Author Topic: Running 100 watt mercury lamps  (Read 1901 times)
RadiantMV
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Running 100 watt mercury lamps « on: December 20, 2022, 11:54:37 AM » Author: RadiantMV
Since the H38 ballasts are getting harder to find, would it be possible to run a 100 watt mercury lamp on an M90 pulse start metal halide ballast with ignitor removed?
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Medved
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Re: Running 100 watt mercury lamps « Reply #1 on: December 20, 2022, 01:09:46 PM » Author: Medved
M90 (100W MH) will overdrive the lamp, better is to use M98 (70W MH). Of course, ignitor removed/deactivated...
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sol
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Re: Running 100 watt mercury lamps « Reply #2 on: December 20, 2022, 01:11:18 PM » Author: sol
I believe a de-ignitored M98 70w MH ballast is a better option. The unofficial rule is that a low wattage mercury vapour lamp can work close to spec on the next wattage down metal halide with the ignitor deactivated or removed.

I have been running a 75W mercury vapour lamp on a 50W metal halide ballast with no ignitor on dusk to midnight service for about three years now and it is still very bright.
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Lumex120
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Re: Running 100 watt mercury lamps « Reply #3 on: December 20, 2022, 01:22:39 PM » Author: Lumex120
A 70w/M98 ballast is best for running 100w mercury lamps. It will very slightly underdrive them (not to the point of even being noticeable) which in the long run should actually extend the lamp life a bit. Like other said though, make sure the ignitor is disconnected or removed though.
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RadiantMV
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Re: Running 100 watt mercury lamps « Reply #4 on: December 20, 2022, 02:01:37 PM » Author: RadiantMV
I believe a de-ignitored M98 70w MH ballast is a better option. The unofficial rule is that a low wattage mercury vapour lamp can work close to spec on the next wattage down metal halide with the ignitor deactivated or removed.

I have been running a 75W mercury vapour lamp on a 50W metal halide ballast with no ignitor on dusk to midnight service for about three years now and it is still very bright.

By that logic, would the 100 watt ballast be good with a 125 watt mercury lamp? I know the rule for sure ends at 175 watt where the ballasts are interchangeable.
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joseph_125
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Re: Running 100 watt mercury lamps « Reply #5 on: December 20, 2022, 02:05:30 PM » Author: joseph_125
I generally run my 125w MV lamps on a 100w PSMH ballast without ignitor. Apparently there's a 125w PSMH ballast that's even better but I find 100w works reasonably well.
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Medved
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Re: Running 100 watt mercury lamps « Reply #6 on: December 21, 2022, 03:05:38 AM » Author: Medved
I know the rule for sure ends at 175 watt where the ballasts are interchangeable.

When speaking about pulse start MH, not yet. The MV175W is more closer to 150W MH (both ~1.8A). On 250W (~2.1A MV, ~2.9A MH) you will struggle to find a corresponding ballast, at 400W there is even bigger mess: MH lamps are made in both specs, 3.2A (corresponding to the 400W MV) as well as the 4.4A (the spec originating from European HPS), so you have to be sure which you ere dealing with. But if you accept a bit underdrive (affe ts practivally just the otput and efficacy), you may still operate a 250W MV on a 150W MH (or S56 HPS, by the way, beside the ignition voltage they are electrically the same) and the 400W MV on a 250W MH.

With probe stsrt MH ballasts the compatibility is direct for the same wattage MV, no ballast modifications.
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Re: Running 100 watt mercury lamps « Reply #7 on: December 21, 2022, 03:20:13 AM » Author: joseph_125
I think the rule generally ended at 175w and higher since a better alternative already existed for 175w-1000w MV lamps, the probe start MH ballast which didn't require circuit modifications and was more straightforward in terms of ballast wattage and lamp wattage pairing. Because of this, most collectors never really looked into the viability of pulse start MH ballasts for those wattages.
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Re: Running 100 watt mercury lamps « Reply #8 on: December 21, 2022, 08:50:14 AM » Author: LightBulbFun
When speaking about pulse start MH, not yet. The MV175W is more closer to 150W MH (both ~1.8A). On 250W (~2.1A MV, ~2.9A MH) you will struggle to find a corresponding ballast, at 400W there is even bigger mess: MH lamps are made in both specs, 3.2A (corresponding to the 400W MV) as well as the 4.4A (the spec originating from European HPS), so you have to be sure which you ere dealing with. But if you accept a bit underdrive (affe ts practivally just the otput and efficacy), you may still operate a 250W MV on a 150W MH (or S56 HPS, by the way, beside the ignition voltage they are electrically the same) and the 400W MV on a 250W MH.

With probe stsrt MH ballasts the compatibility is direct for the same wattage MV, no ballast modifications.

its not quite that simply sadly!


most US Metal halide pulse start ballasts have the exact same electrical characteristics as their probe start counterparts just with a lower OCV and an ignitor (since the OCV is no lower required to actually also strike the lamp it can be lowered and a more efficient ballast made)


and even in Europe there exists pulse start metal halide lamps in "MV" spec not just SON spec, its one of the fun things about metal halide lamps, is for a lot of wattage ranges, there is no such thing as a metal halide ballast, because there where always some lamps made to run on HPS gear and some made to run on MV gear, even from within the same manufacturer you would get lamps of the same wattage for the 2 different specs

but this is only something us people in 50hz land have to worry about


in the US for higher wattage lamps you can generally take a PSMH ballast disabled the ignitor and run an equivlent mercury lamp, the only thing to watch out for is I do know there are PSMH ballasts for the FC2 250W double ended metal halide lamp, which is HPS spec!
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RadiantMV
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Re: Running 100 watt mercury lamps « Reply #9 on: December 21, 2022, 08:31:08 PM » Author: RadiantMV
Since we are on the topic, what kind of ballast would be suitable for running a European 80 watt mercury lamp in North America? Assuming the 75 watt H43 ballast has different specs, i wonder if a PSMH one could do the job.
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Re: Running 100 watt mercury lamps « Reply #10 on: December 21, 2022, 11:30:28 PM » Author: LightBulbFun
a 100W CWA H38 ballast should do just fine for an 80W mercury lamp, has to be CWA however, not HX, as only CWA is constant current

an 80W mercury lamp runs at 115V 0.8A a 100W mercury lamp runs at 130V 0.8A, and CWA ballasts are not super fussy about lamp arc voltage and are pretty good constant current drivers

that is no matter how the lamp voltage fluctuates they will keep the current the same

with a HX ballast the lower arc voltage would cause an increase in lamp current, overdriving both the lamp and ballast)

otherwise if you dont have a 100W CWA H38 ballast a left field approach would be a single lamp rated F72T12/F96T2 HO ballast and just stick the lamp between 1 red and 1 blue wire :) again these ballasts tend to be pretty constant current, its how many are able to drive multiple sizes of HO lamp, since to a fair degree, they dont care for lamp arc voltage, and a HO tube runs at 800Ma just like an 80W mercury lamp!


there is no real good PSMH ballast for driving an 80W mercury lamp and indeed a H43 75W mercury lamp runs at 130V 0.6A
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joseph_125
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Re: Running 100 watt mercury lamps « Reply #11 on: December 21, 2022, 11:42:58 PM » Author: joseph_125
Interesting, I've got both so I might give that a try with a modern 80w lamp and if that works I can finally light that 1950s 80w Philips HPL safely. I've had it for a few years and never lit it up.

The HO ballasts also work nicely to drive a pair of 100w MV lamps. I've tried that before but I never tried running a single MV. I suppose mine can run a single MV lamp since they're designed for either one or two lamps.
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Lightingguy1994
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Re: Running 100 watt mercury lamps « Reply #12 on: December 22, 2022, 01:44:01 AM » Author: Lightingguy1994
Good thread for my question since we're on the subject here.

I intend to use the 39w magnetic PSMH ballasts with 40/50w mv lamps and my 75w mv lamps with the 50w PSMH ballast.

I'm wondering though, since its easier to find the 50w PSMH ballasts, just how much overdrive will one do to a 50w mv lamp. And if I accept shorter life, is that acceptable otherwise to run?
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Medved
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Re: Running 100 watt mercury lamps « Reply #13 on: December 22, 2022, 10:04:43 AM » Author: Medved
The 50W MV is a 0.6A lamp, 50WMH is 0.75A, so with the higher MV voltage I would expect around 0.7A, so about 60W.
With the small wattages (below 100W) I would better not overdrive them, they are already quite tight on the thermal budget (they need rather high pressure to keep the arc loading within reasonable levels at that low current).
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Lightingguy1994
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Re: Running 100 watt mercury lamps « Reply #14 on: December 22, 2022, 02:39:04 PM » Author: Lightingguy1994
i dont suppose theres a way to knock the current down a notch.. ? such as lower than 120v going in, maybe 100 to 110?
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