High perfomance T-8s.

By Michael Lane LC
www.lightingdesignlab.com

"Super", "Premium", "Enhanced", "High- Lumen" T8's. What are they? Who makes them? Should you use them, and most importantly what should you call them? High Performance T8's is the correct name. The basic definition is a lamp that produces 3100 or higher initial lumens and 2915 or greater mean lumens, a Color Rendering Index (CRI) of at least 82 and a rated life of 24,000 hours or greater.

The three major fluorescent lamp manufacturers make lamps that meet these specifications. The GE-Starcoat HL, the Osram/ Sylvania-Octron 800 XPS and the Philips-Advantage T8 are the lamps families that comply. There seems to be two main reasons to use this lamp - higher lumens per watt and longer lamp life.

For the lumens per watt issue, using the mean lamp lumen data (lumens at 8,000 hours) and not including the ballast data (more later on ballasts) the 70 series lamps produce around 83.6 (2675/32) mean lumens per watt, the 80 series lamps produce around 87.5 (2800/32) mean lumens per watt and the "high performance T8" lamps produce around 92.0 (2945/32) mean lumens per watt. This is a 10% increase in light output over the standard 70 series T8, using the same wattage.

Figure 1 below does not fully tell the lamp life story. Using instant start ballasts, which make up between 70% - 90% of the market, on these rapid start lamps may shorten lamp life. Operating lamps longer than the industry standard test procedure of 3 hours per start will increase lamp life (see Fig 2.).

High Performance T8 lamps should be thought of as a system (lamp+ballast). Used by themselves they will produce 10% more light and last 20+% longer than standard T8's, but will save NO energy.

Combined with an industry standard lowpower instant start ballast (0.77 ballast factor) that uses 51 watts will have a 12% energy savings while producing almost as much light (96%). Using one of the new high-efficiency ballasts saves even more power (17%).

As an example: A 2-lamp F32T8/7xx at 2675 mean lumens on a standard instant start ballast (0.88 ballast factor) will use 58 watts and produce 4708 mean system lumens. A 2-lamp "high performance T8" at 2945 mean lumens on a high-efficiency low-power ballast (0.77 ballast factor) will use 48 watts and produce 4535 mean system lumens. A 4% reduction in mean lumens but it has a 17%reduction in power with a 20% increase in life.

Fig ig 1: High P Perfor erfor erformance mance T8 Systems Comparison

Fig ig 2: Lamp Life on Ballast Systems

Lamp life at 3 hours per start

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