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Thread: Service Entrance Grounding

  1. #11
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    Quote Originally Posted by BlaineXD View Post

    (A) Install 3 ground rods in the vicinity of the service entrance. The ground rods must be at leas 6 feet apart.
    (B) Install grounding cable as sized on the plans. Grounding cable shall be one continuous cable. It shall start on the neutral bar in the service panel, go completely through the ground bar, then through the neutral bond, and then equipment ground bond, then out through the conduit to the first ground rod, then the 2nd ground rod, and then the 3rd rod before returning back through the conduit to the service panel neutral bar.
    Looping through the rods and coming back to the panel is a very common practice here in upstate NY. You will find most grounding done that way. I am not sure how it originated, but I would guess it was a utility requirement. One of the utilities here, NYSEG, shows such an arrangement in a sketch in their spec book with the words "typical installation" or something like that which to me doesnt make it a requirement rather a suggestion. I havent been installing GEC with the loop for years and have never gotten any pushback from anyone. I cant speak for your neck of the woods.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  2. #12
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    The earthing of the grid being done in so many places is what gives the overall system a low impedance to earth.

    By adding another electrode at each service just adds to those thousands of electrodes already in place, should that one electrode become compromised it doesn't really have much impact on the overall system voltage to ground.

    Too much emphasis is put on grounding when it comes to safety concerns the most emphasis should be put on bonding.

    Even if you don't install an electrode at all on your utility supplied service - the grounding network of the entire grid still leaves you with very stable voltage to ground. Grounding electrode does help with bleeding off surges, but at same time is not a lightning protection system.

  3. #13
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    Quote Originally Posted by kwired View Post
    The earthing of the grid being done in so many places is what gives the overall system a low impedance to earth.

    By adding another electrode at each service just adds to those thousands of electrodes already in place, should that one electrode become compromised it doesn't really have much impact on the overall system voltage to ground.

    Too much emphasis is put on grounding when it comes to safety concerns the most emphasis should be put on bonding.

    Even if you don't install an electrode at all on your utility supplied service - the grounding network of the entire grid still leaves you with very stable voltage to ground. Grounding electrode does help with bleeding off surges, but at same time is not a lightning protection system.
    I just think it is worth noting that there are extensive areas that do not have a MGN distribution system thus the secondary is isolated from the primary. I know some think MGN is the way it always is and might find this odd. In upstate NY here, we have lots of 4800 delta, so the secondary neutral is isolated from the primary supply. Utility does add a GE at the pole, but sometimes that GEC has been stolen, leaving the GEC at the served structure the only earth connection. Note I am not claiming that in these cases the house GE is very important as there will still very likely be an earth reference or two on the system, such as by the well casing, etc. Even if there were absolutely no earth reference , IMO still very unlikely to be a safety issue.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  4. #14
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    Quote Originally Posted by electrofelon View Post
    I just think it is worth noting that there are extensive areas that do not have a MGN distribution system thus the secondary is isolated from the primary. I know some think MGN is the way it always is and might find this odd. In upstate NY here, we have lots of 4800 delta, so the secondary neutral is isolated from the primary supply. Utility does add a GE at the pole, but sometimes that GEC has been stolen, leaving the GEC at the served structure the only earth connection. Note I am not claiming that in these cases the house GE is very important as there will still very likely be an earth reference or two on the system, such as by the well casing, etc. Even if there were absolutely no earth reference , IMO still very unlikely to be a safety issue.
    What does that GE at the pole tie to? If a shield wire that runs all throughout the system, you still have a pretty large grounding network, and even better then a MGN because it isn't normally current carrying so no voltage drop issues to cause rise in voltage on the grounded conductor.

    Distribution around here is all MGN, transmission lines don't ordinarily have a neutral but still have shield wire that is tied to an electrode at nearly every structure.

  5. #15
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    Quote Originally Posted by kwired View Post
    What does that GE at the pole tie to? If a shield wire that runs all throughout the system, you still have a pretty large grounding network, and even better then a MGN because it isn't normally current carrying so no voltage drop issues to cause rise in voltage on the grounded conductor.

    Distribution around here is all MGN, transmission lines don't ordinarily have a neutral but still have shield wire that is tied to an electrode at nearly every structure.
    I am not sure what the configuration of the larger distrubution and transmission lines are, but they typically have a shield wire. Typical rural distibution however is just two wires, two delta phases, no shield wire. Secondary neutral and arrestors just tie to rod at base of pole, thats it.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  6. #16
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    Quote Originally Posted by electrofelon View Post
    I am not sure what the configuration of the larger distrubution and transmission lines are, but they typically have a shield wire. Typical rural distibution however is just two wires, two delta phases, no shield wire. Secondary neutral and arrestors just tie to rod at base of pole, thats it.
    You probably can't answer but is also likely that distribution system is not grounded? They may have some sort of ground fault detection system to warn them of troubles, but at same time only one fault in the system - the system would remain in operation as long as there isn't a second fault on another line.

  7. #17
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    Quote Originally Posted by kwired View Post
    You probably can't answer but is also likely that distribution system is not grounded? They may have some sort of ground fault detection system to warn them of troubles, but at same time only one fault in the system - the system would remain in operation as long as there isn't a second fault on another line.
    I think historically this system was 4800 delta (ungrounded), although most road have only two of the phases. I know some of these lines are now fed off newer wye systems. When that is the case, I am not certain if they are isolated or not. For example if a 4800 line was fed off a grounded wye system via autos, it would of course retain the earth reference from the wye system. That is just conjecture, I am not sure if they do that or not. I know of one case where they use an isolation transformer off a 7.2/13.62 wye to feed an old 4800 line. The same thing happens with my road, fed off a 7.62/13.2 wye and I know where that bank is but I havent looked close enough to try to figure out if its an auto or an isolation.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  8. #18
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    Quote Originally Posted by ActionDave View Post
    It looks like a silly requirement to me. For instance, how does it make one bit of difference if the wire to the ground rods is one continuous piece instead of one jumper from the first ground rod to the second. It doesn't, it's a stupid piece of copper tying one ground rod to the next, the ground rods have no idea if the wire is spliced or not either, they are stupid too. There is also no reason to bring the grounding electrode conductor back to the neutral buss, there is no reason not to either other than it's a wast of material and effort.


    Any connection to the earth has no purpose in creating any path of least resistance or clearing a fault, that is what good equipment grounding practices are for.


    Unless you are working on a telecom or similar site, or maybe a fancy server room or similar then earthing connections are not a big deal.
    >>>>>>>

    It looks like a silly requirement to me.
    Maybe to you but not the Licensed EE that wrote the spec. The EE wants it done that way.



    For instance, how does it make one bit of difference if the wire to the ground rods is one continuous piece instead of one jumper from the first ground rod to the second.
    The EE wants the GEC continuous unbroken. Maybe he has a thing with unnecessary added connections in the EGC. Maybe his thinking is long term well past the time of the date of the installation. Maybe he is looking out 5, 10, 20, or ?? years down the road. The top of the ground rods and ground rod ground clamps will be buried below earth 4" to 6". Maybe the EE worries about corrosion at unnecessary connections. If the GEC is continuous it's not a problem. In the end it really doesn't matter. That's the way the EE wants it done.

    As for why the EE wants a continuous closed loop GEC maybe it is for simple redundancy. Agan, that what the EE wants.

  9. #19
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    Quote Originally Posted by Jamesco View Post
    As for why the EE wants a continuous closed loop GEC maybe it is for simple redundancy. Agan, that what the EE wants.
    Maybe it is because the EE does not understand grounding and is simply repeating what 'granddad did'. Just because an EE asks for it does not make it automatically a good or bad design.
    Just because you can, doesn't mean you should.

  10. #20
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    Quote Originally Posted by Jamesco View Post
    As for why the EE wants a continuous closed loop GEC maybe it is for simple redundancy. Agan, that what the EE wants.
    When it comes to The Ground there a lot of people who come up with a lot of things that don't make sense.
    If you go and decide to dance with a gorilla the dance ain't over till the gorilla decides it's over.

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