Dimming a Metal Halide (MH) Bulb, is it ok? Yay or Nay?

In your experience, will dimming an MH bulb reduce the life of the bulb?

  • Total voters
    4
Pazzo

Pazzo

Well-Known Member
I've been doing research for hours now trying to find real definitive proof if dimming a Metal halide bulb in a dimmable ballast is ok or not overall, from what I've read dimming an HPS bulb doesn't seem to matter at all but with MH people can't seem to agree. I've seen so many mixed opinions from "it'll kill the bulb" to "it's perfectly fine and changes nothing" so there's mixed opinions to say the least...

I did read a page from the manufacture that said the Lumatek ballasts (that I have) can be dimmed and it does NOT affect the light spectrum of the bulb like some people think, it simply dims the bulb. And it is suggested to always use the highest watt bulb for said ballast and dim it instead of buying smaller watt bulbs (so if you have a 1000w ballast and you want to dim it to 600w you should still use a 1000w bulb) So that answered half of what I was looking for..

The main question I have left is if I indeed dim my MH bulb will it reduce the life of the bulb dramatically? I would really like to know this from someone who has actually done this and not someone who has just read everything I just got done reading online. I'm probably going to just buy some cheap bulbs and test it myself but it would be nice to know from someone who has already done it.. I can't be the only one wondering this and it would be nice to get a definitive answer.

Thanks fellas,

-Pazzo
 
L

Lurr

New Member
I work in the industry. Dimming bulbs has always been intended as an emergency measure and has never been intended to be a long term option. The problem isn't bulb degradation but spectrum output. A 1000w MH is built to produce it's marketed spectrum at 1000w. Lower the power input and you alter that spectrum. If you don't believe me plug in a 1000w horti blue and dim it down to 600w and watch it turn green. Will it still grow a plant? Yes. Will it grow a plant as well as it could? No.‎
 
Pazzo

Pazzo

Well-Known Member
Lurr said:
I work in the industry. Dimming bulbs has always been intended as an emergency measure and has never been intended to be a long term option. The problem isn't bulb degradation but spectrum output. A 1000w MH is built to produce it's marketed spectrum at 1000w. Lower the power input and you alter that spectrum. If you don't believe me plug in a 1000w horti blue and dim it down to 600w and watch it turn green. Will it still grow a plant? Yes. Will it grow a plant as well as it could? No.‎
Click to expand...
I have seen comments from people who have contacted the manufacturer and asked that exact question and they said it doesn't change the spectrum output but just the actual light/lumens it puts out from the tests they've done themselves. Could they be lying? Who really knows, that's why I was wanting to see what peoples actual experiences are.
 
Renfro

Renfro

Well-Known Member
Pazzo said:
The main question I have left is if I indeed dim my MH bulb will it reduce the life of the bulb dramatically?
Click to expand...
Has anyone actually tested this, like in a side by side? Maybe, maybe not. Honestly, who cares. Do what you gotta do and when the bulb no longer puts out get another.

I would think that a dimmed bulb might actually last longer, so long as the arc is stable.
 
Renfro

Renfro

Well-Known Member
The following is cut from this article:

High-pressure sodium lamp dimming

According to Guidelines for The Application of Dimming to High-Intensity Discharge (HID) Lamps (LSD 14-2010) published by the National Electrical Manufacturers Association (NEMA), most high-pressure sodium lamps are approved for dimming in any orientation, although dimming performance may vary depending on whether the ballast is magnetic or electronic; consult the lamp manufacturer.

NEMA recommends that high-pressure sodium lamps not be dimmed below 50% of rated lamp power. Dimming below the recommended minimum can significantly degrade lamp life—potentially voiding lamp warranties—while also affecting efficacy, color and lumen maintenance. For retrofit metal halide lamps designed to operate on high-pressure sodium ballasts, and specialty high-pressure sodium lamps (e.g., internal ignitor, etc.), consult the lamp manufacturer about whether dimming is allowed and resulting parameters and limitations.

Besides dimming range, NEMA recommends that high-pressure sodium lamps be operated at full light output for at least 15 minutes before dimming. If a voltage interruption extinguishes the lamp, the timer should be reset only after the lamp has restarted. For more information, consult the Guidelines.

Note that dimming some high-pressure sodium lamps and retrofit metal halide lamps can result in changes to color temperature, color rendering and efficacy. NEMA further points out that high-pressure sodium lamps are susceptible to “drop out”—sudden extinguishment—if rapidly dimmed after the lamp operates for about 15,000 hours. Users may confuse this with the lamp having failed; if the user allows the lamp to cool, the lamp will relight and operate at its rated wattage for its rated life in an undimmed mode. To reduce the potential for this, NEMA recommends slowing the dimming rate to about 1.5 minutes from full output to maximum dimmed condition (while maintaining sufficient voltage to sustain the arc).

Metal halide lamp dimming

Dimming is possible with pulse- and probe-start quartz metal halide lamps, pulse-start ceramic metal halide lamps and many types of specialty lamps, such as lamps with internal ignitors or starting aids that operate on probe- and pulse-start metal halide ballasts. NEMA does not recommend dimming for self-extinguishing T-type metal halide lamps and retrofit high-pressure sodium lamps designed to operate on metal halide ballasts.

NEMA recommends that metal halide lamps not be dimmed below 50-70% of lamp power, depending on the lamp type, for the same reason as high-pressure sodium lamps—to dim below recommended levels may degrade lamp life, efficacy, color and lumen maintenance. Below is the recommended dimming range for each type of metal halide lamp, per NEMA:

• 100% to 50% of rated lamp power for probe-start quartz metal halide lamps;
• 100% to 60% of rated lamp power for 150W or smaller pulse-start quartz metal halide lamps;
• 100% to 50% of rated lamp power for >150W pulse-start quartz metal halide lamps;
• 100% to 70% of rated lamp power for <150W ceramic pulse-start metal halide lamps; and • 100% to 60% of rated lamp power for 150W or larger ceramic pulse-start metal halide lamps. For specialty metal halide lamps, consult with the lamp manufacturer about allowable dimming and wattage range. [caption id="attachment_3913" align="alignnone" width="404" caption="Correlated color temperature shift for quartz metal halide lamp across dimming range. Image courtesy of NEMA."]
[/caption]

As with high-pressure sodium lamps, NEMA recommends that metal halide lamps be operated at full light output for at least 15 minutes before dimming. If a voltage interruption extinguishes the lamp, the timer should be reset only after the lamp has restarted. For more information, consult the Guidelines.

Manufacturers limit the operating position of probe-start lamps to the base-up position if the lamp is to be dimmed. Most pulse-start quartz and ceramic metal halide lamps may be dimmed in any operating position, with some exceptions, including ceramic metal halide lamps 150W and larger; consult the lamp manufacturer for specific information about allowable dimming and operating position for the selected lamp type.

Note that metal halide lamps typically experience some degree of color shift during dimming; clear quartz lamps, for example, may exhibit a significant increase in color temperature, with the shift extending to as high as 5000-6000K compared to the typical 3000-4000K. The color shift in a phosphor-coated lamp may be much less pronounced. For example, a 3700K coated lamp may increase to just 4000K during dimming.

Additionally, as with high-pressure sodium lamps, lamp efficacy and color rendering may decline with dimming.
 
PadawanWarrior

PadawanWarrior

Well-Known Member
Renfro said:
The following is cut from this article:

High-pressure sodium lamp dimming

According to Guidelines for The Application of Dimming to High-Intensity Discharge (HID) Lamps (LSD 14-2010) published by the National Electrical Manufacturers Association (NEMA), most high-pressure sodium lamps are approved for dimming in any orientation, although dimming performance may vary depending on whether the ballast is magnetic or electronic; consult the lamp manufacturer.

NEMA recommends that high-pressure sodium lamps not be dimmed below 50% of rated lamp power. Dimming below the recommended minimum can significantly degrade lamp life—potentially voiding lamp warranties—while also affecting efficacy, color and lumen maintenance. For retrofit metal halide lamps designed to operate on high-pressure sodium ballasts, and specialty high-pressure sodium lamps (e.g., internal ignitor, etc.), consult the lamp manufacturer about whether dimming is allowed and resulting parameters and limitations.

Besides dimming range, NEMA recommends that high-pressure sodium lamps be operated at full light output for at least 15 minutes before dimming. If a voltage interruption extinguishes the lamp, the timer should be reset only after the lamp has restarted. For more information, consult the Guidelines.

Note that dimming some high-pressure sodium lamps and retrofit metal halide lamps can result in changes to color temperature, color rendering and efficacy. NEMA further points out that high-pressure sodium lamps are susceptible to “drop out”—sudden extinguishment—if rapidly dimmed after the lamp operates for about 15,000 hours. Users may confuse this with the lamp having failed; if the user allows the lamp to cool, the lamp will relight and operate at its rated wattage for its rated life in an undimmed mode. To reduce the potential for this, NEMA recommends slowing the dimming rate to about 1.5 minutes from full output to maximum dimmed condition (while maintaining sufficient voltage to sustain the arc).

Metal halide lamp dimming

Dimming is possible with pulse- and probe-start quartz metal halide lamps, pulse-start ceramic metal halide lamps and many types of specialty lamps, such as lamps with internal ignitors or starting aids that operate on probe- and pulse-start metal halide ballasts. NEMA does not recommend dimming for self-extinguishing T-type metal halide lamps and retrofit high-pressure sodium lamps designed to operate on metal halide ballasts.

NEMA recommends that metal halide lamps not be dimmed below 50-70% of lamp power, depending on the lamp type, for the same reason as high-pressure sodium lamps—to dim below recommended levels may degrade lamp life, efficacy, color and lumen maintenance. Below is the recommended dimming range for each type of metal halide lamp, per NEMA:

• 100% to 50% of rated lamp power for probe-start quartz metal halide lamps;
• 100% to 60% of rated lamp power for 150W or smaller pulse-start quartz metal halide lamps;
• 100% to 50% of rated lamp power for >150W pulse-start quartz metal halide lamps;
• 100% to 70% of rated lamp power for <150W ceramic pulse-start metal halide lamps; and • 100% to 60% of rated lamp power for 150W or larger ceramic pulse-start metal halide lamps. For specialty metal halide lamps, consult with the lamp manufacturer about allowable dimming and wattage range. [caption id="attachment_3913" align="alignnone" width="404" caption="Correlated color temperature shift for quartz metal halide lamp across dimming range. Image courtesy of NEMA."]
[/caption]

As with high-pressure sodium lamps, NEMA recommends that metal halide lamps be operated at full light output for at least 15 minutes before dimming. If a voltage interruption extinguishes the lamp, the timer should be reset only after the lamp has restarted. For more information, consult the Guidelines.

Manufacturers limit the operating position of probe-start lamps to the base-up position if the lamp is to be dimmed. Most pulse-start quartz and ceramic metal halide lamps may be dimmed in any operating position, with some exceptions, including ceramic metal halide lamps 150W and larger; consult the lamp manufacturer for specific information about allowable dimming and operating position for the selected lamp type.

Note that metal halide lamps typically experience some degree of color shift during dimming; clear quartz lamps, for example, may exhibit a significant increase in color temperature, with the shift extending to as high as 5000-6000K compared to the typical 3000-4000K. The color shift in a phosphor-coated lamp may be much less pronounced. For example, a 3700K coated lamp may increase to just 4000K during dimming.

Additionally, as with high-pressure sodium lamps, lamp efficacy and color rendering may decline with dimming.
Click to expand...
I've just heard it can change the spectrum if you dim them. But that was some informative shit. Awesome man. I usually get smarter after reading your posts.
 
Wastei

Wastei

Well-Known Member
Renfro said:
Has anyone actually tested this, like in a side by side? Maybe, maybe not. Honestly, who cares. Do what you gotta do and when the bulb no longer puts out get another.

I would think that a dimmed bulb might actually last longer, so long as the arc is stable.
Click to expand...
This is very true. I've always dimmed 600's down to 400w in veg. 600's always last longer.

I guess there's a range and you get worse output and lifespan if dimmed down to low. Never tried to dim down more than 30%. Cheers!
 
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