open metal halide fixtures

[starsandstripes]

I'm looking for opinions on dealing with open metal halide fixtures indoors. The 400 and 250 watt(especially the 250) occasionally explode at the the end of their life. Do you replace it with an enclosed fixture? Relamp with the lamp designed for an open fixture(very expensive)? Or just replace with a standard lamp and relamp when dim before the end of its life? We have hundreds of these open fixtures in our buildings. Thanks.

 

[mdshunk]

Re: open metal halide fixtures

I think that most facilities are replacing the entire fixture, or going with a group relamping schedule before the end of the lamp life.

 

[don_resqcapt19]

Re: open metal halide fixtures

The problem only occurs in lamps that are left on 24-7. If the lamps are shut down for ~15 minutes each week, they do not fail violently at the end of their life. I know of cases where time clocks were used to provide the weekly shut down.
Don

 

[hardworkingstiff]

Re: open metal halide fixtures

I thought open fixtures using these type lamps (MH, HPS, etc.) were not in compliance with U.L.

 

[starsandstripes]

Re: open metal halide fixtures

As far as UL, all these fixtures are at least 15-20 years old; None our fixtures stay on 24/7 and I have seen lamps explode twice in the last few years. Sounds like we need a group relamping program. Thanks

 

[H.L.]

Re: open metal halide fixtures

Group relamping is a good idea as it will maintain higher light levels.

H.L.

 

[tom baker]

Re: open metal halide fixtures

Because of the tendancy of MH lamps to explode at the end of life, the 2005 NEC requires a type O lamp or a enclosed luminaire.
If your luminares are as old as you say, you may benefit from the newer types of pulse start ceramic metal halide lamps.
And the trend is to install T-5 floresent, 4 lamp fixtures to replace MH lamps, they are more efficient and can be switched on and off. Your POCO may offer a energy rebate for either type.