277 volt dimming ballast - yuck!!

[sundowner]

So I'm trying to replace an existing 277 volt 678-A-TC - ( 2 T12 40 watt tubes, with 277 volt dimming ) in a troffer in one of my office complexes. Old ballast shot, replaced because building guy "tried" to fix the original one. No dice - I finally found one - 3 weeks out, wire it in - tubes just kind of "flutter" at about 25%. The entire room - all 18 fixtures - are all the same, all working nice. Other fixtures are over the top of occupied desks so I'm reluctant to open these up and see the wiring.

My question is - what the heck am I doing wrong, what is the deal with disconnect style tombstones and can I omit them and just use non-disco tombstones - if so what do I do with the other leads from the ballast. Is my wiring screwed up - it must be - - anyone have a diagram of disco type tombstones I could see??

Any help would be really nice - already got a couple hours in on this and not any progress.

Thanks guys!!

 

[ActionDave]

I don't know what you mean by "disconnect style tombstones". Dimming ballasts do require different wiring than standard ballasts. Did the hanyman scramble up the wiring inside the fixture?

 

[iwire]

I don't know what you mean by "disconnect style tombstones".

The sockets that take the single pin tubes are often wired in a way that kills the feed to the ballast as soon as you remove a light.

sundowner, it used to work with those sockets why would you think they need to be changed?

If it was me I would get over a desk and check out an old one to look at.

 

[iwire]

Dave, see how they run the line through the socket?

When you pull the lamp out it kills the ballast.

 

[ActionDave]

Dave, see how they run the line through the socket?

When you pull the lamp out it kills the ballast.

That looks like a non electronic, eight foot T-12.

 

[iwire]

That looks like a non electronic, eight foot T-12.

The OP is dealing with 4' T12s, I bet they were not electronic.

 

[ActionDave]

The OP is dealing with 4' T12s, I bet they were not electronic.

Ohhh. I didn't read close enough. I saw the word troffer and my brain filled in the rest.

 

[Chamuit]

Could a wire have pulled out of one of the tombstones?

 

[sundowner]

No wire pulled out - checked - - so I called MagnaTech - the ballast manufacturer - tech support guy says these are so old they are completely obsolete!! Great!! My purchaser is having a hell of a time finding one also- maybe a rebuilt one for 280- plus freight - YEESH - I can throw a set of LED retro tubes in there for 40 bucks!!

So if I look at the schematic on the ballast it doesn't show exactly the connections - but are you guys saying the 277 volt line does in fact go to the tombstone - then to the ballast, cuz that aint how I got it wired - maybe thats why they just kind of sputter??

I would think if I'm pounding secondary Voltage on the tubes they would light up ??

 

[JFletcher]

Would something like this work? If the existing ballasts are obsolete and near $300 ea, maybe it's time to change 'em all out to LED and be done with it.

I agree with iwire re: looking at another fixture to see how it's all wired. I know it's a pain with the desks and all, but they've a much better chance of being wired correctly if the maint. guy hasnt touched them.

 

[sundowner]

Thanks guys...I'll sweet talk one of the "hoity toity" gals into letting me set up a ladder above her area and see what the heck is going on on Monday. I'll check out another ballast and see what I'm missing. Everything else in the room is OK.

P.S. The "maintenance" guy and I have a new "understanding".