Other than a few brief words I have read, I know nothing about this, but am looking forward to posts so I can learn.....!
mechanic, defense assessments indicate that only 2-3 nuclear devices detonated just above the atmosphere over North America would do the trick. No radiation, no fallout, no flash of light, no blast, no heat ... At most we'll feel a tingle from hundreds of amps per square yard travelling at the speed of light, and most of it will hit the ground and dissipate. However every piece of metal or wire, and the longer the more energy it absorbs, will conduct it right into circuits. Even military grade breakers and surge protectors won't work as its front loaded, so it dumps the energy faster than the circuit can trip.
Let your imagination run wild with that for a bit and you get the picture; just pray you're not on an airplane at that time. If you're on the ground, it'll be like a power outage, but you'll try to call the Electric Company and the phones won't work. You'll go outside and all your neighbors will be wondering what happened, and all the cars will stop moving. Your neighbor with the generator he bought for Y2K will try to start it and it won't go. With a name like mechanic, you'll probably be doing good about then as you might have a car with no solid state electronics in it.
So no more power, water, sewer, phone, radio, tv, cars, planes, trains, boats, backup generators, hospital equipment, pacemakers, insulin pumps ... that's probably alot of the important items. Probably alot more I'm missing.