From Architectural Engineering Design: Mechanical Systems


A light source is any natural or artificial illumination. In fact, windows and skylights may be considered as dimmer-operated 'daylight fixtures' fitted with clear surface-mounted lenses. The electric potential a light source utilizes is usually 120 volts, rarely more than this, and occasionally 12 or 24 volts; and their wattages vary widely. Considering that a common incandescent lamp uses 120 volts and 100 watts, the current it consumes is less than one amp. Thus a dozen such lamps can be installed on one 15 amp circuit.

In this chapter, each artificial light source has a letter designation as follows:






quartz, halogen, or tungsten-halogen






compact fluorescent



mercury vapor






high-pressure sodium



low-pressure sodium



high-density discharge (includes MV, MH, HPS, & LPS)



fiber optic



light-emitting or liquid-crystal display

In the above light sources, usually only 4-8 percent of each lamp's life cycle costs is spent on its initial cost while 80-88 percent is spent on the energy consumed during its rated life (the rest goes toward installation and maintenance labor). In the eyes of many, such inefficient 'lumen lemons' are a major source of waste in our energy-extravagant society. Thus the federal government has outlawed several inefficient R, PAR, and fluorescent lamps, which industry has replaced with more efficient models such as compact fluorescent lamps.

Many industries today are conducting extensive research in new kinds...

Products & Services
Pilot Lights and Indicator Lights
Pilot lights and indicator lights are indicating lights for machines or instruments. Most indicators favor the use of LEDs or incandescent lamps.
Lampholders are mechanical devices that support lamps and connect them to electrical circuits. They hold light bulbs and make electrical contact to provide a bulb with power.
Lighting Inverters
Lighting inverters provide alternating current (AC) power for indoor, outdoor and emergency lighting, signage, and associated controls.
Lamps are light sources that emit incoherent light for illumination. There are many different types of products. Examples include fluorescent lamps, halogen lamps, heat lamps, incandescent lamps, LED lamps, projection lamps, spectral lamps, and stage lamps. Specialized and proprietary lamps are also available.

Topics of Interest

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The U.S. Department of Energy has announced new energy-efficiency legislation that will impact the manufacture of incandescent light bulbs, linear and U-shaped fluorescent lamps, and PAR lamps. For...

Overview Electric lighting has brought about a significant improvement in the standard of living for millions of people all over the world. The availability of bright, instantly available...

Streetlight systems have developed gradually from candles in the seventeenth century to gas lighting in the eighteenth century and electric lighting in the twentieth century. The first electric lights...