Fluorescent lights

[copey84]

Afternoon all, have had complaints about failure of fluorescent lights control gear.
Done all tests on circuits and all ok, only problem I can think of is there is a mix of magnetic and h.f ballasts on both circuits that have failing fittings. Is this a possible cause of reduced fitting life?
Both circuits are wired in twin and earth from a 3phase d/B, TT installation, only 9years old and have replaced about a dozen fittings two in particular that go more often.
Each circuit has 12 fittings that range from 2D to 5ft fluorescent, there are also emergency exit boxes that have also quit and non maintained bulkheads, one of which has failed and been replaced.
Not sure what's going on, seems to be going through to many fittings for my liking.
Appreciate any replys, thanks.

 

[Pete999]

When you say "done all the tests" what sort of tests?

 

[copey84]

Hi Pete I have done insulation resistance, r1 and r2 even done r1 and rn all ok. Checked all connections, and any failed fitting never shows any sign of damage.
Could it be h.f and magnetic ballasts on same circuit? Have replaced both types on both lighting circuits.

 

[Pete999]

Doubt very much if it is anything to do with the wiring, could be what you suggest, I'm inclined to think that it could be an age issue with voltage drop, you don't mention what size cable used so I'm guessing, clutching at straws have you checked for high resistance connections? Sorry but thats all I can think of.

 

[UKMeterman]

Hi,
Describe failing, what other loads are connected, and what is PSSC of the supply, what industry is in the building and close by?

 

[Dave OCD]

Could be an issue with the quality of the supply.

 

[copey84]

Thanks for replys, the circuits are wired in 1.5mm2 t+e, at a guess I'd say there's probably around 40 to 50m on each circuit. Have not got perspective fault currents, will measure when next on site, if needed.
The lights are wired from a 3phase sub board, there are three 3phase d/b for the installation, an 18way and two 8ways. The sub board has mainly lights and sockets, there was a lift but not in use anymore.
The loading would be typical of most spar shops with deli and petrol pumps. There is also office space and storage. It's all located in a residential area.
Do you think other loads could be having an effect. The lights on main shop floor don't give any bother and the are wired from 18way consumer along with most of the heavy 3phase loads like fridges an oven.

 

[HandySparks]

Have replaced both types on both lighting circuits.

So, regarding the switch start fluorescents; what exactly has failed? There's not much in one of these. Has the choke gone open circuit, or what?

 

[Brightspark2]

Electronic ballasts? How long are they lasting?.

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[copey84]

It must have been the ballast as lamps and starters would have been replaced. Think the latest one to fail is a magnetic type will have look later in week.
Any ideas what could cause this?

 

[Nolnoc]

As mentioned earlier a bad supply. Another I encounter is bad quality cheap ballasts (china). I've a job and every time I test the emergency lights at least 3 ballasts fail. Always in converted fittings. Nightmare to change out.

 

[copey84]

Don't think the quality of fittings are to blame, have replaced with different types over the years and still they fail prematurely. Have started to replace failed fluorescents with lamp holders until I find out whats causing this. Will check the voltage with all lights on to see if there is significant drop, doubt it will be a problem though. If anyone can think of anything else let me know, thanks.

 

[Brightspark2]

Do they have a voltage optimisation unit fitted?

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[Deleted member 72666]

Does the site have its own transformer if so check the voltages at different times of the day to include the peak demand times and the times when not much is being used.
Another thing to test for is the quality of the 3 phase supply, compare all 3 phases to each other, to neutral and to earth.

 

[copey84]

There's no voltage opt unite, the shop does have its own transformer about 30m between it and cutout.
Should have mentioned there is a factory not far from shop makes pharmaceuticals, maybe effecting supply, hard to know.
Will check voltage levels tomorrow, would have expected other equipment failure if voltage wasn't stable.
All other lights in shop that have control gear are ok.

 

[Deleted member 72666]

I would also check between neutral and earth. Btw what's the earthing arrangement?

 

[copey84]

It's a TT earthing system, tncs is available at cut out but not in use because regs for filling station doesn't allow it's use.

 

[copey84]

The failed light turned out to be a h.f fitting only in 6 months. There is a magnetic 2D fitting on same circuit only a few feet from it, so maybe it's the cause of it failing.
Measured voltage this afternoon all seems ok to me,
L1-N= 240v. L1-E=241v. L1-L2=421v
L2-N=242v. L2-E=242v. L1-L3=417v
L3-N=245v. L3-E=245v. L2-L3=420v
All other tests were ok, no voltage between earth and neutral, think it's down to ballasts.
If anyone can think of anything else let me know thanks.