Light_vocabulary

= VOCABULARY =


 * Alabaster**: genuine alabaster is a very fine variety of crystalline gypsum (hydrous calcium sulfate) found in nature. It is __ [|translucent] __ and its color is often white, pearly, or silky colorless but it, more often than not, has subtle reddish-brown bands of iron oxide running through it. It is often used for decorative objects such as light fixtures or figurines. Some light fixtures use //**faux**// alabaster, which is usually man-made glass. Both genuine and faux alabaster can be very attractive. The faux alabaster is generally much less expensive while real alabaster can lose some of its coloration over time. Real alabaster is expensive simply because quarrying it is costly and there is huge amount of waste when it is shaped, finished, and polished. Genuine alabaster is a minimum of 3/8in thick and weighs at least twice as much as imitations and has translucent and dark bands that are completely random in shape, size, and location. Since alabaster is a soft, porous stone it should be treated gently and never cleaned with detergents or abrasives. Instead, wipe alabaster with a slightly damp (not wet), soft cloth. Furthermore, heating alabaster for long periods of time with a high-wattage light bulb may drive out the residual water in the alabaster and turn it completely white.


 * Baffle**: in lighting this is usually a grooved surface that deflects and controls the “flow” of light to soften it and minimize reflected glare. Baffle trims (sometimes called step baffle trims or stepped baffle trims), made of plastic or metal, are often integral parts of recessed downlights. They are often colored a flat black to absorb some of the light but can have other finishes such as flat white, brushed copper, or brushed nickel.


 * Ballast**: an electrical device used with __ [|fluorescent] __ and __ [|HID] __ (high intensity discharge) lamps (light bulbs) to supply sufficient __ [|voltage] __ to start and operate the lamp but then to limit the current during operation


 * Basket Troffer**: a troffer whose light sources are concealed by curved opaque shielding called "baskets", which are often perforated with a pattern of small holes. This type of troffer provides both direct lighting through the perforations and indirect lighting by bouncing light up from the basket and then off the upper light-colored opaque parts of the troffer.


 * Beam Spread**: a measure of the spread of light from a reflectorized light source, a special-shaped lamp with a reflective coating inside the bulb to direct the light forward. The beam spread may be very narrow (narrow spot), very wide (wide flood), or something in-between (narrow flood, for example). Examples of "reflectorized light sources" are MR11, MR16, PAR20, PAR30, PAR38, R40, ER30, and BR30 lamps.


 * Chandelier**: a chandelier is often the focal point of the dining room. As such it should be hung about 30 inches above the tabletop and should be at least 6 inches narrower than the table on each side.


 * Circline**: a type of fluorescent lamp that is made up of a circular tube of glass; when placed in a light fixture the ballast that powers this type of lamp is usually located in the center of the circline lamp


 * Faceplate**: the metal or plastic plate installed over an on/off switch, dimmer, or receptacle, which covers the wall opening and protects the wiring inside the junction box


 * Floodlight**: a broad-beamed high intensity artificial light source


 * Foot-Candle**: the amount of light reaching a subject. The commonly United States unit of measurement of lighting level (illumination) is the foot-candle (fc). The international unit of measurement of lighting level (Illumination) is the lux (lx). The relationship between the lux and the foot-candle is 1 fc = 10.76 lux.


 * Four-Way Switch**: a wall switch that allows three switches like this to control one lighting system. Whenever you flip one of the four-way switches in a given circuit, the light changes its state; that is, if the light was on, it then turns off and if the light was off, it then turns on.


 * IP Ratings**: Ingress Protection (IP) ratings, developed by the European Committee for Electro Technical Standardization, are used to specify the environmental protection an enclosure provides to the electrical equipment inside that enclosure. An IP rating normally has two numbers associated with it: (1) protection from solid objects or materials and (2) protection from liquids (water).


 * R Lamp**: an __ [|incandescent] __, cone-shaped, light bulb that has a reflecting surface on the inside rear of the glass envelope. Variations of this lamp type are the bulged reflector lamp (BR), the ellipsoidal reflector lamp (ER), and the small reflector lamp (R). Since mid-2008 BR and ER light bulbs greater than 65 watts, used mostly in commercial retail applications, have been outlawed from being manufactured. These banned light bulbs can be replaced with more-efficient halogen PAR light bulbs. Also since mid-2008, R20 light bulbs can be no more than 45 watts. If a higher wattage reflector-type lamp is needed, a more efficient halogen PAR20 light bulb can be used. The 65-watt BR30 light bulb, commonly used in homes and restaurants, may still be manufactured and sold.


 * Tandem Wiring**: a type of electrical wiring that shares one ballast located inside a single fluorescent light fixture with one or more other fluorescent fixtures. This technique is used to reduce the cost of the lighting system, reduce the cost of maintaining the lighting system, and reduce the cost of the electrical energy needed to power the lighting system.


 * Torchiere**: a tall floor lamp that provides indirect lighting with its light source located within a reflecting bowl that directs the light upward, which then reflects off the ceiling

Formulae: watts = volts x amps, P = V x I, electrical power = electromotive force x electric current.
 * Wattage**: the amount of electrical //power// consumed by a lamp or light fixture measured in “watts”. One watt is equal to the power dissipated by 1 ampere of electrical current flowing across a resistance of 1 ohm //**or**// the power produced by 1 ampere of electrical current under an electromotive force of 1 volt. One horsepower is equal to 746 watts.