Bonding

Discussion in 'Electrical Forum discussion & Blog' started by Bgood, Jun 11, 2009.

  1. Bgood

    Bgood New Member

    Messages:
    3
    I am trying to finish a project which will not be inspected, but want to do all work to code.
    The service is to a pedestal (200A).
    Inside the pedestal is a 175A breaker that serves a subpanel on the exterior of the residence. Also inside the pedestal is a ground rod and a supplemental horizontal rod both attached to the ground bar.

    Questions:

    At the subpanel am I required to do any grounding/bonding?
    What about the r-bar sticking out of the slab?
    What about the copper piping 50 feet away in the bath and kitchen which never enters the ground (changes to PVC).

    TIA

    Bob
  2. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    Yes.


    If you are under the 2008 NEC then yes, you must connect to this with the proper clamp. Use a #4cu.


    Yes, you must bond the metallic piping system in the house. Since it is not metallic where it goes underground you can make this connection to a clod water pipe anywhere accessible.
    Again, use a #4cu for this bond.

    If you make these connections NO other electrodes or rods are required.
  3. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    You are also required to have both a ground and a neutral wire and the neutral wire at the residence can not be tied to the ground wire.

    I believe there is also a rule that if the residence is more than 25? feet away you have to have a ground rod at the residence as well.
  4. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    Depends. Under anything but the 2008 NEC a 3-wire feeder is still legal under certain circumstances. Something like this it would be pretty common to have a 3-wire feeder.

    Every structure with a feeder requires a grounding electrode. In this case it is the CCE (concrete encased electrode). NO ground rod is required.
    There is also no 25' rule like you mention.
  5. hiloelectric

    hiloelectric Electrical Contractor

    Messages:
    6
    Location:
    Seattle, Washington
    Petey, This install is on the Load side of a disconnect at the pedestal. Which means the house is only a subpanel and 4 wires would be required.
  6. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    Not always.
    If you have a 2005 or earlier copy of the NEC please see 250.32(B)(2).
  7. hiloelectric

    hiloelectric Electrical Contractor

    Messages:
    6
    Location:
    Seattle, Washington
    Okay I see what your talking about. However the water pipes, Gas, rebar and so on, in the house would be "Continuous Metallic Paths bonded to the grounding system in each building".

    I can see this applying to simple structures, (Garage, shed) but not a residence. Around here that would have never flown even when we were using the 2005.
  8. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    Oh, absolutely.

    I don't see why not. A house is a "building or structure" like any other, and fits the description in 250.32 like any other.
    I certainly do understand that local amendments will override the NEC if they exist.
  9. hiloelectric

    hiloelectric Electrical Contractor

    Messages:
    6
    Location:
    Seattle, Washington
    If you agree to this, then according to the 2005 you cannot run without a grounding conductor as it states in 250.32(B)(2) There are no continuous metallic paths bonded to the grounding system in each building or structure involved.

    That is how are inspectors interpret the code here.
  10. Terry

    Terry Administrator Staff Member

    Messages:
    15,004
    Location:
    Bothell, Washington


    That's why I love to backpack.
  11. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    That's right, no OTHER metallic paths, such as a water line, CATV or phone wire, etc.
    Nothing like this comes from the service pedestal to the house so there are no other metallic paths, so 250.32(B)(2) applies, so a 3-wire feeder is allowed.
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