Ceiling lighting malfunction

[Stinger]

Hello,
I am new to this forum and not an electrician. I am an Electrical Engineer though.
I have this kind of a ceiling lighting - https://www.cnmdled.com/data/watermark/20200525/5ecb8360db86c.jpg
with two fluorescent tube bulbs, two starters, one capacitor and two EM ballasts of this type -

https://www.sangchai.com/images/stories/sangchai/1-Ballast-Magnetic-T8.jpg

Both bulbs have been checked and are working. also the starters work as well.
What happens is that only one bulb is working. Everything looks connected properly.
When I cut the power to the working bulb, it shuts off but the other one comes to life, flickering all the time.
When I connect that bulb back, it returns to the previous state.
Again both bulbs are working perfectly, tested elsewhere.
Can anyone shed some light on this?

Thanks.

 

[littlespark]

You have two circuits within one fitting, consisting of starter, ballast and tube.

One circuit works perfectly.

Swap both the tubes and starters within the one fitting… If problem stays on the same side, proving both starter and tube work on the other side…. then it must be the ballast itself.

 

[Lucien Nunes]

The fact that the two halves of the fitting interact consistently, suggests that the wiring is jumbled up somehow and what should be two independent circuits of ballast, tube and starter are now interconnected. This can happen if both tube sockets at one end get detached from the body and put back the wrong way round, for example. Or, one ballast is in series with both tubes, perhaps because feed to ballast #2 is taken downstream of ballast #1 by the wire being in the wrong terminal.

I would double-check everything and reduce it to two identical circuits with every connection accounted for. The only thing not in duplicate would be the power factor correction capacitor which is normally connected across the incoming power feed and is not needed for the circuits to function correctly.

Also ensure that the voltage arriving at the fitting is correct - low voltage can cause fluorescent malfunctions and a high-resistance connection in the common feed could cause interaction, although I doubt it would behave as consistently as it seems to be doing.

 

[brianmoooore]

Same answer from me as in previous questions like this. Rip the ballasts and starters out, fit a couple of replacement LED tubes, and enjoy the savings in energy costs.

 

[Grant1987]

Same answer from me as in previous questions like this. Rip the ballasts and starters out, fit a couple of replacement LED tubes, and enjoy the savings in energy costs.

Spot on. Replace the fittings with new LED battens far better and saves the hassle of replacing starters, tubes.