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  • Grounding questions

    I have been reading this thread at another forum.

    http://www.dslreports.com/forum/remark,17584640

    I am not sure but I think some bad info is being put out. I know for a fact my home has only 1 ground rod and is not bonded to the water system. My home is a slab home with copper pipe run under the slab. My water service from the main is plastic.
    SSG, U.S. Army
    Retired
    K.I.S.S., R.T.F.M.

  • #2
    TOD,

    I read some of the posts and some knew what they were talking about and some didn't. It maybe that local jurisdictions have added or subtracted from the NEC.

    In ND, we are required to use the concrete encased electrode (Ufer) in new construction, plus bond the water system. In a service change we can use the main water line if it is metallic, plus a supplemental rod or plate. They have started to enforce the 25 Ohm rule, so if we can't prove that we have less than 25 Ohms to ground, we have to drive another rod. It is cheaper to just drive the rod, than it is to purchase the test equipment or have an independent testing agency come in and do it.

    Grounding and bonding is one the most misunderstood and misapplied sections in the code. I still learn something every time I read through it.

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    • #3
      Thanks for your reply. Is there a difference between overhead vs. an underground service. I have undergound here.
      SSG, U.S. Army
      Retired
      K.I.S.S., R.T.F.M.

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      • #4
        Tod

        Because people assume that their cold water pipes are well grounded, it's wise to make sure they really are. I would first recommend that you contact a licensed electrical contractor in your area and have your place checked, but here are a few things you can do on your own.

        1. Drive a 5/8" or 3/4" by 8 foot long ground rods into the ground and run a #4 bare copper wire from it to the copper cold water pipe near your entrance, but be sure to connect it to the house side of any shut off valves or your water meter. Try to keep grounding wires short.

        2. It's really hard to over ground your electrical system. I like to use two or three ground rods several feet apart near to where your main load center (breaker or fuse box) is and connect the ground rods together and then run the same piece of heavy copper wire (#4 gauge or heavier) to the grounding bar inside your load center.

        3. Inside your main load center, be sure there is a bonding (connecting) screw for the neutral bar. This makes sure that neutral is grounded, but you only do this at the point of electrical entrance.

        If you have any sub load centers (sub panels) you must run the neutral and ground as two conductors. Do not bond the neutral bar to the case or connect it to ground.

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        • #5
          Call before you dig applies to ground rods too

          Don't you have to be careful not to create ground loops if you have multiple grounds? They all need to be at the same potential (bonded together) or some circuits may have a ground reference that is elevated when compared to others.

          When you go to drive that extra ground rod or two make sure you are not driving it through a buried line or cable.
          • Some examples to watch out for:
          • heating fuel oil lines,
          • sewer and drain lines,
          • natural gas,
          • sprinkler piping,
          • buried power, TV, or phone cables,
          • and more.
          In most states I believe homeowners can call the location service to map out utilities for FREE. By the time you drive that 8 foot rod home, you are well past the depth of most of these, so watch out.
          "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
          John Ruskin (1819 - 1900)

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          • #6
            My house is fine. It was the thread starter that has the problem.
            SSG, U.S. Army
            Retired
            K.I.S.S., R.T.F.M.

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            • #7
              Is adding a ground to the water pipe really to improve the ground connection? I think it is to protect the home owner from shock. In my house the ground plate is tied to the copper and the copper is also tied to the gas pipe. There is no hope of improving the ground by bonding to the copper as the pipe that comes from the well into the house is plastic.
              I was here when the electrical was inspected and he wanted to see both copper and gas bonded to ground

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              • #8
                WBrooks. You are correct, connection to the water line is bonding. It is done with metal pipe only. It is required by code (at least it is here). It's purpose is to eliminate any voltage potential between the water/faucets and any appliance.

                We are not allowed to ground/bond to our gas lines here, though the connection is made through the appliances. All electrically powered appliances that connect to the gas system are grounded. This grounding will then connect and bond the gas line through the gas line connections. Of course this assumes metal gas lines.

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                • #9
                  Bob, Wayne and Thom

                  Good points

                  I didn't word it just right about using more than one ground rod. They do need to be bonded to each and I would use the same piece of wire. Ground loops do cause problems for sure. I hate seeing in older houses in my area where the only electrical ground connection is made to a cold water pipe and far from the entrance point. Our code now requires connecting the water sytem near the entrance and after the meter and any shut off valves to grounding rods.

                  Everyone does need to be careful when driving in a grounding rod. I've heard of people driving one through their basement wall A phone company tech told about hitting a large rock and having it make a U out of the rod. Someone must have really been hammering hard on that rod. (They use electric breaker hammers with an adaptor to drive them in) Do your calling and checking first. Above all else THINK before you just start driving things into the ground.
                  Last edited by Woussko; 01-11-2007, 12:33 AM.

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