Key Components of Lighting
Ballasts
The ballast regulates the current drawn by the lamp, and is the heart of any fluorescent fixture. There are several types and grades of ballasts to accomplish this end.
| Component | Description |
|---|---|
| Preheat ballasts | Preheat type ballasts require a starter. The preheat ballast typically wastes only about 2 watts or less energy to heat, and it can be used to start fluorescent lamps down to 0 degrees. |
| Outdoor ballasts | Underwriters Laboratory (UL) Type 1 preheat ballasts contain no materials which might absorb moisture, and are required in damp location fixtures. Outdoor preheat ballasts are sometimes mistakenly called cold weather preheat ballasts. Outdoor ballasts are potted in tar, and are suitable for wet location fixtures exposed to direct water spray. The actual ballast is the same; the packaging is different. |
| Rapid start ballasts | There are standard rapid start ballasts, low heat ballasts, very low heat ballasts, and super low heat ballasts. A rapid start ballast operates at about 180 degrees. Every 10 degree rise above 180 degrees will reduce the average life of a ballast by half. If a fixture is cycling on and off during operation, it is because the ballast is exceeding the 205 degrees set by the thermal cut out device in the ballast. The ballast is running too hot, and obviously will fail much sooner than necessary. Upgrading to a low heat, very low heat, or super low heat ballast is recommended. The ballast grade required depends upon the heat dissipating ability of the fixture, the heat conductivity of the mounting surface of the fixture, and prevailing line voltage. There are cold weather, rapid start ballasts capable of starting a fluorescent lamp below 50 degrees; however, you must specify this requirement to the manufacturer. The quality of a magnetic ballast or its ability to control lamp current to a predefined value over a wide range of line voltage, and its operating temperature are a function of the quality of the magnetic material in the ballast core, the cross section of the core, and the gauge of the copper wire used. |
| Electronic ballasts | Electronic ballasts are available for several lamps; however, most electronic ballasts available today are for the 4- and 8-foot fluorescent lamp. These ballasts drive the lamp at high frequency, provide improved lumen output, and exhibit very low energy loss in the ballast. Some manufacturers claim double the life expectancy of a magnetic ballast. |
Other Key Components
| Component | Description |
|---|---|
| Diffusers | Diffusers are made of non-yellowing acrylic, never styrene, and are either injection molded, vacuum formed, or extruded. Polycarbonate diffusers are used on vandal resistant fixtures and appear as options on certain other fixtures providing an optional vandal resistant design. |
| Shielding | Shielding is provided as non-yellowing, clear prismatic acrylic. Either silver or gold parabolic louvers can be specified as options in either 1/2- or 1 1/2-inch cells. Polarizing shielding should be considered for computer facilities where reducing the veiling reflections in a monitor is of paramount importance. |
| Reflectors | Silver film over aluminum reflectors is provided where specified. The reflectors either snap into tabs provided in the back of the fixture, or are held using studs in the fixture body. |