Instant-start ballasts

There are some very persuasive arguments for the use of instant-start electronic ballasts; the laboratory lighting designer should consider them before deciding which electronic ballast to specify.

• The instant-start ballast is more economical—5 to 10 percent less expensive—than the rapid--start ballast. This can become a significant difference given the numbers of ballasts required to operate an entire lab complex. The instant-start ballast will also provide greater energy savings of about two watts per lamp. The rapid-start ballast uses more energy because it must maintain current to the cathode to maintain cathode heat; the instant-start ballast essentially blasts the cathode into operation, so it does not require constant current to maintain lamp operation. Two watts per lamp multiplied by thousands of lamps in a laboratory can have a significant impact on energy use.
• In typical settings, lamps are on for periods of time greater than three hours per start. Lamp life tends to even out between the lamps driven by rapid- and instant-start ballasts after about eight hours of continual operation, so reduced lamp life resulting from instant ballasts becomes irrelevant under these conditions.

Designers should be aware that both types of ballasts are reliable and proven technologies. The particular areas where instant-start ballasts may not be used are defined clearly. All major ballast manufacturers produce both rapid-start and instant-start ballasts, so designers can easily select the product most applicable for a particular facility.