Running a ground wire in conduit to plumbing

Discussion in 'Electrical Forum discussion & Blog' started by Juan for the road, Aug 10, 2008.

  1. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    I would like to run a ground wire in conduit(with other conductors) to a surge protected device.How can I go from the conduit to a plumbing ground clamp?
  2. Chris75

    Chris75 Electrician

    Messages:
    608
    Location:
    Litchfield, CT
    you wanna explain exactly what your trying to do and accomplish? mostly the accomplish part.
  3. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    I need to run a 8ga ground to an electronic control panel for it's required surge protection.Requires a ground rod or plumbing meter ground.I want to run this ground and the hot,neutral conductors in the same conduit,as the feeds will be passing past the water meter on the way to the electronic control panel anyway.

    Just want to be sure of a code compliant way to Tee out of the conduit to make this connection to the water meter ground clamp
  4. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    The bonding conductor that is to land on the grounding electrode system does not have to be installed in a raceway unless it is subject to physical damage.

    Should you decide to install the conductor in a pipe and that pipe is a metal raceway then the metal raceway will need to be bonded to this conductor on both ends. This can entail a lot of extra work and expense.

    If in your opinion the conductor needs to be protected then install it in a nonmetallic raceway and the requirement to bond to the raceway is lifted.

    By installing a junction box you can then exit the raceway via the box.
  5. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    Yes physical harm of the wire is a concern.
    The feeds are to feed out of a GFCI receptacle in a surface mounted 4" steel box.

    Am I permitted to run NMT(PVC) conduit straight out of this box?

    This box is located in a mechanical room with fire-rated drywall and doors and the surface mounted conduit is all EMT.

    I would like to transition from EMT out of this room to NMT,but I would prefer to do this outside of this room.

    Yes,the water supply for the ground wire is in close proximity to the GFCI receptacle/steel box.
    Last edited: Aug 11, 2008
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    Is this residential or commercial?
  7. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    Rez...how would the codes differ depending?
  8. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    The codes would be no different for the type of installation that you are doing. The differences would be are you killing only yourself or a bunch of other people. By simply reading your post it is very obvious that you are way over your head with what you are installing.
    It is okay in most areas of the United States for a homeowner to endanger their own lives and the lives of their families as long as they are making installations in a home that they own but they are not allowed to make installations in rental or commercial properties.
  9. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    I appreciate your concern.
    Let me be specific at this point.
    I would like to come out of a 4" box containing a GFCI protected receptacle(which is wired in series with 3 other receptacles).Everything is surface mounted,run in 1/2" EMT.Located in a fire-rated mechanical room.I plan on coming straight down the wall,from that 4" steel box with 1/2" EMT containing 3 wires:hot,ground and neutral,all 12ga THHN.

    The EMT will then procede to a box approx 12" from the floor,where an 8ga THHN wire will enter the box,having been clamped to the copper water supply before the water meter(located about 18" from the box).I will clamp the 8ga ,where it enters the box with a NM butterfly style clamp(probably wont clamp much actually).

    At this point,the EMT will travel down thru the floor in a tightly drilled hole,sealed with fire-rated caulk, to the crawl space beneath.I will run the EMT into a steel 4" box containing the 4 wires.I would like to,at this point,come out of the steel box with NMT(PVC),1/2" and procede to the outside to another box,mounted to the exterior of the house,a weather proof plastic box.Then from there,1/2" NMT to the Control Panel(with a max draw of 1.5a).Control Panel is hard-wired.

    The 8ga,is specifically for surge suppression.I could set a dedicated ground rod,however the sandy/gravelly soil makes for an unreliable ground here.I much prefer a copper water supply ground.

    NMT will have to 90* once in the crawl space,will use the proper sweep.Straps every 32".

    I will total the individual wire fill to be sure that 1/2"conduit is OK.
  10. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    You say the #8 is only for surge suppression. From that I infer that you have a code-compliant Grounding Electrode System and the #8 you are asking about is not the Grounding Electrode Conductor.

    Since you are running this in EMT, the EMT is/should be bonded to the grounding system running back to the service, maybe through a subpanel or maybe not. EMT is an acceptable Equipment Grounding Conductor so it doesn't require a separate grounding conductor (a "green wire") for the circuit.

    I am not aware of any code provision that prevents you from running an additional #8 copper conductor from any piece of equipment to any other piece of metal in the facility, except that it may not be connected to an ungrounded (hot) conductor or to the grounded conductor (neutral). I also don't know of any provision that would permit you to omit the equipment grounding conductor ("the green wire") from any circuit that you install.
  11. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    Here is the code references;

    ARTICLE 285 Surge-Protective Devices (SPDs), 1 kV or Less

    285.28 Grounding Conductor Connections and Enclosures.
    Except as indicated in this article, SPD grounding connections shall be made as specified in Article 250, Part III. Grounding conductors installed in metal enclosures shall comply with 250.64(E).

    250.64(E) Enclosures for Grounding Electrode Conductors. Ferrous metal enclosures for grounding electrode conductors shall be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode and shall be securely fastened to the ground clamp or fitting. Nonferrous metal enclosures shall not be required to be electrically continuous. Ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made electrically continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor. Bonding shall apply at each end and to all intervening ferrous raceways, boxes, and enclosures between the cabinets or equipment and the grounding electrode. The bonding jumper for a grounding electrode conductor raceway or cable armor shall be the same size as, or larger than, the enclosed grounding electrode conductor. Where a raceway is used as protection for a grounding electrode conductor, the installation shall comply with the requirements of the appropriate raceway article.

    For more help see this
  12. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    Thank you for the code refs,pretty much answers it.
    Yes,the 8ga is solely for surge protection,to protect the electronics,apart from the electrical.

    The enclosure itself,of the control panel, is plastic,rated indoor/outdoor.

    I will feed the panel from the GFCI receptacle,out to EMT down to the crawlspace to a steel box,grounded with the EGC. I will then transition to !/2" PVC conduit to the outside and to the enclosure.

    I'm going to clamp the 8ga to the water supply in the crawlspace to simplify things and run it in a seperate 1/2" conduit,it's a short easy run.Conduit is just neater and takes the guess work of what the wire is,in the future.

    Is it OK to just bring the 8ga from the clamp directly into a piece of conduit,without any box or othe transition?

    If I had a situation where I had a NM cable,and wanted to get it into PVC conduit for protection purposes,say near an attic scuttle,can I just put it in there(provided it meets the conduit fill table)?
  13. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    If you install this #8 in EMT and a metal box and do not bond it back at every point where in enters and leaves the metal raceway and enclosure then in the event of a surge due to lightning the #8 is useless and the surge protector will do nothing to protect anything.

    [​IMG]
  14. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    FYI - The reason both ends of the conduit must be bonded is to prevent what is called "inductive choke". These gizmos or anything behaving in this manner restrict alternating current. And home electricity is alternating current. So you want your house current to be able to "flow" through the ground wire unimpeded.

    Here is more on this...
    http://en.wikipedia.org/wiki/Choke_(electronics)
  15. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    If I run the #8 in PVC conduit (for protection),I am OK?
  16. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    Right. You don't have that potential "choke condition" with plastic conduit.

    But if this is going to an electronic gizmo which is sensitive to outside interference, note that wiring can pick up electrical "noise" and feed this into the device. This is like driving a car under electrical lines listening to AM radio. You get that buzzzzz on the radio. Metal conduit will keep outside noise out of the wiring. This idea is called a "faraday cage"
    http://en.wikipedia.org/wiki/Faraday_cage

    So it would be best to use metal conduit, but probably will not matter. Here are all the bonding bushings you could ever hope for...
    http://www.electriciansupplies.com/...9/Grounding_&_Bonding_Bushings_-_Bushings.htm

    FYI - If you are getting this inspected, might want to discuss what you plan to do with an electrical inspector BEFORE you do any work. These guys usually have office hours where you can go and ask questions. Take plenty of pictures of the areas where you plan to do this work. Then the electrical inspector can see any potential problems. And this will minimize your having to re-do anything.
    Last edited: Aug 12, 2008
  17. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    P.S. There is another thing called a "Central point of ground". (lots of stuff to this grounding business! :) ) Anyway the idea is to have all ground wires connected to one central ground rod or multiple ground rods interconnected in the same area.

    Doing this prevents "ground loops". More on that here...
    http://en.wikipedia.org/wiki/Ground_loop_(electricity)
  18. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    Without entering any type of metal box it would be okay but if you enter a metal box then that box must be bonded to the #8 where it enters and exits and a romex connector will not work for the bonding.
  19. Juan for the road

    Juan for the road New Member

    Messages:
    17
    Location:
    Northeast,USA
    Along these lines,if I were running multiple wires thru PVC conduit for physical protection,then had the PVC conduit terminate into say,an 8X8 metal box containing (3) 12/2, (2) 10/3,and (1) 8/3,all Romex...What grounding would be required for the metal box?
  20. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,529
    Location:
    North Carolina
    This metal box will need to be bonded to the largest equipment grounding conductor. This will be a #10 that is either in the 10/3 or the 8/3 cable.

    I don’t understand just how you are installing these cables. If this box is a junction box then there should be an even number of each cable unless you are pulling the cables straight through the box without a splice or joint.
    In this case either the 10 or the 8 will need to be opened to access the equipment grounding conductor.
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