Metal halide bulb going bad?

[bmwpower]

I've got one bulb that doesn't fire up right away like the other 8 do. It keeps trying to (I can see if come on dimly, then go out, etc). It could be 1-2 hours before it finally fires up and when it does, the output is low.

(Q1) Do you think it's the bulb or the fixture that causes something like this?

Time to buy a big step ladder...no more scaffolding in the garage to change these bulbs.

(Q2) How long do you leave your lights on before you turn them off? I've heard short cycling kills the bulbs.

 

[OldCarGuy]

I would exchange the faulty bulb to a fixture that you know is working first. That way you can determine what is as fault. It’s a slim chance it’s just a loose bulb, if both the exchanged bulbs work. If the bulb doesn’t work in the known working fixture it’s the bulb. If the non-working fixture continues to be not working. It that fixture, and check out that ballast.

From my experience with metal halide bulbs it’s best to leave them running for longer periods of time with the least amount of on and offs. Never just have then on for 5 minutes or so... It will shorten their life. And the quality of light they give off will become more evident sooner.

Time to look for a taller ladder...

 

[Vicegrip]

Check the capacitor or ignitor if your fixture has one before condemning the ballast. Caps are good for 2 to 6 bulbs and when they go they can fail completely or partly and shift the bulb color. Ignitors have a service life as well.

 

[Steve in Mi]

Don't know about the MH bulbs but my outdoor MV bulbs are noticably dimmer after about two years of dusk to dawn service.

If your fixtures are the open type maybe one of the telescoping bulb removal tools could save you the trip up a ladder. I'm not fond of heigths myself so I look for a way out whenever possible.

One of these;
http://us.st11.yimg.com/us.st.yimg.com/I/organizeeverything1_1988_12240077

 

[bmwpower]

Don't know about the MH bulbs but my outdoor MV bulbs are noticably dimmer after about two years of dusk to dawn service.

If your fixtures are the open type maybe one of the telescoping bulb removal tools could save you the trip up a ladder. I'm not fond of heigths myself so I look for a way out whenever possible.

One of these;
http://us.st11.yimg.com/us.st.yimg.com/I/organizeeverything1_1988_12240077

I like. I've got a used 400W bulb I could try once I get the one in there out. 400W bulb should be ok for now, right? Fixtures are 175W. It should bump down to 175W, right?

My fixtures are closed type though.

 

[W-Cummins]

I don't think so, but I could be wrong, why don't you try it out and let me know either way...

Or of course you could do the smart thing and swap one like old car guy suggested.....

BTW why don't you have a spare bulb of the correct wattage? Did you think those things last forever? I assume that you do know that they are junk way before they fail to light. In fact they can fail rather "brightly" if you run them too long.

William....

 

[bmwpower]

I don't think so, but I could be wrong, why don't you try it out and let me know either way...

Or of course you could do the smart thing and swap one like old car guy suggested.....

BTW why don't you have a spare bulb of the correct wattage? Did you think those things last forever? I assume that you do know that they are junk way before they fail to light. In fact they can fail rather "brightly" if you run them too long.

William....

No, I didn't think it would last forever. It didn't make sense for me to have a $30 bulb sitting around waiting to possibly get damaged.

 

[OldCarGuy]

It’s always best to replace the bulb with the wattage bulb that the fixture was designed for.

One very important thing to remember is always wear clean cotton gloves when handling these type of bulbs. The oil from your hands can cause the bulbs to prematurely crack due to the heat that they produce.

 

[bmwpower]

It’s always best to replace the bulb with the wattage bulb that the fixture was designed for.

One very important thing to remember is always wear clean cotton gloves when handling these type of bulbs. The oil from your hands can cause the bulbs to prematurely crack due to the heat that they produce.

Yea, I know, I wasn't going to leave it in there perminently. I just wanted to pop it in to see if it was infact the bulb or not.

Time to buy a step ladder.

 

[bmwpower]

It’s always best to replace the bulb with the wattage bulb that the fixture was designed for.

One very important thing to remember is always wear clean cotton gloves when handling these type of bulbs. The oil from your hands can cause the bulbs to prematurely crack due to the heat that they produce.

Now I'm worried. I'm wondering if the bulb may be cracked or something.

Would a cracked bulb act the way mine is? Don't want too much UV...

 

[OldCarGuy]

Now I'm worried. I'm wondering if the bulb may be cracked or something.

Would a cracked bulb act the way mine is? Don't want too much UV...

A cracked bulb would just not light, or worst case pop (explode).

 

[bmwpower]

A cracked bulb would just not light, or worst case pop (explode).

Ok, so it' probably not cracked then. I got the impression that if the outer shell was cracked the light would still light and emit dangerous UV.

 

[Junkman]

If you install the wrong wattage bulb in the fixture, you run the risk of damaging other components. Open a known good fixture and swap the bulbs. This shouldn't be rocket science, but if it is, as a rocket scientist, I owe you a favor and will give you technical advise on how to operate the positive or negative screwdriver in the screw head to remove the cover.

 

[bmwpower]

If you install the wrong wattage bulb in the fixture, you run the risk of damaging other components. Open a known good fixture and swap the bulbs. This shouldn't be rocket science, but if it is, as a rocket scientist, I owe you a favor and will give you technical advise on how to operate the positive or negative screwdriver in the screw head to remove the cover.

I knew it was only a matter of time before Einstein showed up and saved the day! Thx!

 

[Junkman]

Einstein invented the theory of relativity......... you know, how relatives are supposed to get along. My name is Goddard...... I invented the modern rocket.

 

[Aceman]

Checking with a good bulb of the correct wattage is the easiest way. If you don't have a bulb, meter the socket, I usually get around ~230-250 volts measured from the contact tip to the screw shell. If it reads less than that, I replace the entire ballast assembly.

 

[tontruck]

Does the light change colors after being on and warming up or does it just go out completely and come back on? If it doesn't change colors or flicker then you need to check your capacitor, if it does the before mentioned it's usually the bulb.

 

[Vicegrip]

I like. I've got a used 400W bulb I could try once I get the one in there out. 400W bulb should be ok for now, right? Fixtures are 175W. It should bump down to 175W, right?

My fixtures are closed type though.

Negative. 175 watt ballast will not properly fire a 400 watt bulb. Some hid bulbs will fire without the outer envelope some have a system to detect if it is broken. If you have a glass diffuser on your inclosed fixture it will stop most UV regardless of the bulb outer envelope. Base up fixtures have a tendency to fry the socket even more so the standard HID.

Replace with same. If the fixture is hard to get to have new bulb and cap ready. A cap costs far less than a ballast or even the bulb. Install new bulb and let burn for a full day. turn off until stone cold and relight. If it does not fire or burn right from the start or on day 2 replace the capacitor or ignitor. Some smaller wattage systems use ignitor$ and they ain't cheap

 

[Jay H 237]

In the shop where I work we've noticed that when the metal halide bulbs are getting ready to go they get a pinkish hue to them a week or so before they completely fail. You can look across the shop ceiling and see the ones that are on thier way out.

 

[NAYLOR]

the sign that a metal halide bulb is about to go out is that it continually tries to restrike itself.

this is called "cycling"

 

[bmwpower]

Well, I swapped bulbs. The light is no longer cycling, but the light output is dim and also very "blue" when compared to the other lights. I'm assuming there is something wrong with the fixture. Would think point to the cap?