I've installed a number of strip lights in my garage to replace the single incandescent fixture on the ceiling. They all use a 3-prong plug, not hardwired. I want to replace the incandescent fixture with a junction box containing an duplex receptacle, then branch out to other receptacle boxes to serve each light.

The strip lights, receptacles, and wiring are all done, but I ran into a mounting issue with the main junction box. Is it possible (or correct) to overlay an extension to the octagon box? The octagon box is recessed deep, about 1" below the drywall. I need the box to protrude to allow the side knockouts to supply wire to the neighboring receptacles. Home stores don't seem to have any adapter between the two types. An octagon extension with a cover would fit, but I'd need to stack two of them to get the knockouts to clear the drywall and that doesn't seem correct.

Or, should I rip out the octagon box and install an "old work" junction box?

  • 2
    If you could post a photo it would help.
    – ChrisF
    May 31, 2011 at 19:14
  • 2
    Are you looking for something like this, or do you need something to extend the box to be flush with the drywall? Something like this
    – Tester101
    May 31, 2011 at 19:42
  • 1
    Check your local codes, you might need to add a GFCI as the first receptacle in line. It is code in most places that garage receptacles are to be GFCI protected, so you'll have to feed all the other receptacles from a GFCI.
    – Tester101
    May 31, 2011 at 19:44
  • I believe I have a GFCI breaker already on that circuit. And no to the flush mounting. The box has to protrude in my explanation.
    – spoulson
    May 31, 2011 at 20:42
  • So the current box is in the wall, and you need to mount one on the wall? Is there enough slack in the wire to move the box out? A picture would really help here.
    – Tester101
    Jun 1, 2011 at 12:14

1 Answer 1


You might be able to get away with mounting an extension to the existing box, then using a box cover with conduit knockout and a cable clamp you could run your cable out the front of the box instead of through the side knockouts.

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  • I like this approach. I'll try it out.
    – spoulson
    Jun 2, 2011 at 10:56

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