viable option. Today's T5 fluorescent tubes offer myriad advantages, including cheaper operation, instant startup, reduced glare, better light quality, and longer life.
“We choose to go with six-bulb T5 lights when we built our shop based on the recommendations of our electrician,” says Tom Crave of Crave Brothers Dairy in Waterloo, Wisconsin. “He recommended T5s because they're very efficient and provide great working light.”
You can readily tell the difference between T5 lights and older fluorescent versions such as T8s. Size-wise, T5s are smaller by 40% in diameter (⅝ inch) compared to T8 (1 inch) tubes. This allows T5 tubes to fit into smaller spaces. They also give more accurate control of beam direction by means of optics.
Silent and long-lived
T5 fluorescents also employ electronic ballasts, which are not only smaller but also quieter. Three types of electronic ballasts are available for a T5 fixture: instant start, rapid start, and programmed start.
Where T5s excel is in putting out cheap light. They deliver a higher lumens-per-watt efficiency than T8 bulbs of about the same wattage. Their peak light output occurs at 95°F. compared to 77°F. for T8s, which makes them ideal for hot locations.
For farmers who detest changing bulbs, the T5 is a godsend. They generally last 20,000 hours compared to 15,000 hours for T8 lamps.
Don't lament if your shop is adorned with T8 lights – you can convert them. The magnetic ballast in the old fixture remains in place, but it is bypassed with a new T5 ballast. This new high-frequency ballast draws only 2 watts, rather than the 6 to 10 watts of the old ballast.
The T5 advantage is almost as pronounced when compared to high-pressure sodium (HPS) fixtures. Costwise, they operate more cheaply. A four-lamp T5 draws around 235 watts compared to 455 watts for a single-bulb HPS.
Light output of a T5 equals that of an HPS. Its quality, in terms of color, is superior. For example, a T5 has a color rendering index (CRI) rating of approximately .85, and that compares very favorably to actual sunlight. An HPS gets a rating of 65 CRI. T5 light coverage is more diffused, which minimizes floor hotspots.
Other T5 advantages over HPS include instant-on operation, lower operating heat, quieter operation, and a much longer life.