fluorescent light problem

I can't answer all your questions but can suggest that corrosion of the contacts is a possibility. Also, I have found that the contacts lose their tension. Touching the cabinet? That's strange ... I'll be curious to see if you get any replies about that!

Hi Michael, Since its the bathroom I would bet on the corroded contacts. Sometimes even the slightest coupling to ground or AC Hum will cause a borderline lite to come on. Next time you see one flickering run your finger up and down the tube and see what happens. regards, Tom

It is possible you have a poor ground or neutral connection.

Cheers!

Chip Shults My robotics, space and CGI web page -

Michael, the symptoms that you describe are characteristic of a fluorescent light housing that is not properly grounded. You may want to check the grounding on these fixtures.

Harry C.

By coincedence, the new ballast transformers were defective, or there was some type of electrical problem. A knowledgable electrician should have been able to work this out for you.

Jerry Greenberg

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Yup ... I forgot to add that touching the glass tube also causes the tube to come on fully.

I used to have old circular fluorescent on the ceiling in my own kitchen and in cold weather it would do the come-on-dim thing. Reaching up with a metal broom handle and touching the glass tube made it fire. I finally ripped the thing out.

Possible, I guess, but I did try to make good connections by continuously rotating the tube for about half a minute. Did that just to make sure ..... in desperation, because I never did like or trust the contacts in fluorescent tube sockets.

I'll definitely check ground connections next time I visit home. Since touching the metal cabinet around the light has an effect, it seems likely that the cabinet does *not* have a solid ground. I don't understand though why two lights - one upstairs and one downstairs - worked fine for about 10 years.

1. Are the ballasts 2-bulb ballasts? Especially "trigger start" ones?

If one bulb glows dimly and the other one does not glow at all and you tried new bulbs:

a) The fixture needs to be grounded. Failure to start due to lack of grounding is often inconsistent and may vary seasonally. If touching a bulb or the fixture helps, then chances are the problem is lack of proper grounding.

b) A hot-neutral reverse may cause this.

c) Check the voltage across the two contacts in each socket - it should be around 9 volts.

d) Try twisting the bulbs around for better contact. If this fixes it, then you will have to clean the contacts in the sckets with fine sandpaper or get new sockets (lampholders). It may be easier to cut new lampholders from a ballast that has them or from the cheapest new fixture you can find than to find a supplier that sells just a few of them.

e) Make sure you have the proper wattage bulb for the ballast. Nowadays

2-foot (and worse still 4-foot) fluorescent bulbs come in different wattages.

Same story if both bulbs are out.

If all bulbs glow dimly then the problem is almost certainly not improper grounding or hot-neutral reverse.

1. Bulb glows dimly with a single bulb trigger start ballast: By far the most likely explanation is poor contact with one pin, or maybe with one pin on each end of the bulb, or broken connection that results in lack of that roughly 9 volts across the pins on each end.

1. Both bulbs glow a little dim but not very dim, and/or flicker rapidly in unison, or alternate between normal brightness and dim or dim/flickery in unison, and the bulbs are known good: Some 2-bulb trigger start ballasts, especially for 20 watt bulbs, are marginal in design. Try a different brand of bulb. Be sure you have the proper wattage bulb.

2. If the fixture has starters:

Voltage measurements across the two contacts of each socket will be meaningless and ideally read zero but could be anything depending on the impedance of your voltmeter.

Try replacing the starters, although bad starters usually cause symptoms other than the ones you described. Bad starters can cause rapid degradation of good bulbs and bad bulbs can cause bad extra wear on good starters.

1. Try reading:

(Sam Goldwasser's F-lamp FAQ) (my troubleshooting guide)

- Don Klipstein ( snipped-for-privacy@misty.com)

In strange static-assisted cases, try cleaning the bulbs. In a few areas especialy coastal areas, a very fine salty film on the bulbs may, at times of higher humidity, mess up the electric field distribution within a bulb that is trying to start. This is almost certainly not the explanation if all bulbs are glowing dimly rather than any bulbs not glowing at all.

- Don Klipstein ( snipped-for-privacy@misty.com)

So much good stuff. Enough to keep me reading for quite a while. I have a good feeling that what I need to know is in there somewhere. Many thanks, Don.

Many florescent fixtures need to be grounded to fire properly. Two wire fixtures need the correct wire connected to the neutral and hot. If they are reversed, they will be hard to start. That you can touch yours and have them start indicates you may indeed have a reversed hot and neutral.

-- Dan Fraser

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