Buried Earthing Grid in Concrete Foundations - German Philosophy

[Jpascp]

Attached file with some photos of buried earthing grid inside concrete foundations.

 

[waross]

German Philosophy​

US origin and North American Codes.
Google "Ufer Ground".

Wiki: Ufer Ground;
During World War II, the U.S. Army required a grounding system for bomb storage vaults near Tucson and Flagstaff, Arizona. Conventional grounding systems did not work well in this location since the desert terrain had no water table and very little rainfall. The extremely dry soil conditions would have required hundreds of feet of rods to be driven into the earth to create a low impedance ground to protect the buildings from lightning strikes.

In 1942, Herbert G. Ufer was a consultant working for the U.S. Army. Ufer was given the task of finding a lower cost and more practical alternative to traditional copper rod grounds for these dry locations. Ufer discovered that concrete had better conductivity than most types of soil. Ufer then developed a grounding scheme based on encasing the grounding conductors in concrete. This method proved to be very effective, and was implemented throughout the Arizona test site.

Basically 20 feet of bare copper cable cast in the concrete.
Using the re-bar will be a matter for local codes.
Using the re-bar is not always a good idea.
A heavy fault current may over-heat a small re-bar to the point that the concrete is fractured.

 

[Jpascp]

US origin and North American Codes.
Google "Ufer Ground".

Basically 20 feet of bare copper cable cast in the concrete.
Using the re-bar will be a matter for local codes.
Using the re-bar is not always a good idea.
A heavy fault current may over-heat a small re-bar to the point that the concrete is fractured.

We do not use any copper inside as foundation reinforcement electrode. Normally is used galvanized steel plate since is cheaper as shown in photos. Nowadays in industrial projects is normally also to connect buried main earthing grid to reinforcement foundations. In this way the total impedance will decrease.

Yes some studies indicate that some heavy fault currents cna craks the concrete. I have never seen it as a REAL case.

 

[IRstuff]

If you give lightning a good path, it will take it. There are lots of examples of sand turned into glass from lightning strikes; I would think that such a path would not be good for concrete.

 

[7anoter4]

It could be interesting.

 

[7anoter4]

See also BS 7430:2011
9.5.8.5 Structural steelwork