I have a Keystone KTEB-240-1-TP ballast I want to bypass. But it’s wiring is different than diagrams I find. This ballast just has red and blue wires that go to the lamps. All the reds go to the 2 ends of 1 lamp and all the blues go to 2 ends of the other lamp. No yellows or pigtails that connect the 2 lamp ends or anything. Do I just put the black with all the reds and the neutral with all the blues? Do I skip wiring one end? Help!

  • Why do you want to bypass the ballast? How about some pictures of the diagrams you're looking at.
    – JACK
    Commented Sep 18, 2022 at 18:43
  • @JACK gets it right (once again!), why? Is this an XY problem? If the existing ballast had failed and you can find 120volt bulbs for a direct replacement of the size of your existing bulbs, you can completely eliminate the ballast altogether ("you can completely eliminate the ballast", SORRY, had to do it, from a clip in the movie Airplane. Snip me if needed. Anyway, wiring instructions should be included with the 120v bulbs (tubes) and they are super simple. No ballasts, no starters. The fixture needs to be labeled as having been converted, but that's just a sticker normally included. Commented Sep 18, 2022 at 20:00
  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Commented Sep 18, 2022 at 20:50

1 Answer 1


Generally, you ignore the ballast and look at the wiring to the "tombstone" lamp-holders.

You are correct - All the wires to the lamp-holders at one end of the fixture, go to hot. All the wires to the lamp-holders at the other end of the fixture go to neutral. It doesn't matter which end, just that they're all the same and no wires run from one end to the other (because that would make a short).

Here's the wrinkle, though.

LED conversions haven't been very well thought-out. Those little pins at the end can have 120V across them under ideal conditions, but I would not trust them with 120V under less-than-ideal conditions such as condensing humidity, a grimy shop with metal dust, or anything like that. It really is better to put all hots at 1 end of the fixture and all neutrals at the other end.

But businesswise, LED "tubes" have been a "gold rush". Lots of cheap unsafe garbage out there from you-know-where. The favorite trick of the cheapsters is to wire the LED "tube" so that hot and neutral are both on the same end of the "tube". That saves them 0.3 cents per "tube" since they don't need to run a wire to the far end.

But if they did that, this creates a real problem for you. Now you are going to have to totally re-wire this fixture. Those "tombstones" (lampholders) in your lamp don't actually have 2 pins. They are "shunted" meaning their 2 pins are internally connected to each other. You'll need to pull out the tombstones, identify their shape, find a compatible tombstone (they're not all compatible, trust me!), mail-order that, could be $5-10 a tube by the time it's all said and done... and then entirely rewire the fixture.

Nuts to that! If you got "single-ended" LEDs, send them back. Get double-ended LEDs, which tend to be from more reputable makers anyway. Because that's a sure thing. Taking apart fluorescent fixtures is always a dodgy affair. Some of them won't go back together!

I convert hundreds of fluorescents, and that's my experience.

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