Alliance for Lighting Information

Rated Lamp Lumens and Initial Efficacy

by David M. Keith

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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