Fluorescent Lamps

PROJECTOR LAMPS are installed in indoor and outdoor display lighting fixtures. They use a self- contained reflector but have an advantage over the reflector type since they are suitable for extreme temperature conditions and provide more accurate light control. HEAT AND DRYING LAMPS, available with built-in reflectors or with separate reflectors, are an inexpensive answer to a requirement for instantaneous infrared energy. The reflector bulb keeps the initial cost to a minimum and provides a new reflecting surface with each new lamp. HARD-GLASS LAMPS, made of special glass with high resistance to thermal shock, are effective where rain, splashing liquids, insects, snow, fixture parts, or hot metallic spray may touch the glass bulbs. VIBRATION SERVICE LAMPS are available that withstand excessive vibration that cannot be eliminated by flexible fixture mounting. Where the lamp will be subjected to shock, such as at the end of a drop cord or near machinery, you will want to select ROUGH SERVICE LAMPS. With filament supports, these lamps can withstand severe shocks without failure. High-cost replacement areas, such as towers, industrial high bays, theater marquees, halls, and stairwells, are lighted with LONG-LIFE LAMPS. QUARTZ-IODINE LAMPS offer a concentrated source of incandescent light with excellent light control characteristics, good color, and a life twice that of regular general service incandescent lamps. They depreciate at a lower rate than the general service lamp. The lamp cost is considerably higher, however, than a general service lamp, and a special fixture is required. FLUORESCENT LAMPS There are two principal types of fluorescent lamps: instant-start and rapid-start preheat lamps. Both have practically the same physical dimensions but different internal construction. The type of circuit in which the lamp should be used is etched on the end of the lamp. The rapid-start preheat lamp operates satisfactorily with either the preheat or rapid-start circuits. It has a short lamp life in an instant-start circuit. The instant-start lamp operates satisfactorily with an instant-start ballast, burns out the ballast in a rapid-start circuit, and does not light in a preheat circuit. Preheat lamps dominated the field for many years but are no longer considered a major type. They continue to be in use, however, particularly in fixtures using lamps smaller than 40 watts. Examples of circuits for the major types are readily found in current manufacturers’ publications. Example of some circuits are shown in figure 5-76. The 4-foot rapid-start lamp is the preferred lamp for most applications. Figure 5-76.—Representative fluorescent circuits. 5-43