Terry, that I will admit with some pain was a bad show. Not bad as in I watched it and then after it was over noted it was bad, but bad as in watching it for 10 minutes then turning it off bad. I've pretty much totally given up on hollywood type broadcasting companies, to do a show like that requires at least some effort to be critical of the actual causes of collapse/failure, and commercial mainstream tv just is not going to do that in general.
However, I believe you got the premise slightly wrong, not sure, and I certainly won't go back to watch it to confirm or deny it, it's on hulu.com if anyone wants to see, but I believe the event that broke all the electrical systems was largely unknown as to cause, as you note, not an EM pulse, but something. Now I could have gotten it wrong, or they could have gotten more specific later in the show, but there's no way I would watch more of it.
There's a better show called Jeremiah on hulu.com about post disaster life, it's reasonably believable, and doesn't violate its premises too badly, although it's certainly not a great show by any means, but it is somewhat consistent, bad people continue to be bad, power continues to corrupt, and efforts to do things right don't always have great outcomes. And they get the machines running again.
But this show is bad, typically bad hollywood lack of imagination and risk taking bad. Unwatchably bad. Better to go out for a night hike in the rain, bad.