Conventional Fixtures Lamp life after extended closure?

gafftaper

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This is mostly a question for @DELO72 and @ship, but you are all welcome to answer. I'm curious if there is any data on what happens to lamp life after an extended shut down? If your incandescent lights haven't been on for a year and a half does it shorten lamp life or will the lamp life clock just start ticking again as originally expected?

Thanks!
 
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DrewE

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I can't think of any reason why one hour downtime would be any different than one year or one decade. A strip of metal hermitically sealed in a glass ampule isn't going to undergo any spontaneous degradation to speak of. (The same reasoning would apply to apply to gas discharge arc lamps, too.)

I've never seen a "best if used by" date on light bulbs, nor do I expect to.
 

JohnD

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Since the fixtures aren't sealed, I wonder if dust and cobwebs and such will stink up the joint the first time they are fired up?
 

ship

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Inspection, blow out and cleaning probably not a bad thing after a period of shut down. John D. has a good point. Even if not used for a year, every year you do maintenance on inventory to clean lenses, check lamps, etc. Was this done? (Clean the filters etc. in your dimmer room also.)

Were they hung near moisture or air conditioning while not in use which will be a little different after a year of lack of use than just a few weeks or even months between usage.

Are we sure the lamps were practically new? Remember if your dimmers were not turned or breakered off during this period.... for a year now the filament has still been getting a "warming current" which after a year would eat into lamp hours some. That could be enough to wear down the lamp hours of a more used lamp especially after the first time going to full after warming all this time.

Possible as a theory after a year of warming current in not going full even once a week, the halogen cycle has not over that year refreshed itself at any time in re-depositing tungsten on the filament. So you were instead burning normal incandescent lamps at a low wattage in weakening the filament in later turning them on. This damage or failure does not have to be after the first time turning them on, just as below dirty lamps doesn't persay destroy the lamp after only a few hours.

If your lamp base were bad in now suddenly starting again at getting full voltage current, because the warming current was too high of resistance to get thru the corrosion of the base all last year, that could make a lamp go bad. Kind of like the krackle of a cheap lighting switch when turned onto a full load under heavy load. This could be too much for a filament. This bad light switch takes time to go bad in crackling it's way there especially if that resistance to current flow due to the arching of the base resistance to current flow has been just low enough over the past year to "turn on" once in a while thru the year in further damaging that contact until you used the lamp is at full again. First thing to blow will be this filament as normal with a bad base over time. Story about me tracking bad moving light lamp bases to about 100hr less in lamp life per perfectly good lamp installed in a bad or getting worse base. Over a year of the warming current going on and off from resistance, this could progressively make the base worse than you last saw it. Until instead of 10 volts to the lamp, it's now 120v and the filament might not instantly blow... but... Just another theory.

If the wattage high with a bad base especially, say 1Kw or more and it could cause a spike "On" over what a filament could take at a certain age during trickle or added to that bad base..

Are we sure the lamps were cleaned when installed? A couple of rehearsals often is not long enough for a fingered lamp to blow. But back to the trickle voltage above, who knows what the oils or dirts from a dirty lamp could do to the quartz after a year of the dirt or oil not getting warm enough from warming current on a lamp to cause normal reflection or attraction of the filament towards or away from it.

Were the lamps bench focused properly? I hate it when I'm bench focusing and I get the "Crack" from hitting the reflector. But if the pinch or even globe of a lamp is touching with light pressure on the reflector... could take some time for that to fail - perhaps a year?

Take some photos. This year dark is probably going to be a new thing not really studied in some of the obvious failures shown in photos might have had more than one cause.

Yes, while not studied or specified, the filament can sag some or weaken over time due to gravity - but we are talking 10 to 20 years or more. Never buy a "old" stock used filament lamp on - line. I had more than one filament not survive transport. In my case, lamps from say the 1920's with large long even if supported filaments. Modern compact filaments shuld have much less of a problem.
 

ship

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If you believe your lamps failed due to a manufacturer defect, or want to find out what otherwise caused the failure.

Inspection by you as to the cause of the failure on site is the quickest way to rule stuff like above out and possibly find the problem. Let us know as it's perhaps a unique problem from Covid others might see.

A long time ago I consulted Mark and his lamp engineers about the question of filament sag over a long time on some of my resale stock 20 year old or older ANSI lamps. Wasn't studied persay, but I believe the answer was gravity will probably effect the filament especially when larger and or longer. Kind of like the bug screen on a screen door - it's going to sag at the bottom some, especially given the filament hangers are not like spline on that screen door holding it tight and fixed to the frame. A filament is a spring, normally not a cross weaved screen helping to support against sag. But this would take years even for high wattage large filaments. Your 500w T-3 RSC Based yellow work light filament you will likely see sag on after a few years especially if you do not use it much.

For personal training in looking at what to look at on the failed lamps...
Osram on their lamp speciation page used to have a very excellent manual on lamps which at a high school leve goes all aspects of a halogen lamp including into some causes of failure (Not extensive enough.) You would have go onto say a lamp such as HPL details. Than go to their further information and click on the free PDF file about halogen lamps. I don't have it's name here, I'm out of town on an install. The manual is an excellent education on lamps I have read it many times as with other manuals and guides. GE "Spectrum" manuals used to have a lot of info but are long gone. Ushio for instance used to have "Dr. Bulb." If the Osram guide not on the website and PM Mark directly, he might be able to send you a copy of the PDF. I might also have a copy on my work computer.

Photo's on this website would be the next quickest way to cross out the easy cause of blowing. Photo of fixture, where lamp was, lamp base and detail photos of lamp and base could be looked at by the many experts on lamps on the website.

Finally, if they were new lamps and failed before the expected lamp life, they should still be warranty for 2/3 or 50% expected lamp life dependent on manufacturer warranty.
Some suppliers will have their own warranty terms - say a few months after "purchase date." They might have a or you could ask for a Covid exception to these terms.

If the supplier won't credit these lamps - (some will instantly without sending back to the manufacturer), some suppliers will later credit you for the lamps after sending them back to the manufacturer for inspection and manufacturer of fault. (It costs money and time to send the lamps in but can solve a problem.) If the supplier won't take the lamps back, you can contact your lamp manufacturer for their own warranty perhaps return. You might have to pay for this and most lamps are not made in the US, but it might spark enough interest in them paying shipping should this become an interesting "Covid" problem with lamps they need to get pro-active about with the manufacturers.

Say a warning to schools.... clean your dimmers and fixtures and inspect the lamps before attempting to power up with them again afresh this year etc. If your fixtures were powered up in warming current for a year now without ever bringing up to full to replentish the even if low voltage spent tungsten.... perhaps power the lights up to 20% for an hour and progress to... over a few hours before attempting to use them at "Full". I'm sure ETC is all about this in warnings of this theoretical problem. Or if not.... perhaps a PR warning campaign about cleaning etc. before powering up might be needed to be sparked by your noting this.

A few years ago I met most of the Osram lamp inspection engineer bosses, and met over the phone most of the Philips lamp engineer bosses. They are all very very smart - they are engineers who inspect lamps for a living as opposed to me part time as it were. Just as I in having inspected a few thousand Mac 2K lamps over the years, I was able to tell from looking at a lamp how many hours it had been used within a hundred hours of it's fixture stated usage. That's really good in looking at an arc lamp and telling how many hours it was in use - this say plus 100 hours if the ballast or lamp base had a problem. The more I saw moving light lamps of a type, the closer I could get to this estimation of lamp life and cause of failure on any other type of moving light lamp.

This past week I saw some failed lamps which got rained on. Oh' that explains a lot.

If you return a lamp to the factory for inspection, it might take a while for it to get inspected. And you might or might not get a warranty refund for the lamp. It will also cost a lot of money to inspect the lamp by way of shipping and man/hours to inspect. Might even cause more R&D expense to figure out where the problem is coming from in working with the fixture manufacturer.

On the other hand, you find the answer to your problem eventually, and at times you might make huge changes to solve a problem.

Covid lamp problems just might become something new to study.
 

cbrandt

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I can tell you anecdotally from deep storage of old incandescent stock in a rental inventory, we don't see many failures even when we bring the ancient stuff back out. As @ship said, clean it appropriately. I've still got par 56 lamps from the 90s that don't have any issues when we bring them out. We just don't bring them out often.
 
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gafftaper

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Thanks @ship ! As usual, you bring us a masters class full of information! I'm gonna go through and clean my dimmer racks and fixtures again (I did them last year, but they've been sitting so yeah, best to do it again).
 

ship

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Fair enough point about PAR lamps.
On a par lamp given the halogen or incandescent filament capsule is somewhate small and sealed within the outer lamp capsule with inner and outer pressure capsules not thought about for stability... Short filaments and not much to worry about past say 20 years. I have some HRG 600w and 1.2Kw PAR 64 lamps on the shelves should anyone want to go to "11" in output. They should be fine in sitting on the shelf and me not rotating for gravity. Above was not in considering PAR lamps for cleaning or worry.

For PAR's, perhaps propose a normal wiping of the lens should be done as with perhaps normal yearly PAR testing of the lamp socket with + addition. If a "EXEP or more properly called a GX 16d lamp socket base... The drop test. Will that lamp socket support the PAR lamp with a light bump by you? Added to that standard test... if you can with a pull remove the lamp. If a hard tug on that lamp to remove it from the base... it's probably also bad.

The trickle charge theory in further arching will still be a question to look at for PAR lamps. Filament sag perhaps not as much as problems with the halogen effect not being refreshed at low voltage sustaining current for a year. PAR 64 Halogen lamp say run for a year at 10 volts without the "halogen effect" happening to any spent tungsten. This especially if given a bad base to the lamp, only at times that warming current was running until it stopped. The warming current was in arching to a lamp socket, too resistant to current flow. Once a year later 120v broke thru this resistance to current flow.... How long does this PAR lamp last also given the above problem?

Again I'm only presenting some theories to study.
 

ship

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Drew E and Cbrandit's observations are very important to any theories of "too many words" I responded with to consider. It's a forum and on something like this with two basic concepts, both are important. I think agreed that it's - no after a year or perhaps 20 or more years, no need for a "Used by date" agreed on if on the shelf - especially for a PAR lamp or sealed beam lamp. Obvious arc lamps don't persay have a shelf life to worry about. Beyond that, DrewE' 's post is very important to consider also.

Me stepping away from the conversation for the rest of the week in hoping not to intimidate or overwhelm further thoughts or expansion of concept. Re-directed perhaps, is there a Covid problem with lamps installed in fixtures that is espcially the case if the dimmers were in warming current the entire year? Solution if the case presented by
gafftaper perhaps the first to notice of if this is a problem?
 

cbrandt

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Me stepping away from the conversation for the rest of the week in hoping not to intimidate or overwhelm further thoughts or expansion of concept. Re-directed perhaps, is there a Covid problem with lamps installed in fixtures that is espcially the case if the dimmers were in warming current the entire year? Solution if the case presented by
@gafftaper perhaps the first to notice of if this is a problem?
Don't talk yourself down! Your experience is key for how to handle these situations when they do occur, and what to do to make them not happen.
 

almorton

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We've got a couple of Strand Pageants in our theatre loft. We recently got one of them down to use as a prop. It still had the same lamp in it that was in when it was decommissioned well over 10 years ago. Checked the wring over, no problems, plugged it into a dimmer, brought it up, worked beautifully.
 

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