# is it better to douse the mover lamps ... Say for an hour



## ship (Dec 22, 2009)

Question came up today to douse moving light lamps or not to douse?

What do you do say for lunch break or while working on other parts of the show during design? What's the proper thing to do?

(My three paragraph response will follow later....)


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## photoatdv (Dec 22, 2009)

Nope, not unless you'll not be using them for 3+ hours in general. Also you have to factor in that there's a higher chance of failure striking than in operation, so if it's close to a show you have to consider that. 

Of course, if it's really cold you don't want to douse unless absolutely necessary until the shows over...


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## sstolnack (Dec 24, 2009)

I thought I heard somewhere (maybe it was on CB... I don't remember...) that each time you strike the lamp, it's equal to leaving it on for an hour. (or it subtracts one hour of lamp life, or something, I don't remember the wording...). Is that true?


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## len (Dec 24, 2009)

If I'm not using movers for a while, I'll open the shutters. They'll remain powered and the fans will continue to run. Striking a discharge lamp puts some number of hours of wear on the lamp, so why bother. It's like starting and stopping the engine of a car. There's a line somewhere where the gas savings exceed the cost of the shortened engine life.


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## Chris15 (Dec 25, 2009)

sstolnack said:


> I thought I heard somewhere (maybe it was on CB... I don't remember...) that each time you strike the lamp, it's equal to leaving it on for an hour. (or it subtracts one hour of lamp life, or something, I don't remember the wording...). Is that true?



It was my understanding that it was closer to 2 hours...
Remember also that projector lamps are by and large discharge lamps also and so the same rules apply.

Other comments later...


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## ship (Dec 27, 2009)

Chris15 said:


> It was my understanding that it was closer to 2 hours...
> Remember also that projector lamps are by and large discharge lamps also and so the same rules apply.
> 
> Other comments later...



Ready for a reply from me in my way or cotinuted debate? This is a very important topic debate? 

If of help. a noted LD asked me about it in not knowing for sure himself what was best and I put some study into it for an answer. 

Not persay an hour before a show where you don't want to risk you having to repell down from the grid so as to change a lamp in a fixture that won't strike while the audience is just entering the building at best, more a question of before production/tour rehearsals what at least during lunch break and or in pre-production in focusing on other lights, this concept of dousing or leaving them struck such fixtures that are not for the moment in use could be? This or perhaps in pre-hang fly during the tour of the lights in initially testing them than hours later trusting that they will work again.

Got this tour I have been tracking for the past like year and a half now. I has a few hundred fixtures on it. Should be in tracking the cause of failure of every lamp on the the tour per fixture, be sufficient one would assume to confirm or deny any presented above reason to douse or not to douse them. This amongst other ratioals for to strike or not strike your lights. Still open for debate thought somewhat in my view. Good points to both ends.


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## Chris15 (Jan 7, 2010)

So a suitable amount of time has passed that I'll now expand...

As always, there a number of factors at play, how you weight them will depend on the individual circumstances at play.

A discharge lamp will draw additional current to it's "normal" whilst the lamp is warming up. We're talking a few minutes here. Whether you are paying for power and at what rate will affect the relative weighting of this. (But it is important to consider in say a carbon neutral spruiked gig...)

I would tend to think (and remember here I'm an audio guy and an engineer, not a lighting guy) that you would be far better when not using the lights to leave the shutters fully open and on white, no gobos. Basic premise being the less that's in the optical path, the less there is to stop heat dissipation and heat related stresses. Ergo the fixture runs a little cooler. (And in doing so, contributes a little less to the HVAC load (maybe - not sure on my logic here)...

And then there is the lamp life questions... Only proper way to prove this would be an experiment - comparing lamp life if struck once and then left on until it died versus say res triking every 2 hours or sometrhing with a total count of number of strikes and then a division of the time differential between the two (noting that to be accurate multiple tests would be needed to lessen the variable caused by the individual lamp)...

Interesting discussion point...


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## ship (Jan 7, 2010)

As sent to the LD':

In my opinion, douse the lamps where possible. Might leave them struck during an intermission during a show so as to ensure they will be working for the second act as an option but otherwise where ever possible douse them. (Addition, perhaps if an hour before the show leave them also struck.)


(Opposing view)
Each time you strike the arc on a lamp, it takes a lot of current, takes away some on overall lamp life due to electro-magnetic effects and adds to the percentage chance as the lamp ages that it won’t strike again when needed. 

Those would be benefits of leaving the lamp’s arc struck. (Works for now, leave it struck in it working the show.)



On the other hand 

A (normal arc) lamp designed for 750 hours of operation is tested for 750 hours (use) of one hour on, 15 minutes off and 750 strikes. The more you strike the arc beyond that large amount of strikes to the lamp (hours) you have, the less optimum lamp life you get. 750 Strikes (to the arc) is a lot of strikes to an arc however and I doubt most lamps would see that many before they are well over their rated lamp hours and already dim(snowball). Assuming X amount of lamp hours at a color temperature and luminous output, that extra hour or two at a time does add up both on the lamp hours and Kilowatt hours. Dousing (especially during design/rehearsals or not important say load in time) would also be much greener for the environment on power and heating/cooling costs. Likely the amount of extra current needed to strike the arc is much less overall than the Kilowatt hours needed to maintain the arc while not in use.



The dimming of an arc lamp in sleep mode even when optimum say on a Mac 2K fixture also doesn’t boost lamp life, it just reduces heat & power consumption.

Add to that, some fixtures don’t have very good cooling or ECG dimmed modes for use when shutters closed / sleeping, this tends to overheat lamps and fixture parts. Shutters are closed and the lamp is on at full power. This overheating wears out fixture parts and overheat lamps in shortening their life if left on – gets to become really expensive on some types of fixture to leave them burn. VL-3K fixtures would especially benefit from dousing them instead of leaving them burn. 

(A good arguement in what works don't chance it to not working, but in going "Greener" in our industry and or just plain saving the costs of electricity and lamps I would in having researched such a thing recommend dousing the mover lamps were possible. This especially for those fixtures that don't dim the lamps and run at full output in shutters closed when not in use. 

My answer - douse them when possible.)





See Section 7.4 to 8.1 Technology and Application – Metal Halide Lamps Photo Optics, Osram Sylvania 2000.


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## Chris15 (Jan 7, 2010)

The other argument in the enviromental debate is that the reduced lamp life accorded by restriking leads to a faster turnover of lamps and thus more lamps to be disposed of, complete with Mercury and other "hazardous wastes".

This is also part of the compact fluoro debate that is often neglected...


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## ship (Jan 7, 2010)

I can provide proof on the percentage of no-strike lamps verses those that failed early due to over heating and lots of other proof to back this up. Been tracking one show for almost a year now, another show for almost two years now and have such raw data I can pull together in proving both the point of some fixtures are worse than others and dousing for especially the other fixtures would be a good thing.

Don't know on the production side by way of like an hour or two so as to seat the audience in having an option B design plot given a few fixtures won't re-strike verses what amount of fixtures will die off due to over heating during the show. I'm fairly certain its a balance though. On the other hand, if not a few $100 per ticket... douse them lamps and if they don't strike design around or change the lamp.

Douse them lamps when ever possible especially if during a lunch break or load in. This is greener and cheper overall in cost effectiveness.

(On request I will provide such data).


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## ship (Jan 7, 2010)

Chris15 said:


> The other argument in the enviromental debate is that the reduced lamp life accorded by restriking leads to a faster turnover of lamps and thus more lamps to be disposed of, complete with Mercury and other "hazardous wastes".
> 
> This is also part of the compact fluoro debate that is often neglected...




As said, 1hr on, 15min. off if rated for 750hr a lamp is rated for and that's a warranty of the lamp type of thing if it doesn't do so in up to 2/3 of it's rated lamp life. I doubt if any lamp would ever have up to those amount of 750 lamp strikes given a show in use is what at least two hours? 

Movng light fixtures now indeed need to track not only lamp hours but also strikes and burst mode minutes for warranty purposes as otherwise it does make it difficult to return bad lamp or make for a statement in design for the fixture problems. Just had a moving light fixture maker reject my request for sending back some bad warranty lamps. They said the lamps that were sent with the fixtures with my full tracking of the lamps were over a year old.... sorry.. your fixtures were not used much by us given most designers didn't request them for use and thus they over the past year in lamps failing due to fixture or lamp problem, such a problem was not noted before now but are valid warranty lamp claims. (So if you won't take back the lamps that come with your fixtures... this Spring what's the price of your fixtures without lamps installed in them in you now having to remove the lamps and I'll provide them no doubt cheaper? Yes we will do this if you won't represent as lamp distributer the lamps you represent for normal warranty purposes of the lamp hours over the fixture age. And if not... perhaps a different brand of fixture will work better for our needs.)

Next year should we buy fixtures form that manufacturer expect we won't be paying for lamps in the fixtures already installed in them. Screw you, don't follow normal polcies of bad lamps due to bad lamp to bad design for fixture in me at times both sending back base for lamp and lamp together in the same box = what's up for this in first lamp installed in the fixture and I want a refund on both. That manufacturer can spend extra time in pulling the lamps from their fixtures and us providing our own from suppliers that will represent their lamps for warranty purposes after manufacturer evaluation of the cause of the failure. Best way to get an upgrade from a lamp or fixture is to send them back when they fail before expeced lamp life or 2/3 of that at least. 1.2KW Fast Fit lamps at least took such stress on their lamps and fixtures at least in upgrade or improvement.

So overall as a concept, if the lamp is rated for even if 3,000 hours given this now 3,000 arc strikes, its doubtful one would ever strike and douse the lamp that amount of times overthe life of the lamp. Opposing side the the douse or leave struck arguement I did study into and for me it would seem nonfounded in concern.

You go over the 3,000 strikes or even if high output norm of 750 lamp hours thus 750 strikes and get less than say 500 lamp hours - send that lamp back and be suspect to the fixture problem if sestemic over time verses lamp problem in no upgrade to the lamp in lasting longer. Modern fixtures often have problems such as the VL-3K or Mac2K XB in adjusting.

Overall concept still, douse them arc's where possible.

On recycling, your supplier of lamps often will take on the small scale your mover lamps back for free. Get past this, most clean up companies or lamp recyclers verses lamp manufacturers also have recycling available - heck even Feit recycles. I'm up to like two 55gal drums full of moving light lamp or sports lightler or shop lighting lamp recycling per year. This in addition to two drums of fluorescent, two of incandescent etc. including various batteries, computer circuit boards, computer monitors, capacators, transformers etc. Few thousand dollars to recycle per year. Mostly moving light lamps are more costly to recycle due to their rare earth elements. Just a thing you gotta live with in me using a kittie litter container for a say week or three temporary storage for the amount of lamps I inspect per week. Such a size of container to recycle should be sufficient for most and not cost over $1K to get rid of.

Beyond that, want my end of year bonus reflection of my fight against the terriff against importion of moving light lamps given it's based on the proper disposal of them. Given I do so and pay extra for it, we should not pay that terriff per lamp charged or it should get refunded given I have records indicating I was sort of double taxed on such lamps so as to buy and properly dispose of and given I did so was also taxed as it were.

I.E. lamps not grey marketed from Europe get this tax on them for recycling purposes. You properly recycle them and pay for that in doing so you are perhaps double taxed on for doing so if you really do pay for proper recycling. That's a problem I have never found a way around dealing with.


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