footcandle


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Related to footcandle: lumen

footcandle

[′fu̇t ‚kand·əl]
(optics)
A unit of illumination, equal to the illumination of a surface, 1 square foot in area, on which there is a luminous flux of 1 lumen uniformly distributed, or equal to the illumination of a surface all points of which are at a distance of 1 foot from a uniform point source of 1 candela; equal to approximately 10.7639 lux. Abbreviated ftc.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

illuminance

The density of luminous power, also called illumination. One lumen of luminous flux, uniformly incident on 1 square foot of area, produces an illuminance of 1 footcandle; in SI units, one lumen of luminous flux, uniformly incident on 1 square meter of area, produces an illuminance of 1 lux.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
* The replacement of lighting equipment by more efficient devices providing the same 500 lux (46.5 footcandle) illumination with a reduced electric power (from 10.6 W/[m.sup.2] to 6 W/[m.sup.2] [from 3.36 Btu/h.[ft.sup.2] to 1.90 Btu/h.[ft.sup.2]]), provides 18% final electricity consumption energy savings.
Maintaining good color recognition from high-pressure sodium lamps, Bullough says, can be achieved by using at least 3 footcandles of illumination.
Since the American Standard Recommendation prescribes illumination in terms of footcandles on the horizontal plane and emphasizes reduced glare, there has been a tendency to use luminaires with sharp cutoffs of the main beam, which directs the light predominantly down onto the pavement surface.
For championship play, 35 footcandles or over maintained evenly distributed - within 10 percent - and measured with a light meter about 42 in.
Measuring footcandles. Basic to the process of measuring footcandles is the availability and use of the proper measuring device.
A parking lot generally requires O.S footcandles for security, and you can achieve that a lot more easily with today's optics and not waste any light.
You don't need the same type of lamps in every area--for example, in Research & Development, we need 72 footcandles at the desktop because they do fine work, but we don't need 72 footcandles at the floor level in the warehouse.
The formerly washed-out parking area is now cheerfully lit, with an average light level of 3.1 footcandles (a 109% increase) and uniformity at an average/minimum ratio of 4.4:1.
Consult the Illuminating Engineering Society's footcandle recommendations for different tasks and age groups to see if you're overlighting any areas.
Although the light offers excellent efficiency when it comes to overall footcandle output, it is weak in the area of distribution and overall uniformity.
The starring role will be played by a light meter, which measures the footcandle level on either a horizontal plane (the top of a desk) or a vertical one (the wall).
For more than half a century, the IES, through the efforts of the Recommendations on Quality and Quantity (RQQ) Committee and then its successor, the Quality of the Visual Environment (QVE) Committee, searched for a way to provide and identify a "good" footcandle, one that minimizes direct glare and optimizes the occupant's visual performance rate.