Peter, K9STH has some excellent information on tower grounding on his web site. He has worked at this professionally. _http://home.comcast.net/~k9sth/Lightning_Primer_1.htm_ (http://home.comcast.net/~k9sth/Lightning_Primer_1.htm) _http://home.comcast.net/~k9sth/_ (http://home.comcast.net/~k9sth/) 73, Terry, K7FE