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Community and Q&A

HDPE Electrical Conduit for Underground burial

fromPok | Posted in General Questions on

Can I use HDPE roll to run the main service line from transformer to meter box buried underground? Not sure what the code says. Here is an example of what I  mean. I can get these in 250 ft lengths and seems economical compared to regular PVC conduit.

Thank you.

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  1. Patrick_OSullivan | | #1

    Most of what's there is known as liquid tight, or seal tite, or other brand specific names. That's not suitable for direct burial.

    It's basically impossible to buy actual HDPE conduit (which is listed differently than the above in the NEC, and suitable for direct burial) through normal retail and in reasonable quantities.

  2. Matt_T | | #2

    Between the transformer and meter you should talk to the light company and do exactly what they require. They're likely to have specifications for the run, which may differ from the NEC. Our local Co-op requires PVC with 3' of cover and caution tape. The corporate poco runs direct burial themselves.

  3. Expert Member
    BILL WICHERS | | #3

    The listing at that link looks like a combination of what we call "loom" (a type of lightweight corrugated tubing used for cable management, not really conduit), and various types of liquidtite and sealtite flexible conduit. You don't normally want to bury significant lengths of flexible conduit, since it's too difficult to pull wires through (and I can't see any electrical contractor trying to install anything this way, and the utility would surely disallow it). The loom material is not suitable for burial at all, or even regular power wiring.

    The ""HDPE conduit" you'd need for burial is the stuff we use in the utility industry. This is a heavy wall pipe, a little like extra super heavy duty polyethylene sprinkler pipe. There are several types, sold as "SDR" (usually used for telecom work), and "Schedule xx" (usually used for power cable). The "Schedule xx" stuff is typically schedule 40 or schedule 80, which has to do with the thickness of the walls of the conduit. SDR stuff is similar, and we usually use SDR13.5 or SDR11 for telecom work.

    Anyway, what you'd need for power would have to be UL listed, and would typically be schedule 80, sometimes schedule 40. You would need at least 2" for service entrance, but I've seen utility companies require 3" in the past. I doubt they'd have a problem with the correct type of HDPE conduit being installed, since they likely use that same material themselves. You do need to use the right fittings to enter the meter can though. I would recommend you check with the utility's service planner prior to installing anything like this though, to make sure they are OK with it. Most electrical contractors will install PVC conduit for this application, which the utility industry usually calls "stick pipe".

    The other poster that mentioned this stuff typically being available only in pretty large quantities is correct. I don't think I've ever ordered a reel of less than 2,500 feet, and usually it's 5,000 feet to a reel. These are 6-8 foot reels made of steel pipe, and they get moved around on a special trailer. I'm usually using 1.25" to 2" pipe. You can probably find someone who can cut you a length of this stuff if you call around. I'd try calling underground utility contractors and ask if they can sell you some or recommend someone who can. Most commercial vendors will not want to sell cut lengths of this stuff. Note that this stuff will fight you too -- it will want to be a coil, not a straight line. You'll need to anchor it in some way if you install it in an open trench to keep it laying flat prior to closing the trench.

    HDPE conduit is very good stuff though, with an expected lifetime of centuries underground. It's much more durable than PVC conduit.


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