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Topic Title: Fluorescent Control Gear
Topic Summary: Can I fit a bigger Choke/Ballast
Created On: 01 January 2013 11:29 AM
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 01 January 2013 11:29 AM
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74jools

Posts: 412
Joined: 02 March 2008

I guess fitting a higher wattage choke to a fluorescent batten, ie 58w in place of a 36w, won't cause any problems? I'm using the analagy of that with most things in our game, you can always oversize but not undersize!

Happy New Year to all

Julian
 01 January 2013 11:55 AM
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impvan

Posts: 826
Joined: 07 September 2005

it will cause problems, yes. Wound chokes are matched to their respective tubes. You can sometimes get wide-range chokes, but i think they're banned now due to inefficiencies.

With electronic ballasts, you can have it both ways - single wattage ones, which are cheap; and multi-wattage ones cost more.
 01 January 2013 01:20 PM
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alancapon

Posts: 5831
Joined: 27 December 2005

The idea of the ballast is that it limits the current drawn by a fluorescent tube by dropping some of the mains voltage, as well as generating the high voltage spike needed to strike it in conjunction with the starter. If you fit a ballast intended for a higher wattage tube, it is likely to pass too much current, leading to early failure of the tube (possibly explosively under some circumstances) as well as overheating of the tube and ballast.

The wattage of the tube needs to be matched to the ballast for both wound and electronic versions.

Regards,

Alan.
 01 January 2013 04:45 PM
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broadgage

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As posted above, the correct ballast should normally be used, use of a higher rated ballast will overun the lamp and lead to early failure.

In a handful of special circumstances, use of the "wrong" ballast may be justified. I have used 40 watt lamps on 80 watt ballasts in a walk in freezer very succesfully, they only lasted about 6 months of 24/7 operation but gave a much improved light.
If 40 watt lamps were used on the right ballast, then in the very cold conditions, they never properly warmed up and gave a very feeble light.

Flourescent lamps will tolerate appreciable variation in input power, but the lamp temperature is more important.
Therefore it can be worth overunning them in very cold conditions, and underunning them in very hot conditions.
In all normal circumstances though the correct ballast should be used.
 02 January 2013 01:48 PM
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AJJewsbury

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I'm using the analagy of that with most things in our game, you can always oversize but not undersize!

Try not to apply that theory when replacing fuses....
- Andy.
 02 January 2013 05:57 PM
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74jools

Posts: 412
Joined: 02 March 2008

Originally posted by: AJJewsbury

I'm using the analagy of that with most things in our game, you can always oversize but not undersize!


Try not to apply that theory when replacing fuses....

- Andy.



LOL! Thanks for that Andy, I was thinking more along the lines of Cable size and SELV Transformers etc when I used that Analagy.
 02 January 2013 10:42 PM
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Legh

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If you fit a ballast intended for a higher wattage tube, it is likely to pass too much current, leading to early failure of the tube (possibly explosively under some circumstances) as well as overheating of the tube and ballast.


I need to get my head around this one.

I exchanged an electronic ballast in a 150W HID, followed the installations instructions on box, just like a Saturday morning DIY enthusiast and it went bang.
The electronic ballast was the same wattage and fitting for the original lamp but it still went bang.
Just as well I refitted the protective glass before firing it up....

Legh

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 02 January 2013 11:20 PM
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broadgage

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What went bang ?
The lamp or the ballast ? if the ballast I would suspect defective manufacture, if the lamp went bang then it may have been life expired and perhaps had killed the previous ballast.

HID lamps contain significant internal pressure when hot and can therefore fail explosively if over run or life expired, or of defective manufacture.
If you are certain that the replacement ballast was the correct type, then that only leaves defective materials or a life expired lamp.

I dont believe that flourescent tubes can fail explosively even if abused, since they contain a near vaccuum. Gross overunning of a flourescent tube can melt a pinhole in the glass near one electrode, the ingress of air then stops any current flow.
 03 January 2013 12:18 AM
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Legh

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@Broadgage
Thanks for the info.

It was definitely the lamp, but I wasn't sure whether or not the ballast had caused it.
It didn't occur to me that a near end of lamp life may have caused the problem.
Even so, at 10 quid a 'pop', plus the cost of the ballast , the comparative cost to buy another complete fitting and limited time to replace the fitting, I wasn't prepared to experiment.

I shall have another go at it at the weekend.

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
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