Connection to House Ground

Discussion in 'General Technical Questions and Answers' started by WA9UAA, Nov 8, 2019.

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  1. WA7ARK

    WA7ARK Ham Member QRZ Page

    And if you admit that wires have a finite resistance (typically 0.5 to 5mOhm per foot) and finite inductance (~3uH per foot), then there will still be a voltage difference between any two points in a practical circuit if they are bonded together with anything more than a few inches of wire.
     
    W8IXI and KA0HCP like this.
  2. KV6O

    KV6O Ham Member QRZ Page

    That's not practical. Yes, there will be voltage differences, but practically speaking if you bond correctly, they are much closer to being "GND" than if you have 2 ground rods separated by dirt. 10 Ground rods pounded into dirt are 10 separate "grounds", and in the practical sense, they will "see" greatly different conditions during a lightning strike. Bond them together and it's (theoretically) the same story, but the magnitude of "difference" (dV/dt) is much, much less, and it's a "ground system" at that point. Being practical and all.
     
    N0TZU likes this.
  3. WA7ARK

    WA7ARK Ham Member QRZ Page

    So, it is a matter of degree?

    Bingo!
     
  4. WA9UAA

    WA9UAA Ham Member QRZ Page

    Just to get back on track, can anybody tell me what kind of ground I have based on the conduit going from the meter box to the ground (dirt). How would I recognize a UFER ground?
    73,
    Rob
     
  5. N0IOP

    N0IOP Ham Member QRZ Page

    Hello Rob

    As noted upthread, electric codes and practices vary from one place to the next.

    It would be my guess that your ground wire is inside the conduit and the ground rod is buried, probably 6-12" below the soil, in the vicinity of the conduit. I suppose it is also possible that you have a Ufer.

    You could carefully dig down around the conduit and see what you find, possibly using a shop vac and (if necessary) a blunt, insulated tool of some kind to loosen the soil, and see what is there.

    Another fact to consider, is that the cable TV and telephone demark boxes to the left of the meter, should also have ground connections, and if you follow them down they will probably connect to the same ground the electric meter box uses.

    Ordinarily, in most places, if the neutral is bonded to ground at the meter box, there will be four wires (hot/hot/neutral/ground) going to the service entrance panel and the service entrance panel will not have its own ground rod. Again practices vary

    73
     
  6. WA9UAA

    WA9UAA Ham Member QRZ Page

    IOP, Thanks, maybe some discrete digging is in order, all I really need do is connect the grounds together, somehow.
     
  7. KV6O

    KV6O Ham Member QRZ Page

    Sure, but by this logic there no such thing as a 120VAC, 60Hz outlet. It's always relative.
     
  8. WA7ARK

    WA7ARK Ham Member QRZ Page

    I would expect the conduit to end a couple of inches below the surface of the dirt. There should be a fairly big bare Copper wire inside that conduit. That is what you would normally bond your other wire to...

    If there is a ground rod under your meter base, then digging a bit deeper should expose it. If you dig another six inches or so without seeing a clamp and the top of a ground rod, then you may have an Ufer, where the wire keeps going down to a poured concrete foundation under your house.

    In any case, clamp the #6awg coming from your antenna/coax ground(s) to that exposed Copper conductor coming out the bottom of the conduit. It'll be quite corroded when you find it...
     
  9. WA9UAA

    WA9UAA Ham Member QRZ Page

    Thanks ARK, now looking for an open type of clamp that I can slip on something. ;)
    73,
    Rob
     
  10. NN4RH

    NN4RH Premium Subscriber QRZ Page

    I lost track of the thread for awhile but if I understand you're wanting to connect wire to wire, go to Lowes or HomeDepot and look for "Split Bolt" connectors. Bronze. Rated for direct burial.
     

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