Author Topic: How bright are metal halide bulbs supposed to be?  (Read 655 times)
RadiantMV
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How bright are metal halide bulbs supposed to be? « on: December 18, 2021, 04:24:48 PM » Author: RadiantMV
This is probably a really stupid question as I’m not an expert on lights, but today i lit my first metal halide bulb on the 400 watt M59 ballast i normally use for mercury vapor bulbs, and it was so much brighter than any 400w MV I’ve lit. Are metal halides normally brighter than MVs or is it just because I’m using the intended bulb for the ballast?
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sol
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Re: How bright are metal halide bulbs supposed to be? « Reply #1 on: December 18, 2021, 06:09:34 PM » Author: sol
Metal halide lamps have more lumens than mercury vapour. However, M59 lamps, like all quartz MH lamps, loose quite a bit of lumens over their lifetime. Mercury vapour lamps loose lumens as well, but having a longer life, the decrease is more gradual than metal halide.

Some medium and high wattage mercury vapour lamps have been known to last very long, and loose most of their lumens. Some give light equivalent to a 40W incandescent despite being 250 or 400 watts. When this happens, the lamp still consumes its rated power, making them quite inefficient.
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Joe Maurath, Jr.
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Re: How bright are metal halide bulbs supposed to be? « Reply #2 on: December 18, 2021, 08:07:59 PM » Author: Joe Maurath, Jr.
Metal halide lamps have more lumens than mercury vapour. However, M59 lamps, like all quartz MH lamps, loose quite a bit of lumens over their lifetime. Mercury vapour lamps loose lumens as well, but having a longer life, the decrease is more gradual than metal halide.

Some medium and high wattage mercury vapour lamps have been known to last very long, and loose most of their lumens. Some give light equivalent to a 40W incandescent despite being 250 or 400 watts. When this happens, the lamp still consumes its rated power, making them quite inefficient.

The longest-lived MV lamps I have personally seen were a couple CD 175W KenRads; BT-28 with /W phosphor. They operated untouched in dusk-to-dawn Wheeler horizontal MV fixtures on a local municipal light department system from 1965 to 2016. They and these fixtures were removed that year in favor of LED. One of the lamps was not working at the time of removal and the other was. I missed out regarding the EOL one but I was fortunate to get the working one, complete with the fixture from the utility. Its arc tube is pretty black and the lamp illumination is about equivalent to a 100W incandescent or maybe a little better.
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