I am installing a New T8 Single tube ballast to replace an older ballast. The new ballast has one black wire, one white wire, two blue and one red. The old ballast has two wires coming and going from bulb mounts. How should I wire the new ballast?

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    Are you sure you don't have a 2-lamp ballast? Generally speaking you will have 2 blue wires and one red for a 2-lamp-er. – ChiefTwoPencils Nov 10 '15 at 8:03
  • Chief, you're thinking of instant start ballasts. They have 1 wire to each bulb end. His old ballast was a rapid or programmed start ballast which have 2 wires to bulb ends, since they preheat the bulb filaments in each end. I gather he is switching to an instant start ballast intended for 2 bulbs but rated for 1 bulb also, which the electronic ballasts can do. – Harper - Reinstate Monica Feb 2 '16 at 18:41

The new ballast should've come with a wiring diagram. It might even be printed on the ballast itself.

In general I think most (all?) T8 ballasts have blue wires going to one end and red wires going to the other. Are you replacing a T8 ballast or something else? T12s are wired differently so make sure to follow the new ballast's wiring if you are replacing an older one.

  • His original was possibly a magnetic single lamp ballast. The replacement he's describing is a two lamp ballast instant start. For single lamp use as follows, Black = incoming line hot, White = incoming line neutral, Red = common shared by both lamps, for single lamp one end of tube, 2 Blue = Cap one, the other goes to the other end of the single tube. Electronic ballast wiring diagrams are a dime a dozen on Google image search. And printed on all the replacement ballasts I've ever bought. And if it has a starter, that no longer is used in the newer ballast circuitry. – Fiasco Labs Jul 24 '16 at 15:53

I found this video that might help you out: https://www.youtube.com/watch?v=zLvawsR5xyE

And if you prefer PDF documents on the subject, this one from GE is pretty good: http://www.gelighting.com/LightingWeb/na/smartcatalogs/Lighting_and_Ballasts_Section_10_Ballasts_T8_Instant_Start.pdf Much more than you want, I bet, but look on page 10-61 and there are wiring diagrams for various ballasts.

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