It doesn't have to be an EMP.

The American electric grid is highly vulnerable to hacking - many of the pertinent controls are connected to a network, and if you're connected to the network, the network is connected to you. There is a member of my family working in security. This individual is one of the hackers that work to prevent hacking, and I have it on good authority that if some group of people could hack into the controls of the various grid systems across the continent and overload the grid (make it so that so much electricity is passing through the grid that it effectively shorts), it could be fried in that way.

It wouldn't be as bad as an EMP event because it would only effect access to electricity through the grid and damage only electronics directly connected to it, but it would be very bad nonetheless.