Lamp life - Contractor Talk - Professional Construction and Remodeling Forum

illuminata · 02-29-2008, 09:56 AM

I think I am suffering reduced lamp life in some fixtures on a large property we service but before delving in to the system or marking lamp change dates on them I thought I would tap into this forum to compile a list of what factors effect lamp life.

So far I have:

voltage, under or over
crappy lamps
crappy fixtures
mechanical abuse in transit
"bad batch"
touching of halogen's envelope

Anything else?

MALCO.New.York · 02-29-2008, 10:15 AM

Voltage is the greatest offender in this scenario.

NightScenes · 02-29-2008, 05:54 PM

I would say that the list you have pretty much covers it. I would say that shipping can be an issue for lamps as well. I have also found that so-called extended life or "ultra" lamps do not live up to their claims.

illuminata · 02-29-2008, 07:11 PM

I thought this was about it.

The system I am concerned about is a hybrid 50/50 our installation/previous installation. I suspect it is my stuff that seems to be failing early though I only have anicdotal eveidence. However, there are over 200 fixtures on this property and we go back about once every 4-6 weeks so I might just be imagining things. Though I changed rather a lot of lamps yesterday. Of course we are in the darkest part of the year and they are running dusk-dawn. They are also mostly running at 10-11 volts.

I think I am going to start marking a date on the fixtures in some way or leave a date tag inside. Any good suggestions for how to do this?

NightScenes · 02-29-2008, 08:24 PM

Mark the back of the lamp with a sharpie.

TDLMN · 03-07-2008, 04:41 PM

Another possible cause of lamp failure is ambient temperature...I have been working on understanding the effects of temperature on cable resistance. From what I have found cable becomes more efficient as the temp. drops. That means that as it gets colder resistance is less thereby increasing voltage to the lamps. Because you are in MI most systems are installed in the summer when temps are warm and resistance in cable is high...just remember the voltages we set during the summer will increase during the winter. The cable constants that we use in the voltage drop calculations were determined at 72degrees F in a lab. I am finding that there is about a 2% change in the cable constant for every 9 degree change in temp from 72degrees F. This same effect occurs in the Transformer as well...because of the copper windings. I started looking into this because I live in MN and @ -30 we loose a lot of lamps. I am now recommending that those of us who live in these extreme cold temps begin to lower our voltage settings in the summer to compensate for the increase in voltage that we will experience in the winter. All of the other potential causes you mentioned are also possible but I bring this to your attention as just one more thing to consider.

Best,
Gerry De La Vega
President
TerraDek Lighting Inc.
1-800-609-1130
terradek.com

illuminata · 03-07-2008, 05:11 PM

That's very interesting. Combined with the extended running time in the darker, northern months the lamps don't stand a chance.

Let's see 72F to 15F is about 12% change in resistance? So 11.5v could now be 12.9v? That would do it.

Maybe we should only install in winter or bury cables below the frost line.

NightLightingFX · 03-16-2008, 12:46 PM

Illuminata,
The point that Jerry made is very true. I installed a system almost two years ago in the hottest time of the year. Without even thinking about it I did my voltage testing at the hottest time of the day. I have had nothing but problems with this system. Upon going back and checking voltage etc. in the winter I had lamps that were getting 12.5+ volts. Another thing is just because a brand claims 10,000 hours that doesn't mean squat. I am spending the extra dollar and using the highest quality lamps. I will NEVER EVER use a Prism lamp for as long as I live.
~Ned

illuminata · 03-16-2008, 01:57 PM

Quote:

Originally Posted by NightLightingFX

Illuminata,
The point that Jerry made is very true. I installed a system almost two years ago in the hottest time of the year. Without even thinking about it I did my voltage testing at the hottest time of the day. I have had nothing but problems with this system. Upon going back and checking voltage etc. in the winter I had lamps that were getting 12.5+ volts. Another thing is just because a brand claims 10,000 hours that doesn't mean squat. I am spending the extra dollar and using the highest quality lamps. I will NEVER EVER use a Prism lamp for as long as I live.
~Ned

I am using Prism lamps at the recomendation of my distributor. Do you think they are of poor quality then? I haven't really noticed a problem and most of the ones on my own system have lasted over three years. But if there is something more reliable out there I should use it. What does everyone recomend?

NightScenes · 03-17-2008, 06:45 AM

I would stay away from Prizm or any of those other cut rate lamps. I recommend either Ushio or GE Constant Color lamps.

James Solecki · 03-17-2008, 11:09 AM

Quote:

Originally Posted by TDLMN

Another possible cause of lamp failure is ambient temperature...I have been working on understanding the effects of temperature on cable resistance. From what I have found cable becomes more efficient as the temp. drops. That means that as it gets colder resistance is less thereby increasing voltage to the lamps. Because you are in MI most systems are installed in the summer when temps are warm and resistance in cable is high...just remember the voltages we set during the summer will increase during the winter. The cable constants that we use in the voltage drop calculations were determined at 72degrees F in a lab. I am finding that there is about a 2% change in the cable constant for every 9 degree change in temp from 72degrees F. This same effect occurs in the Transformer as well...because of the copper windings. I started looking into this because I live in MN and @ -30 we loose a lot of lamps. I am now recommending that those of us who live in these extreme cold temps begin to lower our voltage settings in the summer to compensate for the increase in voltage that we will experience in the winter. All of the other potential causes you mentioned are also possible but I bring this to your attention as just one more thing to consider.

Best,
Gerry De La Vega
President
TerraDek Lighting Inc.
1-800-609-1130
terradek.com

Gerry.. this is VERY interesting information! Especially to one who lives and works in this frozen wasteland! (Is it every going to melt and go away?)

From what you suggest, I should be setting my lamp voltages at just near the lower limit (say 10.9-11.0V) during the heat of the summer to accomodate for the reduced voltage drop that the system will experience in the winter?

We have another nasty situation to deal with as of late. Ontario Hydro is regularly reducing the voltage on the grid on the hottest days of the year to reduce overall megawatt consumption in the summer. Normally we get 120 to 122 volts year round, except during heat waves in June, July and August. On these days the grid will be lowered to 115 volts. This really plays havoc with setting up LV outdoor lighting systems! It is to the point that we have to constantly monitor primary side voltages during the summer and try to compensate for that at the time of installation, or return later to balance the system under 'normal' conditions.

Thanks for the information Gerry... keep it coming!

NightLightingFX · 03-17-2008, 06:10 PM

Illuminata,
BINGO! If you are using Prism. I bet your problem is due to the poor quality of lamps. I have had nothing but problems with that brand.
~Ned

illuminata · 03-19-2008, 09:14 AM

Quote:

Originally Posted by NightLightingFX

Illuminata,
BINGO! If you are using Prism. I bet your problem is due to the poor quality of lamps. I have had nothing but problems with that brand.
~Ned

Like I said earlier, I haven't thought that the Prizm were performing poorly but perhaps I have suspected it. Once I get through my current stock I will switch to either Ushio or GE. What should I expect to pay for these brands in a BAB say? I currently pay $4 each for the Prizms.

NightScenes · 03-19-2008, 04:06 PM

You're getting ripped off if you're paying $4 for a prism lamp!! Why wait to change the brand. The more prism lamps that you install, the more call backs you're going to get and it will cost you a lot more than those Prisms did. Use those lamps in your demo fixtures and get switched over to a good lamp ASAP. I can't tell you what I pay for lamps because I buy them in very large quantities but I will say that you are getting the shaft at that price.