The light generated by light sources is measured in lumens. In order to provide consistent information in an ever-changing field, lamps are tested according to prescribed procedures to determine the quantity of light. The principal result of such tests is the rated lumen value for a lamp.
Rated lumens for a lamp are the amount of light expected from that version of that manufacturer's lamp under ideal and closely constrained conditions. Electrical power, waveform and cycle, air temperature and many other conditions have criteria to be met. The ballast used in testing is an extremely sensitive and impractical version, and typically produces more light from lamps than "real world" ballasts do.
In most cases, installed combinations of lamps and ballasts will not produce as much light as the rated lumens even under initial conditions.
Data from (the leading manufacturer of MH lamps) Venture's 2000 catalogue (p 21) shows that the values for rated lumens from pulse start metal halide lamps depend on whether the lamp is in a vertical or horizontal position. The values are listed as 9000 for vertical and 8100 for horizontal position. Venture's ballasts for such lamps (p 22) have input power ranging from 118 to 128W, depending on the quality of the ballast considered. The corresponding initial efficacy values are 70 to 76 lumens per Watt for a vertical position and 63 to 69 for horizontal lamps.
From the same Venture catalogue (p 131) the ballasts for 100W HPS lamps consume 118 to 132 Watts. From the General Electric 1999 catalogue of lamps (p 3-15), the rated lumens are listed at 9500 for any burning position. The corresponding initial efficacy values are between 72 and 81 lumens per Watt.
Table 1: Rated Lumens and Initial Efficacy of 100W Sources Source/Description Rated Lumens Input Watts Initial Efficacy MH 100W vertical 9000 118-128 70-76 100W horizontal 8100 118-128 63-69 HPS 100W (any position) 9500 118-132 72-81
Table 2 shows lamp lumen and input power data from the Advanced Lighting Guidelines 1993 and 2001 for various MH and HPS lamps. The pulse start variety of MH lamps, which includes the 100W lamps discussed above, are identified as MHPS, to distinguish them from the conventional metal halide lamps listed as type MH. The 100W lamps are included, using the lowest wattage of the range shown in Table 1.
Table 2: Rated Lumens and Initial Efficacy of HID Sources Type Wattage RatedLumens Input Watts Initial Efficacy (nominal) (lumens) (W) (lumens/W) HPS 35 2250 45 50 HPS 50 4000 65 62 HPS 70 6400 85 75 HPS 100 9500 118 81 HPS 150 16000 166 96 HPS 200 22000 240 92 HPS 250 27500 295 93 HPS 400 50000 460 109 HPS 1000 140000 1080 130 MH 175 13500 210 64 MH 250 20500 295 69 MH 400 36000 455 79 MH 1000 110000 1080 102 MHPSv 100 9000 118 76 MHPSh 100 8100 118 69 MHPS 175 17500 210 83 MHPS 250 21500 295 73 MHPS 400 44000 455 97
A handy one page summary of the rated lumens for various outdoor sources - based on 2003 catalogues - is available here (pdf format, 9 kb).
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last changed on 5 Oct 04