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    Labor's Avatar
    Labor Posts: 34, Reputation: 1
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    #1

    Oct 6, 2008, 01:01 PM
    Grounding questions
    Can anyone take me through the steps for grounding my house? On the outside of the house, I've mounted a new meter socket rated for 200 amp service, and next to it, I have a 200 amp, exterior main breaker. It is not a combo unit. The meter is separate from the main break and the two boxes are connected with a 3" galvanized nipple using bonding bushings. Inside the house, about 11 feet away, I have a 200 amp main breaker panel serving as a sub-panel. I will be installing 2 appropriately-sized ground rods below grade at least 6 feet apart under the drip edge of the roof. I have #4 copper for the grounding conductor as required by code. I also have 2 acorn clamps that are rated for burial. I will be putting the clamps on the ground rods before I drive the rods into the ground. I understand that the #4 grounding conductor needs to be continuous between both rods, and connected to the rods using the acorn clamps, but I don't know whether I should be running it to the meter or the exterior main breaker box. I assume that it is the meter socket, but assumptions aren't good enough when it comes to electricity.

    (2) Also, my water comes from a well. Galvanized pipe that is buried underground travels from the well to a well pump that is located in a pump house just outside of my back door. From the pump house, the water travels through plastic piping through a concrete block foundation wall underneath the flooring of the house and once it is in the house, the plastic pipe is converted to copper with a union. Code requires that I bond the neutral bar to the water system, if copper or galvanized piping is used. I assume that this means that I need to bond the neutral bar of the exterior main breaker to the water pipe. First, is that a correct assumption? Second, if so, what water pipe do I bond to -- the galvanized pipe that comes out of the well and is buried in the ground or the copper "water system" in the house? Third, I am planning on using #4 copper for this as I understand that to be consistent with NEC requirements. Can someone confirm that?
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
    Electrical & Lighting Expert
     
    #2

    Oct 6, 2008, 02:19 PM
    OK, first part.
    What you are describing is fine.
    Small details: you do not need #4cu to a ground rod (or two) alone. #6cu is all that is required for this. NEC 250.66(A)
    Also, the connection to the first rod must be continuous, but the second rod is a supplemental electrode. The wire is not required to be continuous to it, but it is usually easiest to simply loop the wire from one to the other.

    Second part, both grounding electrode conductors and water bonds must go to the service disconnect. In your case this is the disconnect outside.
    IF your water pipe entering the house is metallic, then you must connect to it within 5' of where the pipe enters the house. This wire also serves as the water bond.
    If the water pipe entering is plastic then you just have to run a water bond to any accessible spot on a cold water pipe.
    This wire is sized according to T250.66.
    Labor's Avatar
    Labor Posts: 34, Reputation: 1
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    #3

    Oct 6, 2008, 02:41 PM
    Quote Originally Posted by stanfortyman View Post
    OK, first part.
    What you are describing is fine.
    Small details: you do not need #4cu to a ground rod (or two) alone. #6cu is all that is required for this. NEC 250.66(A)
    Also, the connection to the first rod must be continuous, but the second rod is a supplemental electrode. The wire is not required to be continuous to it, but it is usually easiest to simply loop the wire from one to the other.
    Second part, both grounding electrode conductors and water bonds must go to the service disconnect. In your case this is the disconnect outside.

    Stan, I can't speak for the NEC on this, but the #4 GEC is required by local code because it is 200 amp service. So, from the ground rods, do I run the #4 to the exterior main disconnect? To be clear, there will be no GEC run to the meter?

    IF your water pipe entering the house is metallic, then you must connect to it within 5' of where the pipe enters the house. This wire also serves as the water bond.
    If the water pipe entering is plastic then you just have to run a water bond to any accessible spot on a cold water pipe.
    This wire is sized according to T250.66.
    The pipe that is actually entering the house is plastic. Once inside the house, the plastic converts to copper. Are you saying that I should bond the neutral bar in the main service disconnect -- which is outside -- to the nearest cold water copper pipe inside the house? Can I use the #4 to do this? Do I need a bonding jumper between hot and cold pipes under the house or at the water heater?

    Lastly, correct me if I am wrong, but my understanding is that ground bar and neutral bar at the main breaker are bonded, but the ground bar and neutral bar at the sub panel in the house are not bonded? The sub panel in the house will actually receive a #4 ground from the main disconnect, along with 2 2/0 hotts and the 1 2/0 neutral that I've already installed.
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
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    #4

    Oct 6, 2008, 05:18 PM
    Quote Originally Posted by Labor View Post
    The pipe that is actually entering the house is plastic. Once inside the house, the plastic converts to copper. Are you saying that I should bond the neutral bar in the main service disconnect -- which is outside -- to the nearest cold water copper pipe inside the house? YES
    Can I use the #4 to do this? YES
    Do I need a bonding jumper between hot and cold pipes under the house or at the water heater? NO

    Lastly, correct me if I am wrong, but my understanding is that ground bar and neutral bar at the main breaker are bonded, but the ground bar and neutral bar at the sub panel in the house are not bonded? TRUE
    The sub panel in the house will actually receive a #4 ground from the main disconnect, along with 2 2/0 hotts and the 1 2/0 neutral that I've already installed.CORRECT
    ..........
    Labor's Avatar
    Labor Posts: 34, Reputation: 1
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    #5

    Oct 7, 2008, 09:53 AM
    Quote Originally Posted by stanfortyman View Post
    ..........
    2 more follow up questions stanfortyman (or anyone else):

    (1) My reading of the NEC requires continuity (i.e. no splicing) in the GEC between the ground rods and the main breaker, does this prevent me from running two GEC's -- one from neutral/ground bus in main break to nearest accessible copper water pipe and another from the neutral/ground bus in main to the 2 ground rods? In other words, must I run one continuous line from panel to water pipe and then to the ground rods, or can I do it in two runs of #4 copper? I was planning on doing this in 2 separate runs (one from panel to water pipe and one from panel to ground rods), but I am concerned about the continuity requirement of the NEC.

    (2) I am surprised that I won't be grounding to the meter box. Is this because the neutral hookups in the meter box are bonded to the box?
    stanfortyman's Avatar
    stanfortyman Posts: 5,598, Reputation: 279
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    #6

    Oct 7, 2008, 11:54 AM

    1) We typically run two wires. It is much easier to run a water bond separate from the ground rod wire.

    2) This is a power company thing. Since it is locked with their lock the inside of the meter pan is their territory and they dictate what can and cannot be terminated inside.
    Some used to have the ground rod wire terminate inside the meter pan, but I have not heard of this being done in quite a few years. That is why you will see this from time to time.
    Labor's Avatar
    Labor Posts: 34, Reputation: 1
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    #7

    Oct 7, 2008, 12:07 PM
    Quote Originally Posted by stanfortyman View Post
    1) We typically run two wires. It is much easier to run a water bond separate from the ground rod wire.

    2) This is a power company thing. Since it is locked with their lock the inside of the meter pan is their territory and they dictate what can and cannot be terminated inside.
    Some used to have the ground rod wire terminate inside the meter pan, but I have not heard of this being done in quite a few years. That is why you will see this from time to time.
    Thanks stan. Anything to prevent me from running both GEC's in 1 or more conduit raceways? If no, can I use plastic pvc and run it right up to the ground rod and use a separate piece and run it to the water pipe? I'm worried about shovels and other objects damaging my #4 GEC's and I don't understand what is permissible with raceways. I know if you use metal (steel/iron) it will need to be bonded at both ends and I'm hoping I can use pvc to avoid that. Plus, it would reduce costs and make installation much easier.

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