I have a terraced backyard with 3 retaining walls, each about 4' high. One is poured concrete, the other two are wood (PT 3x12). I am looking to add some outlets to the backyard from an existing receptacle on the back of the house. This will be one circuit with 3 individual thwn-2 12 AWG wires: hot, neutral, ground.

I'd like to bury 3/4" pvc conduit, pop out in front of the retaining wall and then go into the next terrace by going through the wall instead of over the top and back down. The hole I drill in the wall would be at least 1". I'm choosing 3/4" conduit in case I ever want to add a 2nd circuit, or cat-6 ethernet cable, in the future.

Any issues with my approach?

Mild calif winters here, no snow or frost concerns.

  • 2
    With limited exceptions, you'll need a different/separate conduit to be able to run ethernet and comply with code.
    – Ecnerwal
    Nov 20, 2020 at 19:08
  • good to know. I can always use a powerline adapter instead
    – dabi
    Nov 20, 2020 at 20:24
  • 1
    Even with 1/2” you can run quite a few circuits. Pvc has to be birdied deeper than rigid in some cases purchasing rigid is worth it. I recently ran a circuit outside in rigid my own home for this very reason a 1/2” pipe only a 7” trench pvc 19” trench
    – Ed Beal
    Nov 20, 2020 at 22:11

1 Answer 1


Structurally it’s not an issue, even if you happen to drill through a rebar in the concrete retaining wall.

However, if you’re holding back subsurface water behind the concrete retaining wall, the hole could allow water to squirt out.

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