# Relamping HID (MV & MH)



## dspiffy (Nov 25, 2013)

Got into a . . . discussion with another guy a few days ago.

Have you, or have you ever known anyone, to use metal halide lamps (bulbs) in mercury vapor fixtures, or vice versa?

It will work in most cases, the question is whether it is normal to swap lamps.


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## Slay301 (Apr 23, 2018)

It’s normal to swap both to LED lol


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## backstay (Feb 3, 2011)

dspiffy said:


> Got into a . . . discussion with another guy a few days ago.
> 
> Have you, or have you ever known anyone, to use metal halide lamps (bulbs) in mercury vapor fixtures, or vice versa?
> 
> It will work in most cases, the question is whether it is normal to swap lamps.


I would think lamp longevity would be impacted.


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## u2slow (Jan 2, 2014)

I thought I read/heard something about newer lamps and ballasts may be suitable for both applications. Or it was a universal re-ballast/ignitor kit. Something to check into...

Now you either gut the fixture for a screw-in LED, or hang up one of those ufo-style highbays instead.


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## joe-nwt (Mar 28, 2019)

Do you have code that allows a lamp to be installed in a fixture it is not approved for? Or do you have a fixture marked for operation with either lamp?

Or is all this "hypothetical"?


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## Almost Retired (Sep 14, 2021)

at one time we could get "multi-vapor" bulbs. MV, HPS, MH; worked for all of them. but yes bulb life was much shorter


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## dspiffy (Nov 25, 2013)

My understanding is that MV will behave similarly in both MV and MH fixtures. Putting MH in an MV fixture the ballast will run hotter and it will sometimes have difficulty starting in cold temperatures.

I have not seen or heard anything about bulb life.


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## paulengr (Oct 8, 2017)

MH IS a MV lamp but with an outer bulb with the magic gases. But yes the ballasts are different. By the time you pay for ballast and bulb, may as well get a Holothane LED fixture and be done changing anything for years,


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## kb1jb1 (Nov 11, 2017)

When replacing PSMH hi bays with the " equivalent " LED, does anybody do a survey with a light meter ( with new PSMH lamps) before the change out? I find that the recommended LED replacement has a reduced foot candle level at the work plane. 
We talked about life expectancy with LED hi bays on another thread. I sometimes wonder if it is worth changing to LEDs if the existing fixtures are good.


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## Forge Boyz (Nov 7, 2014)

kb1jb1 said:


> When replacing PSMH hi bays with the " equivalent " LED, does anybody do a survey with a light meter ( with new PSMH lamps) before the change out? I find that the recommended LED replacement has a reduced foot candle level at the work plane.
> 
> This all depends on what size replacement fixtures are used. I have found that a fixture in the low 20K lumens is a great replacement for a 400W MH. You learn what works after a while and can not always trust what the LED manufacturers claim is an equivalent.
> 
> ...




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## VELOCI3 (Aug 15, 2019)

kb1jb1 said:


> When replacing PSMH hi bays with the " equivalent " LED, does anybody do a survey with a light meter ( with new PSMH lamps) before the change out? I find that the recommended LED replacement has a reduced foot candle level at the work plane.
> We talked about life expectancy with LED hi bays on another thread. I sometimes wonder if it is worth changing to LEDs if the existing fixtures are good.


Just look at the specs. The manuf usually recommends LEDs at half the lumen output. Plus the fixture optics are designed for a mono point source. They like to say you don’t need as much light if you have a higher CRI value. 


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## dspiffy (Nov 25, 2013)

I have seen guys relamp MH into MV fixtures and assumed it was normal. I mentioned this and a guy said he'd never seen it done and that does not happen.

Seems like my experience is the outlier.

As for LED conversions . . . for what it's worth, the largest building I've done is around 50k square feet commercial. Most of my jobs have been smaller. BUT.

My experience has been, if you are happy with the light quality and have no other reason to change the fixtures, you are better off leaving well enough alone. If you have other reasons to upgrade, or are remodeling, obviously LEDs are the way to go.

I've had guys pay me to switch from T12 to T8 to LED in a 2 pay shop. They spent way more than they saved, and the T8s honestly had the best light output in their situation. The energy savings wasnt much either.


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## kb1jb1 (Nov 11, 2017)

VELOCI3 said:


> Just look at the specs. The manuf usually recommends LEDs at half the lumen output. Plus the fixture optics are designed for a mono point source. They like to say you don’t need as much light if you have a higher CRI value.
> 
> 
> Sent from my iPhone using Tapatalk


I understand the mono point idea but I think the PSMH has a better broadcast of light on the ground or work plane. I look at the street lights they put up and now the intersections look darker. An oxymoron. They look brighter but the area is darker.. Some places they are replacing the LEDs with a much higher lumen one. Obviously a much more expensive one.


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## MotoGP1199 (Aug 11, 2014)

dspiffy said:


> I have seen guys relamp MH into MV fixtures and assumed it was normal. I mentioned this and a guy said he'd never seen it done and that does not happen.
> 
> Seems like my experience is the outlier.
> 
> ...


I just wired up two pool heaters that cost (installed) over $100,000 that replaced two working pool heaters (2 years old) to go from 87% efficiency to 95%. These run on natural gas that is super cheap and heat one city swimming pool. One heater is a backup.

They will not recover the cost savings before they need new heaters. Leaving well enough alone would have been the wiser option for saving money and probably better for the environment than tossing perfectly good heaters away. Oh well, tax payer money.


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## nrp3 (Jan 24, 2009)

When I replaced the MH high bays in my customers hangar with LED, the customer just chose the highest output ones he could get in a 2 by 4 fixture and it turned out great. Instant on was one of the things they like best. Brighter in there than it ever was. Cost really wasn't an issue and while there may have been some energy savings, renting the lift and pushing all the aircraft in and out was a hassle. Lost one driver in three years and had a lift in while doing security cameras. Seller sent new complete fixture. I kept the old and will swap out the bad driver eventually.


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## splatz (May 23, 2015)

kb1jb1 said:


> When replacing PSMH hi bays with the " equivalent " LED, does anybody do a survey with a light meter ( with new PSMH lamps) before the change out? I find that the recommended LED replacement has a reduced foot candle level at the work plane. We talked about life expectancy with LED hi bays on another thread. I sometimes wonder if it is worth changing to LEDs if the existing fixtures are good.





kb1jb1 said:


> I understand the mono point idea but I think the PSMH has a better broadcast of light on the ground or work plane. I look at the street lights they put up and now the intersections look darker. An oxymoron. *They look brighter but the area is darker*.. Some places they are replacing the LEDs with a much higher lumen one. Obviously a much more expensive one.


I think the initial impression is a big thing with LEDs, they look so bright, but if you look at it with a meter, and actually work in the area before and after, it's not a slam dunk.


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## paulengr (Oct 8, 2017)

splatz said:


> I think the initial impression is a big thing with LEDs, they look so bright, but if you look at it with a meter, and actually work in the area before and after, it's not a slam dunk.


It’s more complicated with LEDs. Let’s put it this way. Say I have a customer that wants to redo a warehouse and wants the most efficient lighting possible. As long as I meet minimum average FC requirements he just wants the lowest wattage possible. At almost 300 lumens per Watt then my choice is clear. I just put up high pressure sodium high bays as high as possible spaced so that the AVERAGE FC meets the minimum. Now this will be the most efficient system possible but it’s going to be like a parking garage…it will be almost the same as working in a moonless night sky!

We are in an era of endless flexibility and options with lighting which puts more work on the EC to get it right.

LEDs have higher efficacy. A “white” LED isn’t actually “white”. An LED can be any color of the rainbow but white isn’t in a rainbow. It is a blue LED. It is covered in phosphor just like fluorescent bulbs. The most “efficient” (lumens per watt) are the ones closer to blue or cool white. The most efficient in terms of best for how you see are closer to “daylight” and include more yellow phosphor at the expense of efficiency. So pay attention to the color not just lumens.

All discharge lighting (MH, MV, HPS, and even fluorescent) outputs unidirectional light in all directions. We have to use reflectors to capture some and it bleeds all over. This leads to two things. For one glare is much higher. For two you get a lot of spillover because of reflector efficiency. In contrast LEDs emit light all in one direction with roughly a 120 degree beam spread. A simple lense directs it anywhere you want highly efficiently. There is very little spillover and very little glare. But you can get light/dark spots and dark areas not intentionally lit. And whatever you do, don’t buy corn cobs. This is the least efficient way of using an LED and the MH and Fluorescent bulbs are much better than corn cobs.

So in the past we just put up arrays of lights and figured things on lumens per square foot or more often watts per square foot. If you just apply LEDs at say 20-50 FC you will blast people out of the area. If you just put a row down a sidewalk and expect to illuminate the yard on either side, think again. You need to plan not only light output but evenness. And you need to put light where you want it, not just rely on spill over. You really have to outright rethink how you do lighting with LED. This isn’t like switching from HID to T-5HO where we just change fixture spacing. You really have to rethink lighting.

Fortunately the lighting companies know that. They have lighting engineers and software that can plan new layouts for you basically for free. I’ve done a lot of engineered lighting layouts. What I found happened is that I used fewer and cheaper fixtures and had as good or better lighting than the original,

And all this being said lighting manufacturers tend to lie a lot. There are big problems with their lumen claims in particular. Established vendors like Cooper are doing better but it can still be a problem especially if you troll the internet.

Finally if you are doing this for efficiency and you already have fluorescent or MH and it’s all working think again!!! Watt for Watt LED CAN be more efficient but good fluorescent and MH systems are so efficient it never pays for itself. There is money to be saved in new construction or replacing an entire system that has been neglected and the result (if designed properly) can be much better but you can screw it up too.


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## dspiffy (Nov 25, 2013)

splatz said:


> I think the initial impression is a big thing with LEDs, they look so bright, but if you look at it with a meter, and actually work in the area before and after, it's not a slam dunk.


I've had the opposite issue. One time I did a full relamping of incandescent and CFL to LED. The LEDs were more lumens, but less glare, so the business owner insisted they were dimmer. Meanwhile the property owner, not the business owner, had hired me to do the relamping. Turned into a huge debacle and I never got paid for that job.


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## kb1jb1 (Nov 11, 2017)

nrp3 said:


> When I replaced the MH high bays in my customers hangar with LED, the customer just chose the highest output ones he could get in a 2 by 4 fixture and it turned out great. Instant on was one of the things they like best. Brighter in there than it ever was. Cost really wasn't an issue and while there may have been some energy savings, renting the lift and pushing all the aircraft in and out was a hassle. Lost one driver in three years and had a lift in while doing security cameras. Seller sent new complete fixture. I kept the old and will swap out the bad driver eventually.


Instant on I think is the biggest seller for LED lights.


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## u2slow (Jan 2, 2014)

kb1jb1 said:


> I sometimes wonder if it is worth changing to LEDs if the existing fixtures are good.


Gauge your customer. Some have energy grants/budgets to blow. Some are happy to have the their few dead lights fixed. Others never figure out they're killing their MHs with their own bad habits.

I find LED stuff really hit or miss.... lots of miss. The light quality I like best for low-bay and closer-proximity is T8 fluorescent with electronic ballasts.


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## Forge Boyz (Nov 7, 2014)

paulengr said:


> Finally if you are doing this for efficiency and you already have fluorescent or MH and it’s all working think again!!! Watt for Watt LED CAN be more efficient but good fluorescent and MH systems are so efficient it never pays for itself. There is money to be saved in new construction or replacing an entire system that has been neglected and the result (if designed properly) can be much better but you can screw it up too.


I have found it to be the other way, at least with MH. Case study: A welding shop with horrible reflectance. The back half of the shop had 400W MH. We relamped it at one point, which brightened it up considerably. About 2 years later we changed out the lights to 150W LED UFO's, 5000K and about 24,000 Lumens. It is definitely better lit, and payback is at about 2 -3 years. 

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## aidonius (Jul 10, 2018)

kb1jb1 said:


> I understand the mono point idea but I think the PSMH has a better broadcast of light on the ground or work plane. I look at the street lights they put up and now the intersections look darker. An oxymoron. They look brighter but the area is darker.. Some places they are replacing the LEDs with a much higher lumen one. Obviously a much more expensive one.


One of the big considerations at least around here is that they only want specific areas lit up which often makes it look like it's darker because the total area lit is noticeably smaller compared to before. 
They figured out a while ago that light pollution is bad for the birds and the bunnies and so on in a variety of ways that are consequential to human activities. Apparently more recently they have learned that it has health impacts beyond keeping people awake(which is a big problem in itself).


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## Norcal (Mar 22, 2007)

A bit late but MV lamps will work on most MH ballasts, but MH does not normally work on MV ballasts both being the same wattage lamps.


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## kb1jb1 (Nov 11, 2017)

Norcal said:


> A bit late but MV lamps will work on most MH ballasts, but MH does not normally work on MV ballasts both being the same wattage lamps.


MV is that mercury vapor or multi vapor?


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## kbatku (Oct 18, 2011)

One thing I mentioned in an earlier thread that I've just discovered is that if you use silicone sealant in LED wall packs it degrades the leds and drastically shortens their life. My experience with LED's is that there are wild variation in quality and construction that significantly impact their longevity. The LED MAY last for "50,000 hours" but depending on the design , construction and driver this "50,000 hours" may work out to a year or two and the supposed savings from longevity disappears.


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## dspiffy (Nov 25, 2013)

I've decided my philosophy on LEDs is as follows:

When you remodel or replace, go LED.

If everything else is staying the same, go LED when it fails. 

I'm done changing out perfectly good fixtures for LED fixtures that fail in a couple years.


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