Fluorescent Fixture Types

Pre-Heat

• Pre-heat fixtures must heat the gas inside the fluorescent tube before emitting any light. A mechanism known as a starter heats the gas. Starter designs can be automatic or manual. To start the fluorescent lamp, the starter sends electricity to the electrodes for a second or two, warming the gas. The starter electronically senses if the gas is warm enough to conduct electricity and will send more current until the gas is heated enough to conduct electricity and begin the fluorescent light-creating process. Fixtures with manual starters, such as an older desk lamp, require the "on" button to be pressed for a few seconds, allowing electricity to flow and heat the gas inside the fluorescent tube. Once the lamp begins to emit light, the "on" button is released. Starters in many fluorescent fixtures are small cylinder-shaped pieces of metal and are replaceable, while some low-cost units are not.

Rapid-Start

• Rapid-start fluorescent fixtures do not incorporate a starter to begin the light-emitting process. Fixtures containing multiple fluorescent tubes are commonly designed as rapid-start. These utilize a regulator called a ballast that controls the amount of electricity flowing to the electrodes. In some cases, the ballast allows a small amount of electricity to flow to the fixture at all times. At start-up, the ballast provides a high-voltage flow to the light tube and a metal strip within the fixture. At this point, a dim glow of light appears. This initial heating process spreads through the glass tube as the ballast continues to provide current to the electrodes. As the gas heats and conducts more electricity, the fluorescent light becomes brighter. Rapid-start fixtures emit a dim light nearly instantly and begin to brighten to their full potential over a few seconds.

Instant-Start

• The ballast of an instant-start fixture sends a high-voltage burst to the fluorescent tube to begin the lighting process. Instant-start fixtures do not require electrodes and begin to glow at full brightness immediately upon starting. Once the light process has begun, the ballast will adjust the voltage as necessary to maintain proper light level.

Compatibility

• Both pre-heat and rapid-start fluorescent lights require filaments to operate. Because of this, in most cases, a rapid-start lamp may be used in a pre-heat fixture. However, using a pre-heat lamp in a rapid-start fixture is not always possible since many pre-heat type tubes are smaller than rapid-start types.