I am referring to those linear tungsten halogen light bulbs often used by domestic floodlights for outdoor use. These bulbs are 117mm long.
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Do other 117mm bulbs (300 W, 500, etc) have a lumen output proportional to their power consumption which is equivalent to one another? IYSWIM.
Not necessarily. The efficacy of a lamp, measured in lm/W, is a function a number of design parameters, perhaps most importantly the filament temperature which determines the trade-off between light output and life. It seem to be an easy matter to check the lamp specs.
Light output should be reasonably proportional to power input for a given technology. Will probably vary from make to make.
Just for info halogen lamps aren't particularly efficient. In the UK an energy efficient lamp as defined as producing more than 40 lumens per watt. I think only flourescent lamps can meet that but some prototype LEDs are are also in the ballpark (but not yet commercially available I think?)
IIRC high pressure metal halide lamps are much more efficient than fluorescents
Actually, linear fluorescents are slightly better than metal halide lamps, although there isn't much in it. Other high intensity discharge lamps will do better, although their colour rendering is not as good.
I disagree. Linear T8 and T5 fluorescent lamps operate with an initial efficacy of 100 lm/W or better on electronic ballasts and have mean efficacy values that are just about
95% of the initial (100 hour) efficacy values.Pulse start MH lamps have about the same initial efficacy, but their mean efficacy values are only about 70% of the initial value, and that's for a 15,000 lamp vs 20,000 hours for the linear fluorescent lamps. Conventional metal halide have lower initial efficacy values until move up to the very large sizes. For example, one GE 250-watt metal halide has an initial efficacy of only 83 lm/W and a mean efficacy of
54 lm/W. On the other hand a 1650-watt GE metal halide lamp has a respectable initial efficacy of 107 lm/W, but the rated life of this lamp is only 3000 hours and the mean efficacy value is 88 lm/W.CMH lamps still don't beat fluorescent in raw efficacy. A
400-watt Philips MasterColor CMH lamp has an initial efficacy of about 87.5 lm/W and a mean efficacy of 74.4 lm/W while having a rated life of 15,000 hours. A 70-watt Philips MasterColor CMH lamp has an initial efficacy of 94 lm/W, and a mean efficacy of 71 lm/W. So, the performance does vary with the type and size of the CMH lamp, but I can't find any that have higher efficacy than good 4-foot fluorescent lamps.Now, before I get beat over the head I must state that I know there are factors to consider other than raw efficacy. Each lamp type has advantages and disadvantages in specific applications. I am only responding to your comment that high pressure metal halide lamps are mush more efficient than fluorescent lamps..
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