Electronic Lighting Balasts 3

[CBravo]

Our plant is undergoing a lighting upgrade to T8 fixtures from MH fixtures. All is well in the front of the plant where the lighting uses one 480 VAC phase to neutral at 277 VAC.

The ballasts are rated to work form 120 to 300 VAC. No taps, they are intellivolt electronic ballasts.

The ballasts are failing in the installation in the addition out back where the lighing uses two hots at 208 VAC.

The electrical contractor is suggesting running a neutral conductor to all the fixtures for 120 VAC operation.

How does the intellivolt ballast know if it has a neutral connection or not? Is something fishy here?

Thanks.

 

[MacGyverS2000]

Is something floating?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[dpc]

You do need to have a grounding conductor at each fixture.

David Castor

http://www.cvoes.com

 

[CBravo]

I measure 120 volts to each phase. The supply xfrmer is a wye grounded centerap secondary and of course the fixtures have a separate ground or bonding conductor.

The only unusual thing is they have motion control switches to turn them on and off. But it's the ballasts failing, not the motion switches.

 

[davidbeach]

Are the switches switching both phases or only one?

 

[rbulsara]

Did you check with the mfr? Are these really universal ballasts? A quick look up indicates not all intelligent ballasts are universal voltage, although they do work on either 120V or 277V.

If failures are limited to just 208V application and the non -failing ballasts involve a grounded conductor, the issue may be with the application. They may have been designed to work with one supply conductor grounded, which is not the case with 208V supply you describe.

Have the ballast mfr analyze the failed ballasts and see if they can confirm the cause of the failure. Most would be happy to do it as their reputation is on line.




Rafiq Bulsara

http://www.srengineersct.com

 

[dpc]

The T8 electronic ballasts have had a fairly notorious history. We experienced mass failures on some projects, but that was many years ago.

I agree with Rafiq - best approach is to consult with the ballast manufacturer and verify these are being properly applied. 208 V lighting is actually fairly rare in the US, at least in my experience.



David Castor

http://www.cvoes.com

 

[CBravo]

The motion switches are only single pole.

Thanks for all the responses. Much appreciated. I'll have a chat with the manufacturer.

Cheers.

 

[davidbeach]

It's that single pole switching that is killing your ballasts.

 

[rbulsara]

Possibly and even if not, 208V circuit switching device need to open all ungrounded conductors. You need to use 2 pole switches/contactors.

Rafiq Bulsara

http://www.srengineersct.com