An electrician I recently got a bid from made a number of recommendations involving installing what he called "Four-Oh" lights. I wasn't sure I was hearing him right, so had him spell it out. He told me there are great fixtures which are labelled "4/0" and that, with LED bulbs in them, they would work well for some of the lighting projects we discussed.

So, while out at the home improvement centers for other things, I took a peek in the light fixture aisle to see these 4/0 lights, but I did not see anything labeled that way. The Internet shows nothing, either. Has anyone else heard of these, or have I been sent on a snipe hunt?

  • @isherwood - Indeed; I noted this in my question, but I was hoping maybe I just have the search string wrong and someone might be able to tell me how to correctly type it.
    – bubbleking
    Feb 22, 2016 at 0:47
  • 1
    @isherwood - I think he might have been talking about something like this, which fits in a 4/0 octagonal junction box: amazon.com/Commercial-Electric-Recessed-White-Light/dp/…
    – bubbleking
    Feb 22, 2016 at 0:54
  • Interesting. Recessed lighting without cans. Does that fit the context of your discussion?
    – isherwood
    Feb 22, 2016 at 0:56
  • @isherwood - I think it does. I can't say for sure because he was making recommendations against my idea which involved using some LED strips in a closet. He said these would give a more pleasing effect.
    – bubbleking
    Feb 22, 2016 at 1:00
  • Back in the day, the 4" octagon boxes were called "four-oh" boxes. So, apparently he was talking about LED fixtures that fit into these boxes.
    – ArchonOSX
    Feb 22, 2016 at 15:14

1 Answer 1


"4O light" or "4/O light" appears to be jargon for a light fixture that can be mounted in a 4/O octagonal junction box.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.