A plain-text photometric file in the LM-63 format containing the luminaire's lumens, dimensions, input watts and a table of candela values at measured angles. Calculation and rendering software reads it to predict illuminance, uniformity, glare and BUG ratings. EULUMDAT, with the .ldt extension, is the European equivalent. Using the wrong file, or a file for a different lumen package, invalidates a whole design.
Rep sent the IES file for the 3000 lumen version, we specified 4000, so every number in the calc is low.
Open the file in a text editor before using it: the header lines show the test lab, lumens and catalog number, and catch the wrong-file mistake in seconds.
Also heard as
- photometric file
- IES
- .ies
- LM-63 file
Related terms
Goniophotometer
An instrument that measures a luminaire's light intensity in every direction by turning the luminaire, or a mirror around it, relative to a detector.
Point-by-point
A lighting calculation that predicts illuminance at each point on a grid from every luminaire's photometric data.
Luminous intensity
How much light a source sends out in one specific direction, measured in candelas.
BUG rating
An outdoor luminaire rating for backlight, uplight and glare, each scored 0 to 5, used in light pollution ordinances.
Cut sheet
The one- or two-page manufacturer data sheet for a luminaire, with dimensions, photometry and ordering options.