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Digging around buried electrical - how deep; how safe?

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  • Digging around buried electrical - how deep; how safe?

    I know where the buried electrical runs behind my house from when it was marked a few years ago. I *think* it's supposed to be at least 18 inches down and running through a conduit.

    I'm starting to build a raised garden right over where the line runs, and I need to dig a few inches for the first course of the retaining wall. Of course I'll be digging carefully, and I'm just using stacking concrete wall blocks -- just in case we want/need to move the garden later.

    So just how careful do I need to be? I'm not using any heavy machinery (just shovels) and I'm digging only a few inches. Is there any reason to believe I may hit or break the conduit?
    online at http://www.theFrankes.com
    while ( !( succeed = try() ) ) ;
    "Life is short, Art long, Occasion sudden and dangerous, Experience deceitful, and Judgment difficult." -Hippocrates

  • #2
    your electrical utility company hates emergency restoration of power and hates even more when people get killed or hurt. Expensive emergency crews, bad publicity, lawsuits, irate customers, all those things.

    They will be more than glad to come out in advance to your doing any POSSIBLE work and mark where the lines lie and probably can give you advise on how deep they are.
    Call them and see.
    Last edited by LCHIEN; 03-22-2008, 10:37 AM.
    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ - http://www.sawdustzone.org/forum/dis...sked-questions

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    • #3
      Thanks for the input -- I'll give them a call to be sure.

      Just to be clear, I know exactly where the lines are from when they were marked a few years ago (photos and in-ground landmarks) -- I just don't know how deep or how they're protected, so I don't know how carefully I need to dig (even if the lines are re-marked -- e.g. full force straight down versus archaeologist-style with a dental pick and a toothbrush)

      I'm guessing they're in the same PVC conduit that I see coming out of the ground at the house, but I've never seen the actual underground lines before...
      online at http://www.theFrankes.com
      while ( !( succeed = try() ) ) ;
      "Life is short, Art long, Occasion sudden and dangerous, Experience deceitful, and Judgment difficult." -Hippocrates

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      • #4
        I wouldn't tell them you know where it is. well, its always interesting to see if they mark the same place... :-)
        and you can ask them exactly what to expect if you do hit it with a shovel or whether they're oK with that and all your other questions. I'm sure they know exactly what it looks like (underground lines).

        And the service is free.
        Loring in Katy, TX USA
        If your only tool is a hammer, you tend to treat all problems as if they were nails.
        BT3 FAQ - http://www.sawdustzone.org/forum/dis...sked-questions

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        • #5
          How close to the house is it? A rule of thumb I use, is closer to the house/building, the more careful you need to be as it is coming UP towards it.

          Otherwise, not too sure, I would at first treat it like your trying to save the sod, prod around with something non conductive (sharp stick), then dig.
          She couldn't tell the difference between the escape pod, and the bathroom. We had to go back for her.........................Twice.

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          • #6
            We do a lot of digging for my realm of construction.

            There are 1 Call utility numbers to call. Call them. They will mark it and may dig it up.

            Use a fiber glass shovel and be careful, don't go at it hard. Even a shovel can cut pvc, I've seen it and done it.

            NEC is 18" of cover, but that's not always adhered to.

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            • #7
              Originally posted by gjat View Post
              We do a lot of digging for my realm of construction.

              There are 1 Call utility numbers to call. Call them. They will mark it and may dig it up.

              Use a fiber glass shovel and be careful, don't go at it hard. Even a shovel can cut pvc, I've seen it and done it.

              NEC is 18" of cover, but that's not always adhered to.
              I'll second what he said. If you happen to cut the line with a shovel, most utility companies will likely charge you for fixing it. I think most underground wiring will be found to be in PVC in this day and age.

              Ed
              Do you know about kickback? Ray has a good writeup here... http://www.bt3central.com/articles/l...p?ArticleId=85

              For a kickback demonstration video http://www.metacafe.com/watch/910584...demonstration/

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              • #8
                Around here, electrical services to house and even the mainline are neither in conduit. They do attach a small piece of sweep when it comes up out of the ground. I have dug up a ton of electrical feeds and they are covered with a VERY heavy jacket and it is unlikely you would break it with a shovel. But most of those are newer services, I don't know how old yours is. Go slowly and carefully and if you only have to dig a few inches you should be fine. Always err on the side of caution though and don't go chopping at any "tree roots".

                The locates that others have advised would be a good idea also. Don't trust your memory of old locates or even if you remember them perfectly don't trust the guy who done them. Around here they can be off up to 18" in either direction and still be considered to have been done properly. I have personally hit utilities with backhoes and excavators that were off by 5'. The flash of an arc welder has nothing on a 330 Cat digging into a 7KV line.

                If you ask for hyper-accurate locates (that is the name they go by around here) they can usually tell you the depth +/- tolerance, but they also charge more for that here.
                "A fine beer may be judged with just one sip, but it is better to be thoroughly sure"

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                • #9
                  I used a garden hoe once. I pretty much knew the route and I just used the hoe to scrape along until I got to the wire. The insulation was pretty thick and tough, the hoe was dull.
                  Last edited by Daryl; 03-22-2008, 04:47 PM.
                  Sometimes the old man passed out and left the am radio on so I got to hear the oldie songs and current event kind of things

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                  • #10
                    Even though you know whre the wires were marked the last time there is probably a requirement to call and have them remarked again. This also limits your potential liability if you would accidently cut or nick the wire.

                    I don't think you're going to find it in a pvc conduit. It's much cheaper to use wire rated for direct burial.
                    Rick

                    A sailor travels to many lands
                    Any place he pleases
                    And he always remembers to wash his hands
                    So's he don't gets no diseases
                    ~PeeWee Herman~

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                    • #11
                      Originally posted by LCHIEN View Post
                      I wouldn't tell them you know where it is. well, its always interesting to see if they mark the same place... :-)
                      Now that's a scary thought! jonmulzer mentioned 18" off in either direction is a possibility, so this will be a good experiment!

                      Originally posted by LinuxRandal View Post
                      How close to the house is it? A rule of thumb I use, is closer to the house/building, the more careful you need to be as it is coming UP towards it.

                      Otherwise, not too sure, I would at first treat it like your trying to save the sod, prod around with something non conductive (sharp stick), then dig.
                      Probably about three feet in the first location, and twelve feet in the second. Both places, though, are my "low points" for the wall, so I'm basically just planning to remove the sod... I might even actually build up a bit with some dirt...

                      Originally posted by jonmulzer View Post
                      Always err on the side of caution though and don't go chopping at any "tree roots".
                      Yeah, no kidding!!

                      Thanks for the great input, guys!
                      online at http://www.theFrankes.com
                      while ( !( succeed = try() ) ) ;
                      "Life is short, Art long, Occasion sudden and dangerous, Experience deceitful, and Judgment difficult." -Hippocrates

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                      • #12
                        I would call and have them come out and mark the lines. Not just electrical lines, but ALL lines. You might have cable, phone, etc in the area that you didn't know about.

                        In my past experience electric is NORMALLY a good foot+ deep. I have seen cable and phone only a 1-2 inches below ground. Cut thur a cable line once just putting the shovel in the ground. When they check for the electric lines they should be able to tell you how deep the lines are if they have the right equipment.

                        As said before if they mark and you damage the line verses they don't mark and you damage the line, are to totally different things in lawsuits!

                        1 thing to keep in mind, if they have to (re)dig something down the road they will NOT care what is in their way!
                        Ric

                        Plan for the worst, hope for the best!

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                        • #13
                          Originally posted by TheRic View Post
                          1 thing to keep in mind, if they have to (re)dig something down the road they will NOT care what is in their way!
                          Yeah, this is why we opted for those stackable concrete blocks as opposed to a more permanent wall. If we have an hour's notice, we can just move the wall out of the way. It's a gamble, though.

                          I had a problem when they came in to bury the cable (TV) line. I was there when they laid it out and made sure it was laid out to avoid underground drainage. When they got there with the trench digger, though, they just ignored the layout, made a beeline to the cable box out back and as a result cut straight across the drain. After two calls and two empty promises that it would be repaired, I finally got them to agree to deduct the repair cost from my monthly bill. It was a real hassle, though....
                          online at http://www.theFrankes.com
                          while ( !( succeed = try() ) ) ;
                          "Life is short, Art long, Occasion sudden and dangerous, Experience deceitful, and Judgment difficult." -Hippocrates

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