failing ballasts and lamps

[Steve]

set the scene:

new shop.

sales floor with 70-80 no. 4 x 14w T5 fittings.

warehouse with 12 no. 4 x 18w T8 fittings with prismatic diffusers.
canteen with 4 (same as warehouse) fittings
office with 2 (same as w/hse) fittings, but with reflectors.
All fittings have electronic instant start ballasts. All back area fittings controlled by PIRs.

office - tubes went black at ends quickly, both fittings flickered for a while, one after the other, then stopped working intermittently. New tubes fitted, still flickering. Ballasts on order.

canteen - one fitting after another went, this was before the office, but in the same fashion. Again, tubes badly blackened. All 4 relamped, two ballasts failed, replaced by digital ballasts. One of these is now struggling to maintain illumination.

warehouse - only one so far needed tubes, but a couple of fittings showing blackened ends.

shop floor - extensive relamping carried out, several ballasts replaced (though only half the shop floor).

What could be wrong? The only common factor is the mains supply, and the DB. I can see this carrying on indefinitely. Something is killing ballasts and tubes left right and centre. Store been open 4 months.

Sparks came yesterday to do a report, and tightened all the terminations in the DB, every single one could be tightened, they wrenched all the connections very tight. Voltages tested, ok. Internal wiring all ok.

The PIRs are the contact variety - not solid state. You can hear them click on/off, so this should have no effect on the fittings.

Anyone come across anything like this before? I know we have a few good problem solvers on here.

 

[flameport]

Most likely is bad ballasts (faulty batch if the whole building is affected)

Less likely is some issue with the supply quality - hire a logging power analyser and leave connected to the supply for a week or so.

 

[Steve]

Most likely is bad ballasts (faulty batch if the whole building is affected)

Thats the thing, a previous re-lamper fetched 2 new digital ballasts, one has failed already. The chances of that are slim to none.

 

[ricicle]

Voltage and/or supply problems.

 

[streetlighter]

Electronic ballast can be quite fussy about the variations in the supply voltage. Also when they get to warm they will start to cut out, Had nothing but problems with them in my experience.

 

[333rocky333]

Tridonic ones, and most I have seen operate between 200 volt and 260 volts.

 

[bernardgreen]

Taking a guess at this and wonder if the number of ballasts is causing some high frequency variations in the mains voltage.

Electronic ballasts are often a form of switched mode power supply taking power from the mains in a few thousand short bursts per second.

When several switched mode supplies were connected to the same supply it was found necessary to synchronise the units so they each took their burst of power from the mains supply in turn. Runing un-synchronised they could all take power at the same time and the mains voltage dipped to the point that some supplies momentarily cut out and reset.

 

[JACKC]

We have had similar at work, found all lamps were fitted with HF fittings. These were strings of 20 in a row. Changed every other to HPF type and been ok since.

 

[bernardgreen]

We have had similar at work, found all lamps were fitted with HF fittings. These were strings of 20 in a row. Changed every other to HPF type and been ok since.

Makes sense..... the power factor capacitors in the HPF acting as smoothing capacitors to reduce inter-action between the switch mode ballasts along the mains cabling.

 

[thompsk]

Hi steve, there is a damn good supplier of ballasts of all shapes n sizes at Roecliffe near Borobridge nr Harrogate, they do next day delivery and the main man would probably be able to tell you what exactly your problem is ask for geoff, if you cant find them look for G.P Electronics.