I successfully bypassed a ballast to install a T8 4ft LED tube. But this time, I have a different kind of ballast (HOWARD INDUSTRIES M2/40RS-120, 60 HZ MAGNETIC BALLAST), one that can connect to 2 fixtures. Please look at the pictures: https://photos.app.goo.gl/5EnX5CT4CnNdvKsf2 On the first picture, you can see the right fixture with the ballast. The second picture shows both fixtures, right and left. On the 3rd picture, you can see well the left fixture, with no ballast. It is on the left fixture that I would like to install the led light, because it is over the stove. The 4th picture shows the left thumbstone of the right fixture. The 5th picture shows the right thumbstone of the left fixture. What wires should I cut? Where should I connect the wires?


Not a problem if 1 or 2 fixtures , there 2 kinds of ballast bypass lamps single end or double end first we need to know the type, I prefer double ended because then all existing tomb stones can be used. First if this is a double ended lamp I would tie the center. Or middle tombstones to the hot or neutral it doesn't matter then the outside one at each end to the other tombstones. If this is a single end led the tombstones can not be shunted, but if the tombstones are not shunted (the 2 contacts read open with a contunitity test) I would wire the center or middle toombstones hot on 1 side and neutral to the other of each of the center tombstones. These are the only connection options (other than if you wanted to waste wire and put them at the outside ends). Make sure to label the fixture and if single end the hot & neutral end. This will work with 1 or more lamps end to end.

  • I positively identified the fixture in my answer, if you want to tailor your advice for that. Or not, it's good general advice. – Harper - Reinstate Monica Jan 31 '18 at 18:25

Actually, it's a single fixture with two 4' bulbs... Except in this case, the tubes are end-to-end, not side by side. Electrically, it is identical to the super-common 2-lamp type, with the yellows in the middle, blue on the near end, red on the far end (instead of next to the blue). Note the red wires were extended with white (ballasts don't come with wires that long).

Also, judging by the two blue and two red wires, it looks to be a rapid-start wiring arrangement, with two wires and non-shunted lampholders/tombstones. That means you can use same-end-power LEDs just fine (though I agree with Ed Beal, I don't like them. 120V that close together? Those pins were not made for that.) Ed covers the details.

Nice lighting design, by the way. I may steal it.


Here are the pictures of my wiring: https://photos.app.goo.gl/AQjeZTGO3N7hFBUs2 . I'm sorry, I'm a beginner, do you need a picture of the lamp also? because you speak of "2 kinds of ballast bypass lamps single end or double end", so I'm not sure if the ballast or the led lamp is single or double end.

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