Decision of combined and transforming lines shielding under lightning strokes

Modern lines of communications can include lines of different types: symmetrical, coaxial, fibre etc, even they have a short length. Moreover, in modern communication lines IP- telephony and packet switching are widely applied. Different parts of the same document can be passed on different lines in different moments of time. Thus, probability of lightning damage of such compound and virtual channels is not constant during the different moments of time. Some aspects of this problem are touched in this article