Hi all, let me bring a different perspective. In the aircraft world we have a lightning tests that stress interface wiring travelling some distance WRT local wiring.
The reason we do this is because when lighting strikes the plane, the fuselarge(?) carries MANY amps, and there is a voltage drop between any two points. If a piece of equipment is connected to a another some distance away, the interface lines can see many hundreds, even thousands of volts.... Even the capacitive coupling between the equipment case and the surroundings is enough to see this effect. If this situation is on the ground, and lightnig strikes a part of the building that causes PE current to flow in the buiding ground. The wires connecting to other equipment will ride the shift in ground potential. the greater the distance, the larger the shift. It does not have to be in a seperate building..... Since only data/com lines travel some distances, thay are most likely to encounter this threat. I suspect that this is where the requirement comes from. Now as for what levels to apply.... Have a great weekend, Derek Walton ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson: pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org