According to Wikipedia, CMEs have a top speed of 3200km/s. The earth is 147Mm from the sun (at its closest), so we'd have a minimum of 12 hours warning. How v

According to Wikipedia, CMEs have a top speed of 3200km/s. The earth is 147Mm from the sun (at its closest), so we'd have a minimum of 12 hours warning. How vulnerable are electronic devices that are powered off to CMEs? I imagine that while we have sufficient warning, there is also considerable variation in CME speed (and size?). It might be difficult to coordinate "turn stuff back on" day without functioning communication systems.