Not too sure about that pesa, as long as there is copper going...

Not too sure about that pesa, as long as there is copper going back to the exchange you increase the risk dramatically of having equipment damaged by an EMP pulse, if all that is entering the exchange is fibre, then shielding can possibly cope with any pulse, we aren't talking of a few volts here, we are talking about thousands of volts induced into the copper, which takes it back to where the electronics are situated, it (the copper) is basically one big lightning rod, so it isn't that simple.