After new siding was installed on the house, there is a 1-1/2"-thick wooden spacer between the electrical box for an outside light and the location of the light. In my prior experience, the electrical box was always placed snugly next the fixture. How does one meet electrical code when there is a wooden spacer?

The photo shows the Hardie board siding (yellow) with a 1.5-inch-thick wooden block (white) with a roughly 3.75-inch-diameter cylindrical hole. At the top of the wooden block is metal flashing (dark gray). Inside the hole, you can see some Tyvek housewrap (white with blue writing) and the electrical box (gray). The lighting fixture is supposed to go on the outside of the wooden block.

Is it OK, under electrical code, to just stretch the wires from the electrical box to the fixture and install the light fixture on the outside surface of the wooden block?

The house is in northern California, USA, in the San Francisco Bay area.

enter image description here

While researching this, I found two questions about wall-mounted outdoor lights but both have answers (here and here) showing the electrical box snugly meeting the light fixture.

  • 2
    I thtink they make box extenders, but not sure if they're legit for a wet location.
    – SteveSh
    Commented Mar 31, 2020 at 0:04
  • 2
    2nd the box extender. Also don't know the code related to exterior use. A sparky will be by shortly and give us the lowdown
    – Ack
    Commented Mar 31, 2020 at 0:13
  • I dont really know about codes but I have faced similar situations. I simply use really long bolts/screws. It mostly depends on the mouting hardware for the fixture, if supplied.
    – Jahaziel
    Commented Mar 31, 2020 at 0:21

1 Answer 1


Yes, there is such a thing as a weatherproof extension ring

While you can't just extend the wires out beyond the box to the fixture (what if a splice failed and tried to light things on fire?), the good news for your situation is that weatherproof extension rings do exist! Ask your local supply house for a Hubbell (Bell/Raco) 5363-0; this will give you 1.5" of extra box depth, which should be just enough to deal with your spacer board.

a Hubbell 5363-0

  • 2
    But the original box in the wall looks to be non-weatherproof - just a common octagon box, from what I can see. With nothing to seal to, does a weatherproof extension ring do anything at all here .vs. a plain-jane extension ring?
    – Ecnerwal
    Commented Mar 31, 2020 at 13:16
  • @Ecnerwal That's an interesting point: as the photo shows, there are holes in the back of the octogon box and exterior-wall thermal insulation can be seen behind the holes. (The octagon box wasn't mine: it was installed by a commercial electrician who has since disappeared, leaving the work incomplete.) Separately, ThreePhaseEel, I ordered the ring you recommended.
    – John1024
    Commented Mar 31, 2020 at 20:22
  • 1
    @Ecnerwal -- the issue with a plain ring is that there'll be no way for the fixture housing to seal against it. I agree that the indoor octagon box wasn't quite right, but I suspect that if you used a plain extension ring (vs weatherproof), you'd have much more water intrusion on your hands... Commented Mar 31, 2020 at 22:28

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