Purpose of ground rod

[hornetd]

No ground rod (loop back) is less than 25ohm?

Would you be so kind as to expand on this some? What do you mean by "(loop back)?"

Tom Horne

 

[FionaZuppa]

The loop formed between GEC to earth back to some other reference point.

 

[hornetd]

The loop formed between GEC to earth back to some other reference point.

With the clamp on ground loop impedance testers the other reference point is all of the other Grounding Electrodes in that entire substation's served area. Now I get it.

Tom Horne

 

[kwired]

With the clamp on ground loop impedance testers the other reference point is all of the other Grounding Electrodes in that entire substation's served area. Now I get it.

Tom Horne

and likely beyond that, isn't the shield wire on incoming substation line(s) also bonded to it?

 

[hornetd]

and likely beyond that, isn't the shield wire on incoming substation line(s) also bonded to it?

Never having done an an Outside Wireman's work, except as a laborer on a Power Production crew and that hardly counts, I know nothing about the systems beyond the sub stations. I wouldn't know that shield from Adam's off aunt.

 

[kwired]

Never having done an an Outside Wireman's work, except as a laborer on a Power Production crew and that hardly counts, I know nothing about the systems beyond the sub stations. I wouldn't know that shield from Adam's off aunt.

That shield is bonded to the grounded conductors of the secondary therefore extending the grounding system to even more electrodes connected to the shield, possibly at every transmission pole in many cases and at very least the grounding system at other substations since they are bonded to it as well. In effect the grounding grid at any one point of the sub system is not just in an area served by a particular substation but rather everything in the entire wide area grid that has interconnection of grounded components. So in much of the US there are rather large areas that are interconnected and your grounding grid essentially covers all of whichever area you are located in at very least. Should there be a connection between any those major regions, then that might make the grounding grid effectively even larger, though that probably is insignificant to most individual services and even to localized substations.