Ufer was the name of the radio(?) engineer who first came up with this solution around WWII. Tall radio towers built on high mountain points with rocky soild conditions seem to benefit rom this method as far as LIGHTNING protection concerned.
To utilize the same method for electrical grounding raises several problems.
In grounding systems there are always current flows present that are equalizing current flows between different potential due to several different reasons. This unpredictable current flow and the varying moisture content of the concrete, combined with the alkaline characteristics of the concrete will rpoduce galvanic interaction between the copper wire and steel rebar, eg. corrosion, in the structural rebars AND the grounding system itself. The performance and deterioration is unpredictable. The deterioration of the structural integrity can not be remedied.
Due to concern about corrosion civil engineers sometimes specify epoxy coated rebars. In that case the rebars would be ineffective as a grounding media.
The NEC suggest that when rebars are utilized as grounding that they should be "bonded together by the usual steel tie wires or other effective means". Again corrosion will have deterious effect on thse connections and bonding it together by other means is probably not a cost effective method.
Lighting strikes had already demonstrated their destructive effect by striking the reinforcment and had blown concrete apart as predicted by another comment. That happened without intentionally trying to direct the lightning strike through the rebar.
Unfortunately the NEC is in great error in not addressing cathodic interaction of dissimilar metals in grounding system and discloses it's fundamental defficiency in establishing rules without sound engineering and scientific background and backup. But that is a whole other discussion.....
In short, fawgedeboutit....... Laszlo Weress Reply to this comment |