I hope someone can advise me. I'm trying to insert an F40 bulb (1.5" diameter, 4' long) into the socket shown below. With every other fluorescent socket in my home, I simply orient the two bulb pins vertically, push the bulb up into the socket, and then rotate the bulb 90 degrees. But as the photo shows, I can't insert the bulb vertically, because that path is blocked. I must be missing something obvious... can anyone help me? Thank you!


socket photo

2 Answers 2


Yeah, that's just a wacky "feature" of this particular type of tombstone.

Yes, that little black sleeve rotates independently from the white tombstone. In theory, it's supposed to be impossible for it to be in that position - since you would have had to turn it 90 degrees to remove the tube. However, if the tube broke or was cleverly removed in some other way, it could wind up like that.

So, you need a "key" to turn it 90 degrees. Look close at the end of a fluorescent tube, see the 2 pins? Why, that's the key right there! :) You just stick one end of the tube into the socket with the pins horizontal, and engage those holes... then turn it 90 degrees (should be a small detent) and you're all set.


You insert the tube into the socket (the black ring in your picture) on both ends of the fixture such that the prongs are in the 12 and 6 o'clock positions. Then you gently rotate the tube 90 deg so that the prongs are in the 3 and 9 o'clock positions. In this position the prongs then make contact with the brass colored fingers in the socket.

  • The black ring needs to be positioned so that the pins can be inserted and slid up in the 12 and 6 o'clock positions.
    – Alaska Man
    Apr 19, 2020 at 18:09
  • So IIUC, I can't just insert the bulb, right? My problem appears to be identical to this: diy.stackexchange.com/questions/85291 . First I have to somehow rotate the black ring 90 degrees, and then I can insert the bulb by sliding it in vertically in the usual way. Is that correct?
    – David E
    Apr 19, 2020 at 18:22
  • Out of curiosity, how was the precious bulb removed?
    – DJohnM
    Apr 19, 2020 at 19:52
  • @DJohnM , I confess that I have no idea how I managed to remove the bulb and leave the tombstone in that state. However, I'm not the one who put the original bulb in; it might have been installed incorrectly from the start. I admit that's unlikely... but I'm resigned to the fact that I'll never know what really happened. If I can just get a new bulb in now, I'll be happy!
    – David E
    Apr 20, 2020 at 3:10
  • This is how a pro would do it using the pins of a tube +
    – Ed Beal
    Jul 7, 2022 at 13:13

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