All these worthy analysts assume that the risk has to be an internal risk. That is not the case with distributed equipment. Faulty bonding and grounding in the building can cause enormous potential differences in building steel and ground paths, in case of lightning strikes. Whether you are talking about a PABX or a LAN, as soon as you start stringing things together throughout a building, you can no longer look only at the risks of something happening in the equipment, you have to look at the risks of something happening in the system. The designer of the equipment may well have been absolutely ignorant of what uses the purchaser puts the equipment too. The installer of the equipment may be without any clue as too how well the building steel is bonded, etc., etc. Therefore, although there is no way that anyone can or should guarantee absolute safety, the designer of the terminal must assume worst case and very rare scenarios.
Ciao, Vic
