Volume 9 Issue 3
May 2000    
A-lamp - The incandescent lamp most commonly used in North American households. The "A" designation refers to the lamp's bulbous shape. ballast - A device required by electric-discharge light sources such as fluorescent or HID lamps to regulate voltage and current supplied to the lamp during start and throughout operation. bi-level switching - Control of light source intensity at two discrete levels in addition to off. compact fluorescent lamp (CFL) - A family of single-ended fluorescent-discharge light sources with small-diameter [16-millimeter (5/8-inch) or less] tubes. continuous dimming - Control of a light source's intensity to practically any value within a given operating range. tri-level switching - Control of light source intensity at three discrete levels in addition to off. indirect lighting - Light arriving at a surface after reflecting from one or more surfaces (usually walls and/or ceilings) that are not part of the luminaire. lamp - A radiant light source. luminaire - A complete lighting unit consisting of a lamp or lamps and the parts designed to distribute the light, to position and protect the lamp(s), and to connect the lamp(s) to the power supply. (Also referred to as fixture.) correlated color temperature (CCT) - A specification for white light sources used to describe the dominant color tone along the dimension from warm (yellows and reds) to cool (blue). Lamps with a CCT rating below 3200 K are usually considered warm sources, whereas those with a CCT above 4000 K usually considered cool in appearance. Temperatures in between are considered neutral in appearance. Technically, CCT extends the practice of using temperature, in kelvins (K), for specifying the spectrum of light sources other than blackbody radiators. Incandescent lamps and daylight closely approximate the spectra of black body radiators at different temperatures and can be designated by the corresponding temperature of a blackbody radiator. The spectra of fluorescent and LED sources, however, differ substantially from black body radiators yet they can have a color appearance similar to a blackbody radiator of a particular temperature as given by CCT. direct light - Light emitted by a luminaire in the general direction of the task to be illuminated. The term usually refers to light emitted in a downward direction. halogen lamp - An incandescent lamp that uses a halogen fill gas. Halogen lamps have higher rated efficacies and longer lives than standard incandescent A-lamps. active power - the system input power (in watts) for a lamp-ballast combination. color rendering index (CRI) - A rating index commonly used to represent how well a light source renders the colors of objects that it illuminates. For a CRI value of 100, the maximum value, the colors of objects can be expected to be seen as they would appear under an incandescent or daylight spectrum of the same correlated color temperature (CCT). Sources with CRI values less than 50 are generally regarded as rendering colors poorly, that is, colors may appear unnatural. efficacy - The ratio of light output (in lumens) to input power (in watts), expressed as lumens per watt (LPW). illuminance - The density of luminous flux incident upon a surface. Illuminance is measured in footcandles (lumens/square foot) or lux (lumens/square meter). One footcandle equals 10.76 lux. lamp life - The number of hours at which half of a large group of lamps have failed when operated under standard testing conditions. lumen (lm) - A unit measurement of the rate at which a lamp produces light. A lamp's lumen output rating expresses the total amount of light the lamp emits in all directions per unit time. metal halide lamp - A high-intensity discharge (HID) lamp that uses mercury and several halide additives as light-producing elements. Metal halide lamps have better color properties than other HID lamp types because the different additives produce light distributed over more visible wavelengths, resulting in a more complete spectrum. Metal halide lamps are available with CCTs from 2300 to 5400 K and with CRI values from 60 to 93. Efficacies of metal halide lamps typically range from 75 to 125 LPW.
How efficient are the torchieres?

The following table summarizes data provided by the manufacturers or tested by NLPIP. NLPIP noticed that measured active power differed from rated active power for several torchieres. This difference can affect efficacy, operating cost, and light output.

Table 3. Torchiere Light Output and Efficacy

Lamp Type Number & Type(s) of Lamps in Torchiere CCTa CRIa Rated Light Output from Lamp(s) (lm)a Rated Active Power (Including Ballast) (W)a Measured Active Power (Including Ballast) (W)b Rated Efficacy (lm/W)c

Halogen one 300-W tubular double-ended halogen 3050 95+ 4800–6000 300 300 16–20

one 3-way (50-100-
150-W) incandescent
2800 95+ 2220 150 147 15

Quad CFL three 26-W quad-tube CFLs 2700–3500 83 5400 80 74 68

Flat CFL two 36-W flat CFLs 3000–4100 82 5600 65 65 86

Circular CFL one 20-W circular CFL and one 30-W circular CFL 2800 84 3800 55 37 69

Long CFL two 40-W long twin-tube CFLs 3000–4100 82 5800 95 82 61

Metal Halide one 68-W metal halide and two 25-W incandescents 3200 75 6000 68 73d 88

a Information taken from lamp packaging or manufacturer's information.
b Measured by NLPIP at maximum switched setting.
c Calculated from rated light output and rated active power.
d With the incandescent lamps switched off.

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