Depth of cable burial for Ethernet and Coax?

Discussion in 'Electrical Forum discussion & Blog' started by ironspider, Mar 22, 2013.

  1. ironspider

    ironspider Member

    Messages:
    69
    Location:
    Michigan
    Greetings all, I know this is *technically* an electrical question but I think it's the closest I'm going to come to a perfect forum for asking this question.

    I have a barn/woodshop that is about 100' from my house. The barn has electrical and natural gas running to it so that's all fine. What I would like to do is run out some Ethernet and Coax cable for computing and Television. I found a number of various posts in various locations talking about burying power cables in the ground and whether or not they needed to be run in conduit and the like--but really nothing about these "data" runs.

    So, my question is just that: what would be the best plan for me to get the wire out to the barn? Direct burial cable not in a conduit? Burial in some form of PVC pipe? If so, how deep should each one be? Other things I'm not thinking of here?

    Climate info: I live in SE Michigan.

    Thanks!
  2. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,348
    Location:
    Cincinnati OH
    In pipe 24 inches deep min.
  3. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    Do you have a code reference for that?

    You can make it as shallow as you want and it can be direct burial. I'd go a foot deep.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    You don't want to be able to easily hit it with a shovel, or be stressed if you happen to drive over it. Since it's not carrying any electrical load, it's more about preserving it from damage than any safety issue. Not all cable is designed for direct burial, and if not, a conduit may be better for it in the long term. If your turns are correct, or you put in pulling elbows, you have the chance to pull new stuff in at some future time rather than running a new trench.
  5. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    I would only use direct burial grade even if it was in conduit. In my yard, I ran 300 feet of gel flooded CAT5 cable fished through 1/2 inch poly buried 6 inches deep and it worked well for years. I use a lot of rodent resist CAT5 cable at work, some of which is direct buried.
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,565
    Location:
    North Carolina
    Table 830.47
    Here we find that one foot is not deep enough unless it is in rigid metal conduit or PVC

    I would never for any reason go less than 18 inches on anything
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,251
    Location:
    Cave Creek, Arizona
    Data cables are seldom a "code" issue. The "rule of thumb" is that it should be buried at a depth that it is unlikely to be damaged. Metal conduit being stronger should be about 12" deep. PVC conduit CAN be damaged so it is at least 18" deep. Direct burial cable goes at least 22" deep to avoid be damaged by rototillers and the average digging process. For your purposes I would install conduit, because the odds are very good that you will eventually want to "upgrade" the installation which you could not do with "direct burial".
  8. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,510
    Location:
    Houston, TX
    It should be in PVC pipe just for its protection.

    You can put it in water pipe and lay it on the ground if you like. Or in a water hose for that mater.

    Low voltage , low current wire is of no danger to a digger.

    (This may depend on where you live, I use a sharpshooter 6" here and use PVC conduit, and a spare pull string. If you hit it you could be a DA.)

    There may be rules how close you can put it near your natural gas, if you start digging.

    Wireless may be another option.

    Good Luck.
  9. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    Yet another opinion. Although burial may not be necessary, you really done want the cable damaged. I would use the direct burial cable and bury it in conduit. I would probably rent a Ditch Witch (small size) that would trench 24" deep. Yes, that's pretty deep for something that may not even need to be buried, but why run the risk of damage? The DW would make short work of a trench that deep. PVC pipe would work. Thread a stout cord in the PVC to pull the line through. Maybe overkill, but not much extra expense to have the peace of mind that you won't have an accidental break.
  10. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,510
    Location:
    Houston, TX

    That is Good, and should only be done after the Gas line is located and marked.

    Cat 5 or 6 will not last very long unless it is in conduit that does not fill with water.

    RG6 or better should be used if the Coax run is very long.

    It is better to be safe than sorry.
  11. bluebinky

    bluebinky Member

    Messages:
    408
    Location:
    Santa Clara, CA
    I've never seen an underground conduit that wasn't full of water -- maybe hj has :cool:

    Also, if you have a sub-panel, make sure the neutral is not bonded...
    Last edited: Mar 24, 2013
  12. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    Maybe DonL doesn't know about direct burial grade gel flooded cable.
  13. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,185
    Location:
    NW Ontario, Canada
    Some folk think that conduit is better than direct burial. I can tell you that the frost action on a conduit filled with water is a lot harder than direct burial. I have first hand seen the result of what happens when a conduit filled with water freezes, expands, and rips wire or fiber optic cable apart.
  14. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,395
    Location:
    Yakima WA
    What am I missing here. Why would a PVC conduit flood with water? Each end surely would be in locations not subject to water, the underground PVV joints would be solvent welded, and if the conduit was buried deep enough so as not to be mashed by a vehicle driving over it, where does the water come from. It's rather like an irrigation line in reverse. Sorry guys, sometimes I'm a bit slow to catch on!
  15. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,510
    Location:
    Houston, TX

    I do know about direct burial grade gel flooded cable.

    And it will get damaged easier if it is not in conduit, and you need to go deeper if you use it.


    PVC should not fill with water, unless it is a Half Fast install.
  16. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    If the ends are open, condensation could fill it over time.
  17. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,510
    Location:
    Houston, TX
    Very True.

    If installed properly it should be sealed on both ends.

    Some installs even pressurize it, but that is a overkill for a home install.
  18. bluebinky

    bluebinky Member

    Messages:
    408
    Location:
    Santa Clara, CA
    I agree, except that the few dozen I've had to deal with were all full of water.

    Also, the NEC treats outdoor or buried PVC conduit as a "wet location" (not trying to say NEC applies to this situation...).
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