# Maybe I made a slight mistake with tombstones.



## mattsilkwood (Sep 21, 2008)

No, it sounds like the lamps had been sitting for a while or maybe just cold. They'll even out within a couple hours.


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## kaboler (Dec 1, 2010)

Dude, I hope so. I left the job feeling a bit sad, but knowing that it was 1 of 3 fixtures (2 are still T12 magnetic which should last another 20) and if it faded, they'd still have 2!

TY!


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## HARRY304E (Sep 15, 2010)

The old tomdstones have two wires....to convert just splice those together with one wire from the ballast..

Brand new lamps T 12 T 8 AND T5 Are usually dark in the middle and that will full in in about 1/2 to 1 hour...http://nemesis.lonestar.org/reference/electricity/fluorescent/trouble.html


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## wcord (Jan 23, 2011)

Yes, brand new T8 tombstones are different. They are "shunting" because there is only 1 wire going to the socket and both sides are jumper-ed together internally. As was previously posted, just join the 2 wires on the existing units and you have turned them into T8 compatible tombstones.
As an aside, if you convert a T8 fixture to a dimming fluorescent, you will have to replace the factory "shunting" tombstones with the old T12 "non shunting" style. 
When in doubt, just follow the wiring diagram on the ballast.


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## OKArchitect (Aug 6, 2013)

An detailed explanation of shunting as it applies to fluorescent fixtures is provided here:

http://www.halcolighting.com/pdf/WP/T8-IS-Retrofit.pdf

Bottom line: Instant start ballasts which are common to T8 installations require different wiring (shunting) at the tombstones in order to optimize the function of the T8 lamps - the connections to the pins at each tombstone are joined together (internally within the tombstone or externally). Without shunting, the tombstones will attempt to heat the anodes which is not necessary in the T8, and this will shorten the life of the T8.


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## theloop82 (Aug 18, 2011)

OKArchitect said:


> An detailed explanation of shunting as it applies to fluorescent fixtures is provided here:
> 
> http://www.halcolighting.com/pdf/WP/T8-IS-Retrofit.pdf
> 
> Bottom line: Instant start ballasts which are common to T8 installations require different wiring (shunting) at the tombstones in order to optimize the function of the T8 lamps - the connections to the pins at each tombstone are joined together (internally within the tombstone or externally). Without shunting, the tombstones will attempt to heat the anodes which is not necessary in the T8, and this will shorten the life of the T8.


That being said (and true) if you ever do a "Mark 10" dimming ballast retrofit on T8 fixtures make sure you get NON shunted tombstones. Don't ask me how I know that.


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## uconduit (Jun 6, 2012)

I always think of this particular tombstone when I hear "tombstone"


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## Spark Master (Jul 3, 2012)

The lamps take a while to burn in. I noticed this more on the 841's, rather than the 741's. 

The rapid start, vs. instant start. All I remember one was for a hallway, (continues lighting) and the other was for a bathroom, cycling all day by bathroom users. Not that I remember which is which anymore.

We used to do a lot or T8 retrofits. Now we install the 3 lamp T8 fixture, and trash the 4 lamp T12 fixture. Next year, I'm sure we'll be trashing the T8 fixture, and installing LED fixtures.


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