Are electromagnetic fields created by lightning the same as an EMP created by a nuclear weapon?

[ericsarratt]

Two questions:

1) I was listening to Mike Holt's video: Grounding, System and Equipment [250.4, 2020 NEC].

At 23: 21 he notes that lightening creates an electromagnetic field which puts pressure on electrons inside the metal parts of the building. Those electrons are trying to get to the earth, to ground.

Question: Are electromagnetic pulses (EMP) of a nuclear weapon same thing as a lightening's electromagnetic field, but on a larger scale?

2) Are the electrons in water affected like the electrons in metal during a lightening strike OR is water in a house's plumbing tub/shower just conducting the energy of the lightening?

 

[roger]

I don't know but I had an insurance policy on a 1977 GMC pickup that had specific wording that it would not pay for paint damage due to nuclear fall out.

I think damage from a lightning stroke would be covered.

 

[__dan]

There would be generally two effects and then the materials would behave differently depending on if they are conductors or insulators.

You would have a strong electric field and travelling current, so EM, electromagnetic radiation. But then you would also have ionizing radiation, not the same thing, but there could be some overlap.

In materials that are conductors, the travelling EM pulse induces current and Voltage in the material. Then the problem if if the Voltage and current exceeds the rating or withstand, where damage occurs. So for lightning, the high Voltage induced pulse travels the wires, even for non direct nearby strikes, but the distribution system may carry the excess Voltage quite some distance without itself being damaged. Carried up to the point it hits something fragile like a semiconductor device or circuit, or off the wire onto the board foil, and that blows. Could be over the wires and through the air, both.

For non ionizing EM in non conductive materials, water, the effect would be benign, inert. The lightning strike would be mostly non ionizing EM as long as you were not directly in the path of the lightning itself.

Ionizing radiation from a nuke strike would tear molecules apart and create conductive ions from non conductive base materials. The you would also get the effect of the coincident EM causing conduction effects in the ions. The energy required is many orders of magnitude more.

I believe they could be said to be similar and differ only in orders of magnitude quantity difference and whether the radiation is EM only, or if it is also ionizing radiation.

 

[drcampbell]

The neutron burst from a nuclear weapon (or the neutron flux inside a nuclear reactor) will transmogrify elements.

For example: If a carbon atom captures one neutron and emits a beta particle, it will become a nitrogen atom. If a lot of carbon atoms in your insulation become some other kind of atom, the polymer chains will fall apart and it will degrade its performance as an insulator.

 

[junkhound]

EMP frequencies from high altitude (50,000 ft) are up to the hundreds of MHz, EMP from a ground burst levels are 100X typical lightning,, plus the gamma and acoustic blast, so any NEC grounding scheme is meaningless for ground nuke.

Lightning typical has a 6 us rise time so frequency content is well below EMP.

What that means is that most surge protection in a service panel will not do squat for even a high altitude EMP as the inductance of leads is more than a few NANO heneries.