Grid

[MineGuy]

Hi,
I was reading a calculation done by one of the guys in our office and it reads like this: The ground rods consists of of the steel reinforcing bars in concrete piles.
I studied the whole calculation. But it was strange to find that rods were randomly spaced. But as per code, the two rods cannot be spaced less than the length of the rod and not more than twice the length of rod.Could you advise, is it at the discretion of the designer.What does the above steel bars mean, normally we used copper bars.
Thanks

 

[dpc]

Google: "Ufer ground"

 

[RRaghunath]

Steel reinforcement bars in the concrete are not supposed to be counted while sizing the grounding grid. IEEE 80 explains this further at length.
This is not to say that the reinforcement bars should not be connected to the ground grid, as the safety code requires that all the metal near to the ground grid needs to be bonded to the ground grid.
Trust the above is helpful.

 

[cuky2000]

Larger rod space separation is more effective than reduce separation. For example, the resistance equivalent of 5 rods with respect to single rod for space L=1/2, 1, 2 and 4 time their length is approximatelly as follow:
* Straight configuration: 32%, 24%, 17% & 12% respectively.
* Ring configuration : 25%, 22%, 16% & 10% respectively.

For additional information, see the enclose figures