# T5 ballast help, tubes fire, then shut off?



## Jeff000 (Jun 18, 2008)

I have a 4 tube 2 ballast T5 fixture where the one ballast works great. The other ballast seems to go through the programed start and fire the tubes for a second but then the tubes shut off. I've changed the tubes with no change. 
I figure it has to be the ballast, but never had a bad ballast fire for a second and then nothing, and the fixture is brand new and I really don't want it to be a bad ballast. Any way to test? 

Thanks.


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## Bkessler (Feb 14, 2007)

Is it on a grounded circuit? electronic ballast can give you touble if their is no equipment ground.


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## Lighting Retro (Aug 1, 2009)

There's a very small chance it's a wiring issue. The way T5's are wired, both lamps on the ballast need to work correctly for both lamps to fire. If it's trying, but not lighting up completely, perhaps you have a short in the wires pushed into the T5 tombstones. If you find that isn't the case, it's probably ballast, but it's worth a check.


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## Jeff000 (Jun 18, 2008)

It is grounded, I'll rip the fixture apart to make sure the connection is good from the factory.


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## HARRY304E (Sep 15, 2010)

Jeff000 said:


> I have a 4 tube 2 ballast T5 fixture where the one ballast works great. The other ballast seems to go through the programed start and fire the tubes for a second but then the tubes shut off. I've changed the tubes with no change.
> I figure it has to be the ballast, but never had a bad ballast fire for a second and then nothing, and the fixture is brand new and I really don't want it to be a bad ballast. Any way to test?
> 
> Thanks.


That is a bad ballast they don't make them like thay used to.
I had a row of ten,thats 20 ballast and three were bad


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## CTshockhazard (Aug 28, 2009)

When I first started seeing the T5 lighting fixtures 4 or 5 years ago, they were often coming from the factory miss-wired, but has since vastly improved. The very 1st job it was 30 of the 35 fixtures that were wrong.  The miss-wired ones were doing the same thing you describe. Another one I saw that was miss-wired gave us a disco strobe effect.:thumbsup:

Field wiring can also be done wrong and cause the same issue. Check the ballast wire that is separated for individual switching of the lamps. Sometimes it's a grounded conductor, sometimes ungrounded, depending on manufacturer and system voltage.

As Lighting Retro described these ballast are designed to protect themselves from bad lamps taking them out so they will not operate if something is amiss.


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## Jeff000 (Jun 18, 2008)

So after taking apart this fixture, which happens to be one of the worst fixtures to take apart I have ever seen I found the problem, it was one of the wires to a tombstone that was pinched so bad that the insulation broke and was hitting the metal of the fixture.


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## Lighting Retro (Aug 1, 2009)

Jeff000 said:


> So after taking apart this fixture, which happens to be one of the worst fixtures to take apart I have ever seen I found the problem, it was one of the wires to a tombstone that was pinched so bad that the insulation broke and was hitting the metal of the fixture.


not shocking

some of the fixture are now made so cost effectively, they really are designed without future repair in mind. Some are SUCH a pain to take apart, and then when you do, you find they aren't quite built like you thought they would be.


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## kevmanTA (Jul 20, 2010)

Usually you can take it back to the wholesaler if you didn't already take it apart, I don't even bother finding out whats wrong anymore.


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