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I have a single 20 amp circuit coming out of PVC conduit buried 18" in the ground into an LB connector that enters a detached garage. I'd like to enter the garage at 12" or less above ground, is there any minimum height restrictions?

On the inside side opposite the LB connector, I'd like to place a power cutoff switch ( a simple single pole switch ) inside an electrical box so the switch would be off the garage floor by about 12" as well. From this box I'm rising with conduit to another box with a receptacle at a normal 4' or so height.
Does this seem okay?

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  • The older you get, the harder it is to reach down to 12 inches above the floor. Just something to think with the switch.
    – crip659
    Commented Apr 16, 2022 at 14:36
  • If it is not buried , it will be in the way , someday.
    – blacksmith37
    Commented Apr 16, 2022 at 15:56

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The expansion joint sets the practical limit

Note that in any situation where you need to use an expansion joint in your stub-up, the length of your expansion joint will set the practical limit on how low you can go. Generally speaking, prefabricated PVC expansion fittings are 10" long in a "neutral" (halfway between contracted and extended) position, but you'll likely need a couple of extra inches to transition from the expansion joint to the box, unless you have one of the Carlon bell X thread (vs bell X bell) expansion joints.

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  • Transition joints are not needed or required with such a short distance above ground unless someplace like the Mohave where you regularly have a 75 deg change in a day or worse.
    – Ed Beal
    Commented Apr 16, 2022 at 14:20
  • @EdBeal -- not for straight up thermal expansion, no, but they can make sense in places subject to ground movement for other reasons (frost heaving for instance)
    – ThreePhaseEel
    Commented Apr 16, 2022 at 21:22
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You can bring the conduit in at whatever height you want but be aware you can use schedule 40 in the trench bottom as you come up you need to change to schedule 80.

As far as minimum heights there are none in code there are maximums but as crazy as it sounds it could be at 6” from the floor. I have worked on load centers that was less than a foot off the ground where the owner was saving a few bucks by putting the panel in low and bottom fed (upside down)it met code but caused a lot of headaches.

If you are using a standard snap switch for your disconnect it needs to be an on/off and have the OFF position stamped in the switch (so no 3 way switches).

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  • Thank you, I did not know about the schedule 80, requirement above ground. Good thing I haven't glued it yet! Can the transition sweep from horizontal to vertical remain schedule 40?
    – user43769
    Commented Apr 16, 2022 at 1:57
  • Yes, because it's buried and protected from damage. The Sch 80 pipe is much more damage resistant than the Sch 40 and is required where the pipe would be subject to physical damage, such as hitting it with the lawn mower.
    – FreeMan
    Commented Apr 16, 2022 at 12:03
  • @freeman right idea backwards schedule 80 is required where it could be damaged by the mower, I have tried to find schedule 80 sweeps in the past without much luck and that was at electrical supply’s like platt, big in the PNW. Yes they can be found but the few times I needed them no one stocked them so I used 40 and it passed but note from experience inspectors don’t check pro’s as close.
    – Ed Beal
    Commented Apr 16, 2022 at 14:30
  • My statement was based on the presumption that the sweep would still be underground, transitioning from the horizontal run at 18" of cover to the vertical which would penetrate the surface with Sch 80. Therefore, the Sch 40 sweep, still underground, would be fine. May not have said that as clearly as I meant it.
    – FreeMan
    Commented Apr 17, 2022 at 11:50
  • By code the schedule 40 has to be at 18” or below as the op stated an 18” trench as soon as the sweep comes up it should be 80, and re read the last line it states schedule 40 is required where the pipe is subject to physical damage , it’s schedule 80 not 40.
    – Ed Beal
    Commented Apr 17, 2022 at 15:24

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