# Run 14w T5 in 24w ballast/luminaire?



## nry (26 Aug 2012)

I couldn't find the answer to this on Google, so I wondered if anyone here knew if you can safely run a 14w T5 (549mm) in a luminaire designed to run 24w T5's?


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## nry (27 Aug 2012)

Has anyone got any ideas?  There's odds and sods on Google but nothing specific - it seems to be possible, but I don't want to over drive the bulbs.


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## nry (27 Aug 2012)

This suggests it may well work fine:

http://www.barrreport.com/showthread.ph ... -Fixtures!!


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## nry (27 Aug 2012)

Well, lots of credit to Arcadia!  I e-mailed them 5 minutes ago - and got a very prompt reply stating that fitting NO T5's to the OTL T5 would over drive the bulbs and burn them out.  Ah well


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## dw1305 (28 Aug 2012)

Hi all,
What ever Arcadia have told you, in the short term you definitely can. It will shorten lamp life, but you should still get several months out of the tube if not longer. 

Whether you can do it longer term depends upon the ballast. If you can open the fitting? it should have the rating on the electronic ballast. A lot of T5 ballasts will run anything from a 14W to 39W lamps. 

cheers Darrel


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## nry (28 Aug 2012)

Thanks Darrel, should be easy enough to access the ballasts, I'll have a look when they hopefully turn up on Thursday


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## hinch (28 Aug 2012)

I believe you can buy overwatt t5 tubes too which will happily run at say 25 watts when they're only 14 watt bulbs only problem is I can't remember where I saw them now


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## nry (28 Aug 2012)

I want them to run at 14w though, not 24w, that way I keep the wpg down to a sensible figure


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## dw1305 (28 Aug 2012)

Hi all,


> I want them to run at 14w though, not 24w, that way I keep the wpg down to a sensible figure


 I think that if it is a dimmable ballast they will run at normal 14W, but if they are "ordinary" electronic ballasts you may end up with a very bright 14W light. 

I first found out that the electronic ballasts had a wide rating when I wondered why 525mm 13W T5 fittings were so much dimmer than 549mm 14W ones. 

I took apart some cheap under-cabinet link lights and I found that the 13W run from the same ballast as the 4W, 6W & 8W, and the 14W ballast also ran the lamps up to 35W.

cheers Darrel


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## nry (31 Aug 2012)

It isn't a dimmable ballast, it is a Helvar EL2x24S:

https://www.bltdirect.com/product.php?pid=6012&cat=509

I've e-mailed Helvar direct, though I suspect they will say the same as Arcadia...


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## dw1305 (1 Sep 2012)

Hi all,
Looks like that is a specific 24W ballast, this means that it will "over-drive" the 14W tube which will be bright, but short lived. This is a good, very efficient ballast for a 24W lights.

The other Helvar ballast does the 14W to 35W HE T5 range. Details are here: <https://www.bltdirect.com/downloads/products/Helvar_T5_24_Watt_Twin__High_Frequency_Ballast.pdf>

cheers Darrel


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## nry (1 Sep 2012)

Cheers, someone else pointed that one out - worst case, they're around £20 and I think would be an easy replacement - for now I'm planning to blackout the white reflector plate, that should reduce things a good deal.


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