Fluorescent light troubleshooting

Hello,

There is a fluorescent light in the kitchen that has not been working properly for a while. If you turn the switch on, the light will light dimly, or not at all. After a while (or tapping the side of the fixture repeatedly) it will come on to full brightness. What would cause this kind of behavior? Would it be costly to repair?

Thanks!

 

Start with brand new bulbs and see what happens.

 

First thing is try the new bulbs if that work if not then you will have to check the tombstone sockets to make sure they are clean as well that two most common non ballast related issue with flourscent luminaires.

Merci.
Marc

 

The lamp is 25-30 years old, if that helps. It's been exhibiting this behavior for about 5-8 years now. Haven't tried new bulbs yet. I have to get the specs.

 

While fluorescent lights will give off light for many years they get dimmer with age so even if they still work they need to be replaced if they are more then 3 or 4 years old.

 

I took the translucent cover off of the light and it seems to work fine now. Not sure why that would have any affect on it. The fixture has 2 U-shaped fluorescent tubes which read: "PHILLIPS ECON-O-WATT FB40CW/6/EW".

ray2047, I did not see anything like the picture you posted.

 

As suggested check the sockets for corrosion then replace the bulbs.

While not likely if the covers are really tight you might have had higher humidity inside. Fluorescents don't work as well in high humidity.

 

It just sounds like bad bulbs to me. It would be rare for a bad magnetic ballast to ever bring the bulbs to full brightness. By the way, bulbs are normally referred to as lamps.

 

Here's another one (sorry for all the questions):

There is a T12 fixture in the garage that has had burned out bulbs for a while. I took the specs from the existing bulbs and bought new ones today. I replaced all 4 bulbs in the fixture. However, only the inner 2 bulbs are lighting. The outer set is not. What would cause this?

 

A four tube fixture often has two ballasts. If the lights working are on the same ballast I would suspect the other ballast if the connections looked good and no corrosion on the tombstones.

A bad ballast may be cold to the touch or much hotter then a good ballast. It may have what looks like tar running out.

 

Ray got on the spot and majorty of the rapid start ballast are useally designed for two lamps only very rare to see they work more than two lamps due the design of the circuits { sign ballast is diffrent beast so we will leave this out for time being }

So with bad ballast you will either feel cold or very hot one of the two.

But check the connections as well if they were good and tight then ballast is history so you have couple choice is replace with other rapid start ballast or replace with electronic instat start ballast so a single ballast will deal all 4 lamps and you will have to switch over to t-8 lamps anyway.
Or get new flourscent luminaire the cost of ballast is pretty low unless you have one off luminaire then you can replace the ballast.

Typically two lamp rapid start ballast useally run about 15 to 25 Euros depending on where you get it from but electronic verison will cost more but it super quiet they will run anywhere from 20 to 50 Euros again it depending on where you get it.

Merci.
Marc

 

I removed the access cover which exposed 2 ballasts (and lots of messy wiring). However, when powered on, neither ballast seemed noticeably hot or cold. Also, the two bulbs that are working have this kind of swirling effect when first turned on - is this normal?

 

The swirling is normal for new lamps.

 

Sometimes you just have to bite the bullet and try a new ballast (with fingers crossed) or buy a new fixture.