Hello and happy holidays to all. I have not really done anything related to lighting service but I have a friend who asked me to look at a metal halide light that keeps going on and off. It comes on and stays on for about a minute, then goes out for a few, comes on for another minute, and so on. Any suggestions on what to look at? I will take a look in the technical reference to see how these things are supposed to work. Thanks

Jim

Try a new lamp if it still does the same thing buy a ballast kit.

Do not leave a new lamp in place if it does not stay lit, you will just kill the new lamp.

You may also want to test the photocell on the fixture, if there is one....

Although it's not as common for MH lamps to do this as a High Pressure Sodium, it still happens.
Just replace the lamp...S

[This message has been edited by electure (edited 12-19-2003).]

Sounds like an end of lamp life scenario.
Arc tube would be noticably darkened, or sometimes a bit warped.

Also may be an indication of:
<OL TYPE=A>

[*]Input AC Voltage Is Too Low,

[*]Incorrect Lamp / Ballast Matchup,
or,

[*]Excessive Heat Trapped Within Luminaire.
</OL>

Don't exclude a "Logical Paradox" setup between the fixture and a Photocell which controlls it!
(Light from fixture shines on Photocell, Photocell turns off Lamp; No light on Photocell, so it turns on Lamp; Lamp produces light output which is detected by Photocell - Photocell turns off Lamp; No light on Photocell, so it turns on Lamp: Light detected by Photocell..... yadda yadda yadda!!!)
In BASIC, this would look like:

10: P AT 100: "Light On/Light Off"
20: GOTO 10
run


Scott35

Change the bulb, see this all the time.

also if this metal halide lumaire do have thermal protcter in the ballast housing ..

some "f" metal halide ballast do look like fluroscent ballast if so it will useally come with overheat protiectin in there.

i did see it happend when the insluation got too close to the ballast housing and do weird way .

merci, marc

I will look into replacing the lamp, it was in use for about a year, what is the average lifespan of the bulbs? If I remember correctly this unit is on 110, there is no photocell because this is an indoor installation. It is mounted right behind another much larger, I think about 250 watt this is a 90 watt, light, could heat be an issue? They are wall mounted in a rather large old warehouse, now an indoor rock climbing gym so there is also a lot of dust. I appreciate all your quick responses.

Jim

I use to go to a supply house, they had their own lamp tester. I don't think too many supply houses would bother investing in one these days because metal halide and hps bulb prices are so cheap now.