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haze10 (Electrical) (OP)
4 Oct 11 21:23
I am managing the relamp program for some 400 hazardous EX fixtures using 250 watt metal halide bulbs.  These are the original type, not the pulse start of the newer technology.

I've tried GE, Sylvania, Phillips, Ushio, Venture - they all dissappointed.  Bulbs are on all year, and we relamp every year.  We are seeing a lot of bulb falling within this time, about 30%.

I used to be able to get long life metal halides from a company called Wholesalelighting, but they appear to be out of business.

Who do you think is making the best MH bulb right now?
jmbelectrical (Electrical)
16 Oct 11 21:47
Given the fact that most metal halide lamps are rated between 12,000 and 20,000 hours, a 30% failure rate after one year is out of the ordinary. Have you considered the possibility of defective ballasts or a power quality issue?

To answer your question, I've always had the perception that GE, Sylvania, and Philips manufactured the best lamps. The only other manufacturer that I know of that you haven't already mentioned is EYE Lighting. I believe they offer "long life" metal halide lamps, but given your experience with other manufacturers so far, I wouldn't expect theirs to be much different.  
IRstuff (Aerospace)
16 Oct 11 22:53
Bear in mind that the rated life value is NOT when all the bulbs die; it's when 50% of the bulbs will have died.  Given that 1 yr is 8766 hrs, a 30% failure rate at 1 yr is not necessarily unexpected for a bulb rated at 10,000 hr average rated life.

If you assume a normal distribution, and assume a cumulated failure total of 30% at 1 yr, you'd get a variance of 2354 hrs, which might be plausible.

TTFN

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haze10 (Electrical) (OP)
17 Oct 11 6:31
Yes, I realize everything that is being said is true.  I know that bulbs are rated to 50% surviving at rated hours, I know these bulbs will suffer a 40% lumen depreciation at rated life.

The bulbs I have tried all met, but need not exceed, their published curves.

My question is if their are any probe start metal halide bulbs that exceed the performance of the standard curve  (10K hours for a 250MH).

There is a company on the web called bulbarama that is claiming 24K hours.  Any try these.

http://www.bulborama.com/cart.php?m=product_list&pageNumber=2&catID=&c=22&v=&r=&id=&sortBy=undefined&search=&shopByPrice=&viewAll=undefined&customListIds=&venID=

I talked with the EYE rep and they claimed a special doping solution that lasts longer and that their bulbs exceed the curve even though they are using the same 10K hour curve for their probe start.  They say they are being 'conservative'.

Has anyone tried the bulbarama or EYE bulbs to report back if they performed any better.
 
ScottyUK (Electrical)
18 Oct 11 1:23
You might want to add Osram to the list of manufacturers, at least to investigate. I've always been happy with their products in the past.
  

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If we learn from our mistakes I'm getting a great education!
 

IRstuff (Aerospace)
19 Oct 11 0:06
One thing that we've done on a totally different application is to get brighter bulbs and run them below their rated voltage.  As shown here: http://sylvaniaautomotivecatalog.wbdev.com/GenTechInfo.aspx dropping the operating voltage by 20% increases life by more than 10x.  

This is probably a more reliable way of cranking up the life, since the mechanism is not proprietary.  The only big impact is that the color temperature will be lower and redder.   

TTFN

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ScottyUK (Electrical)
19 Oct 11 1:37
Certainly an option with tungsten lamps, but maybe not as effective with a discharge lamp?
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

jmbelectrical (Electrical)
20 Oct 11 20:20
You should also consider retrofitting the existing fixtures with electronic HID ballasts. We just had a sales representative from a ballast manufacturer come to our office a few weeks ago. I was pretty impressed with what I saw. Apparently, the high operating frequency of an electronic ballast greatly reduces lumen depreciation and electrode wear. There's little, if any, audible noise, and they supposedly offer greater protection against transients.

Downsides, of course, include their cost and susceptibility to failure in a high ambient temperature environment.
haze10 (Electrical) (OP)
20 Oct 11 20:34
My problem is that these are Class I, Division 1 fixtures.  If I change to pulse metal halide I violate the UL label.   Fixtures for Div 1 have to be 'listed' for the service.  So I'd have to change some 150 fixtures at $1200 a piece.  Can't swing that cost.
jmbelectrical (Electrical)
20 Oct 11 20:50
The ballasts are backwards compatible with older probe-start type metal halide lamps, such as the ones you're using. In addition, they're available in a remote-mounted, IP-65 rated, weatherproof enclosure that can be located about 50 feet away from the fixture. I don't believe that the listing of the fixture would be affected in any way.

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