June 02, 13
A T-5 Lighting Primer
“T-5” refers to a fluorescent lamp, tube or bulb with a diameter of 5/8 inches (its metric equivalent is T-16, 15.875 mm) that is typically manufactured for very small fixtures. First introduced around 1950, it originally was available in 4 – 13 wattages. More recently high efficiency (HE) ranges of 14 – 35 watts and high output (HO) ranges of 24 – 80 watts have appeared. Compared with T-12 or T-8 lamps, T-5 tubes can fit into smaller spaces, meaning more tubes for more light. Since it is a smaller light source, the direction of beam emission can be more accurately controlled by utilizing reflectors and lenses in the luminaire or fixture. T-5 fluorescent lamps boast a highly efficient lumens/watt ratio since its peak light output occurs at 95 degrees F (35 degrees C) ambient air temperature. The voltage is regulated by three types of electronic ballasts: instant start, rapid start and programmed start and can be used with a dimming ballast to control lamp current.
Businesses seeking greater lamp efficacy and cost savings often opt for T-5 lighting technology. Unfortunately, changing from T-8 to T-5 lighting involves more than swapping out bulbs. The change involves either installing new luminaires or a retrofit conversion, as T-5 lamps are incompatible with T-8 luminaires. T-5 lamps are 40% smaller than T-8 lamps and have a smaller bi-pin base. Conversion kits are available which convert existing T-8 fittings to utilize energy efficient, high frequency ballasts while accommodating the smaller diameter T-5 lamp. The magnetic ballast remains in place but is bypassed as a conductor. The new high-frequency electronic ballast draws but 2 watts as opposed to the 6 – 10 watts of the old magnetic ballast, thereby increasing efficiency. There are two choices between conversion kits. One is known as a “lamp-end” type, which include a replacement starter and two individual components fitting over each end of the T-5 lamp. The lamp is then slotted into the existing T-8 fitting. The other is a “baton” type, which is a one piece kit which slots into the existing T-8 fitting and into which the T-5 lamp is placed.
In this “green” age of sustainability and energy efficiency awareness, there are many reasons to use the T-5 lamp for lighting. They can cut energy use by two thirds over fluorescent bulbs used with magnetic ballast and last 25% longer than a T-8 bulb. They save money over time because during their longer lifespan they produce more light with less wattage. Used in conjunction with motion sensors, even greater potential cost savings can be realized. Over its lifetime of use it retains 90 – 95% of its initial lumens. It is environmentally “friendlier” than other fluorescent bulbs because of its low mercury content. Its surface luminance is higher than T-8 bulbs – which can lead to glare issues, particularly in HO bulbs – but these concerns can be addressed by use of louvers or diffusers. Because of these advantages T-5 fluorescent lighting has become a popular choice for a wide variety of applications.