Flourescent Lights

[sdgfoote]

I am having problems with two flourescent light fixtures I have on a single switch. The bulbs are only lasting a short period of time <50 hours.

When new, they come on instantly but in short order they are at first slow to light, then they need to be fiddled with to light and finally they only glow slightly on the ends. The bulbs are daylight deluxe 20 watt 61cm flourescent by Phillips. They are a new low mercury type if that has any impact.

I don't know if it is the fixture, the bulb or the wiring.

The two fixtures are wired from the switch with nothing else on the circuit and conected to the ground wire.

any insight is appreciated.

[mdshunk]

I too have a lot of trouble in customer's houses with the 20 watt size low mercury lamps. They've got the mercury content so low in these lamps now that an older ballast will not always light them reliably. While Phillips is my favorite lamp brand, the shorter Alto (low mercury) lamps seems to particularly suffer. The two courses of corrective action that have worked for me are:

1) replace the lamps with standard ones (silver ends, not green ends) if they are available.

-or-

2) replace the ballast in the fixture with a modern ballast. a modern ballast will lamp the low mercury bulbs without fail. If there's nothing special about the fixtures themselves, it is sometimes cheaper to replace the whole fixture rather than just the ballast.

You can sometimes "revive" one of these low mercury lamps by taking it out of the fixture and shaking it end to end very vigorously. This stirs up the mercury and seems to make them like new for a while. I don't recommend this as corrective action. This procedure is more of a curiosity.

[sdgfoote]

These fixtures are new, purchased since this summer. Both are the same type with Pacific Ballast trigger start units.

I also tried agitating the lamp to see if it would start again, but it didn't. The fast progressive failure has me stumped. I will try changing to conventional lamps vs the low mercury.

[mdshunk]

I'm not especially excited about the Chinese ballasts. I'd put in a new US made ballast if I was servicing your unit, and would feel pretty good about the potential result. You should check the voltage to the light with a meter. Low voltages will cause this same sort of trouble. Curious... does your ballast label look like the pic below?

[Unregistered]

exactly.

Do you think this may be the root of my problem.

I can exchange the fixture at Home Depot if it will help.

[sdgfoote]

I had checked the voltage at both fixtures and it is correct and the same at both.

[Wgoodrich]

Two things that come to mind that may be in the picture on this one not yet mentioned is one if garage unheated a rapid start fixture will not work very good below 55 degrees. Also check to make sure the ballast is connected to the equipment grounding conductor of that circuit. Don't just check to see if the grounding wire is connected in the fixture. Take that wire loose hanging in air and test with voltage tester between the hot wire and that bare or green wire connected to the metal frame or ballast required to connect equipment grounding to that light. These tubes rely on that equipment grounding to ignite the gases.

Just added thought

Wg

[sdgfoote]

The lights are indoors at room temperature.

I just confirmed there is continuity between the white wire and ground when the power is removed from the fixture and there is ground with the ballast and the ground wire coming in.

[Wgoodrich]

If these ballasts are older and your voltage is in range then sounds like replacing the ballast or entire fixture which ever is less expensive and pleasing to you. Suspect the ballasts are getting weak causing hardship while igniting the gases of not compatible with the tubes being used as mentioned earlier.

Hope this helps

Wg