Thank you for your question regarding UFER earthing, it is our pleasure to help.
The term “Ufer Ground” is synonymous for other terms such as “Building Steel” of “Concrete Encased Electrode”. The National Electrical Code (NEC) Artcile 250.52(A)(2) specifically requires that the rebar in your concrete slab be bonded to your earthing system. Please refer to the NEC Handbook, Exhibit 250.22, 250.23, 250.29, and 250.31 for visual examples of this mandatory bonding. This is a very old portion of the code and has been enforce for many decades now, possibly for half a century. Every building built in America (and the rest of the industrialized world) must be bonded to “Ufer Ground/building steel/concrete encased electrode/rebar” in addition to any other earthing systems, as a matter of safety.
The following excerpt about the Ufer Ground System is from Wikipedia:
During World War II, the U.S. Army required an earthing system for bomb storage vaults near Tucson and Flagstaff, Arizona. Conventional earthing 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 copper rods to be inserted into the earth in order to create a low enough impedance earth 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 earths for these dry locations. Ufer discovered that concrete had better conductivity than most types of soil. Ufer then developed a earthing scheme based around encasing the earthing conductors in concrete. This method proved to be very effective, and was implemented throughout the Arizona test site. After the war, Ufer continued to test his earthing method, and his results were published in a paper presented at the IEEE Western Appliance Technical Conference in 1963. The use of concrete enclosed earthing conductors was added to the U.S. National Electrical Code (NEC) in 1968. It was not required to be used if a water pipe or other earthing electrode was present. In 1978, the NEC required rebar to be used as a earthing electrode if present. The NEC refers to this type of earth as a “Concrete Encased Electrode” (CEE) instead of using the name Ufer earth. Over the years, the term “Ufer Ground” has become synonymous with the use of any type of concrete enclosed earthing conductor, whether it conforms to Ufer’s original earthing scheme or not. – Wikipedia
If you should have any further questions, please do not hesitate to contact us directly at 310-318-7151. They will be glad to speak with you about your project, free of charge.
The Engineering Team at E&S Earthing Solutions
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