Electronic Domestic Instant Start Ballast Keeps Blowing

[RS2OOO]

Hello.

I'm no electrician (well, previously an auto-electrician but no expert on domestic electrics) and do have an electrician lined up to look into this problem next Week but would like to present the problem here for the sake of interest and for gaining some knowledge as to possible causes.

My Kitchen has 2 light fittings operating from the same supply through 2 switches.

Up until 1 year ago I had 3x 50w GU10's in each fitting.

I replaced them with a pair of (high end) fluorescent lamp fittings, 2 x PL-L 4 pin 36w tubes in each fitting.

Each fitting has an instant start electronic ballast powering the 2 tubes.

After 1 year (to the exact day!) one of the fittings flickered a few times and the 2 lamps went out and would not switch back on. Took the cover off, felt the ballast which was hot but not beyond the 70c operating temp.

The unit was exchanged under warranty.

Fitted the replacement unit and after around 30 mins of use the lamps went out (new bulbs), and would not switch back on. Replaced the bulbs (correct spec), but still would'nt work.

Now Realising the ballasts were failing I replaced the ballast and re-fitted. But again, 30 mins after use the lamps went out, this time both brand new Philips tubes were completely blackened at the ends.

So, ahead of calling in an electrician and to give him/her something to work from, I fitted new tubes and another new ballast (all correct spec etc) and put the fitting back up. Unfortunately the missus forgot and switched the light on, but this time the ballast had blown within 5 minutes and again both tubes were blackened at the ends.

The unit in question is the 2nd and final fitting in the loop, the first fitting from the same supply and using the same lamps/ballast etc works fine and continues to do so.

Polarity is correct, the ballast is earthed correctly, I have no other issues with power surges etc that I know of and all visible and accessible wiring connections are good. I've not checked actual voltage at the supply as this was something I'll let the electrician do. Haven't had any issues with blown fuses etc.

If I replace the suspect fitting with a normal 100w tungsten bulb it works and operates fine.

So my question is, what could cause an electronic ballast to blow so often and so quickly, particularly when an identical fitting just 6' away works and operates fine?

Thank you in advance for your time reading and answering this. If the problem is finally sorted I will repost to confirm what the eventual cause was.

 

[Moses]

Not sure I fully understand the wiring issue you found but I don't think reversed L/N polarity would cause premature ballast failure. That said, with electronics anything is possible.

I agree with you.

I don,t think it a mains polarity issue.

It may have been a loose/wrong connection in the wiring.

 

[RS2OOO]

Will never know with certainty if it was a wrong connection in the wiring, electrician didn't look, just ripped all the wires out and re-wired to suit the replacement ballast he had.

Anyway, appreciate the help I've had here, and really enjoy the forum in general. It's a tough job moderating forums like this (I run another forum and it's always kicking off), so kudos to the moderators as well.

Have a few photo's for the "tell us your faults" sticky thread, so I'll knock those up before I disappear.

 

[captaincaveman]

Having investigated fluorescent fittings for the last couple of hours now (as my knowledge of them was limited) i reckon your conclusion with regard to polarity is prob correct.
n.b. Wikipedia has some good info to read on fluorescents