LogFAQs > #979812132

Pro tip.
A small nuclear warhead detonating over a large area at around 300miles above the surface area can create a wide-ranged EMP. This will cause most electronics to freak out, but then settle back into their everyday behaviors. However, the power grid needs to be within less than 1% of its frequency of 60hz before the systems automatic shuttof occurs. This can cause a cascading brownout that eventually shuts off the power grid itself until different region within seconds as the carefully monitored loaded systems are completely thrown out of balance. This will require a trained professional to drive out to each location and fix the system, one breaker at a time, at every junction box. If any of the frequencies are misaligned by 1% when the new two power systems entwine, it can cause the cascading brown out all over again.

This is all public information too, it's just a matter of looking it up.