Dim 277V Metal Halides

[jclint07]

Hope all are taking care of their employees in this heat! It's terrible in Missouri this week! Alright, had service call to a 5 year old big-box store this morning, for dim lights. There are 330- 350W Metal Halide Hi-Bay lights. Back in Dec. 09, Store Manager complained to corporate of all 330 lamps becoming dim, not as bright as when they were new(5 years ago.) So all 330 fixtures were relamped, in January of this year. Store Manager says lights were back to full brightness for around a month, then gradually they all have become dim again. Some are even a "greenish"color. Their Maintenance Employee recently changed 4 ballast/capacitors/lamps in 4 fixtures, and those 4 are back to full brightness. Noticably brighter compared to the other 326 fixtures. I believe he installed those 4 around 4 weeks ago. Utility Secondary coming in is 480/277V. Had them verify voltages this morning. 471V, 471V, 480V is what lineman told me. "Low but within their parameter", were his words. There are 2-208V/120V XFR's in use for this building, to serve receptacle loads. Voltage at both Lighting Panelboard was A-271V, B-276V, C-276V. But dim lights are not contained to a certain phase, they are through out building. Just for grins, I swapped a bulb from one fixture maintenance just replaced ballast in, with bulb from fixture producing "greenish" light. Greenish color bulb turned white in fixture with new ballast, but was dim like rest of store fixtures. Put bulb back in that fixture, with new ballast, that maintenance had put in there, goes back to full brightness. All Bulbs are labeled exactly the same. Label on Fixtures say "Pulse-Start Lamps/350W ONLY. 277V/208." Lamps are GE CMH 350W. I told Store Manager I would come back, after I spoke with their Maintenance Guy about what exactly he did. He may know more than what they think he knows. Any ideas??

 

[The Lightman]

Approximately six years ago, ballast manufacturers switched from standard oil filled metal capacitors to dry, plastic caps. Every day I replace melted or blown out plastic caps with metal. Replace the caps on the green or dim fixtures and they will be fully lit.

 

[jclint07]

Thanks Lightman! I was not aware of manufacturers changing to dry capacitors 6 years ago. These HID fixtures were installed 5 years ago, so that makes a little better sense. I am in process of tracking down vendor these fixtures were purchased from, to possibly find out if others have had same problem (greenish light, dimness) as this store. In your experience with HID ballast & capacitors, do you think Phase A having a voltage of only 271V instead of full 277V plays any kind of part in ballast performance/life expectancy? The ballast job is to "transform" the input voltage anyway, correct? Corporate may be better off updating all 330 fixtures to High-bay T8 Fluorescents, saving energy, instead of paying to replace all the caps. Not quite sure of the life expectancy of the original ballast, as well. 5000 hours/yr is what we are basing their usage off of.

 

[mcclary's electrical]

10% light loss is normal within a year. I would be weary of replamping things just because someone says they are "dim". I'm sure they did lose some light output in the first month. Use your light meter to record variations from new to old. Change a few and monitor WITH YOUR METER, don't go by"they look kinda dim",,,,keeep in mind this could be a manager that is impossible to make happy. If you made NO PROMISES of brighter light, then you did your job. YOu changed bulbs, the buck stops there. However, if you promised them 10% more light or something like that, you've got some monitoring to do.

 

[jclint07]

No, my company is not the one who relamped fixtures four months ago. That out-of-state company was hired by corporate, and I'm sure they are long gone by now. I was brought into the equation because my company is getting into business of upgrading older,commercial buildings with newer, efficient lighting. Store manager, employees & customers are the ones complaining about dim lights. It is VERY noticable. My educated guess is that 326 fixtures are around 25% dimmer than the 4 that have brand new ballast installed one month ago. The fixtures that are burning great, which is only 4, are so bright, you can not even look at directly, as one would expect with 350W metal halide. The dim ones you can actually get next too and read the wattage of the bulb printed on the glass, while they are burning, which I realize is NOT recommended at all. My supply house is working with me on putting together quote for just replacing all 330 fixtures, with High-Bay 6 Lamp, T8 Fluor. Fixtures. Either way, it is going to be a costly fix. Thanks again All!!

 

[480sparky]

Try these:

 

[hurk27]

Arch lamps as well as fluorescents do not change in brightness as much as incandescents do, and it takes quite a drop in voltage before is is even noticeable, I agree with the cap problem as these are in series with the lamp, and can limit the current to a lamp which will cause it to dim, burn green, Etc...

I'm surprise you like the T-8 high bays, I used the T-5 54 watt 6 or 8 lamp reflector high bay, I get them from RUDD prelamped and corded with a twist lock, and fast swap them out with verity of high bays, these fixtures are so bright you can't even look at them but a 6-bulb will give you about 26k lumen's and a 8-bulb will be about 30k which is much brighter then a 400 watt MH. I have done many warehouses and stores, shoppes and even a few truck garages where the only problem I had is the diesel smoke just blackened the reflectors and lamps, but after installing clear lexan covers that they can clean, never had the problem again.
The nice thing when replacing a MH with a fluorescent high bay is the fact it is instance on when power goes out and comes back on.

 

[jmellc]

Did you check voltage at any of the lights themselves? I had some 277 MH ckts where I had 277 at the panel but 250 to 255 at the lights. I repulled the home runs in #10 and got voltage up to 272 or so. Helped a lot.