Electro Magnetic Generator Damage - Discussion

[Tom Reed]

NASA had an announcement about it again, just last week. http://www.dailymail.co.uk/sciencetech/article-1313858/Solar-flare-paralyse-Earth-2013.html

From what I've read putting electronic items in a microwave or a galvanized trash can will protect most items.

[Horsepoor]

Like most of us, I from time to time think about the threat presented by the Hitler of Iran or the little pot belly pig up in North Korea. Iran has multi stage rockets with sufficient lift capability to get a payload into low earth orbit (i.e. 80 to 120 miles). Heck, even a SCUD as used by Iraq in the gulf war reaches an altitude of at least 60 miles before descending back to earth and this is late 1950s early 1960s technology.

Assuming Iran has launch capabilities to place a payload at least 120 miles up, which might not sound that dangerous until you consider an old oil tanker or freighter configured to launch a rocket out of a hold. It would not be hard to run one or two ships up to the east or west coast of the US launching a low yield nuclear warhead into space over the USA. Note: An effective EMP can be generated by relatively low yield nuclear bomb in the megaton or less class. I'll bet Iran's Hitler has several bombs by now given the pussy approach our government has taken. OK, back to the EMP threat.

I cannot afford to build a metal Faraday cage or Faraday shield and I suspect this cost is beyond most of the forums' members, but I have a thought. I have a few acres, as do most members. What would happen if the next time I have a Bobcat over here moving some dirt around, I just dig a hole with a ramp. It would be easy to dig a 6 X 8 X 4 foot pit, pour some 4 in thick sides, a floor, roof, etc, then cover the pit with a couple of feet of dirt. The pit would be flush with ground level. I've poured a small concrete roof (4 x 8 foot) over my old generator shed by building a form out of a sheet of plywood, using 2 x 4s to support the flat surface as I poured concrete onto the top of the plywood sheet and onto the rebar for roof thickness of about 4 in. This was a small free standing concrete roof. If I were to fabricate a 6 x 8  foot slab that I intended to crawl under from time to time, I would leave some type of metal support in the middle of the roof to ensure the center has support.  

Anyway, in this pit, one could store spare water pumps, ST heads, electronic modules for most of my vehicles, and all the other electronic stuff, which would be very useful after an EMP. For a couple a cubic yards of concrete and some scrap lumber to make forms, I might have $200 or $300 in materials. I wonder if a shallow underground pit would shield the contents form an EMP attack? Your thoughts? Does anyone know the effects of earth on EMP wave propagation?    

[Randybee1]

Bruce, my understanding of the EMP stuff is.. and I'm no EE.. is that a Faraday cage is very simple and easy to build. Just make a box out of metal, any metal. Ground that box with a grounding rod. When an EMP pulse hits the metal roof, wall etc it will quickly be redirected to your grounding rod averting damage to whatever is inside your box. Instead of digging and pouring concrete I think an easier ( and maybe cheaper?) method would be to buy one of those small tin sheds, or build one yourself and ground it. The floor inside could be concrete, just don't let it touch your metal walls. I built 2 such structures myself. I just ordered the metal from a local roofing company.. I park my cars in them and that's where my generators are. I did not build these originally as Faraday cages, I just didn't want to wrap the frame in wood. I built these as a garage port and a shed. I have not grounded these yet but I will this summer.

I think the concrete would only slightly attenuate the EMP signal.. how much I do not know.

Randy B

[mike90045]

In the thick, soupy part of the atmosphere (10,000 feet and below) EMP becomes very limited, the pulse is squelched before it can build up much.  it's the 5 miles high, and higher (up to 300 miles)  that generate the hemisphere killer pulses.  Of course, the optimum hight is not published.

But, back to your dugout bunker, if you add a couple of layers of galvi metal mesh in the concrete or dirt, I think just a few feet of damp dirt really tones down a pulse, because it's a lossy conductor.   Store gear in a metal trash can with a tight lit, and you've done good without spending a fortune.    Or use a chunk of steel 12' di culvert pipe dug into the hill as deep as you want.

Wikipedia has a pretty good article   http://en.wikipedia.org/wiki/Electromagnetic_pulse
and some charts showing the effect the earths magnetic field has on the pulse footprint.

[Horsepoor]

I found the link an interesting read. I plan to absorb and read it over a few more times. Thank you, very intersting.

[veggie]

I think concrete and earth would provide little protection against a substantial EMP wave.
Adding steel mesh would only help if the mesh size was smaller than the wave length of the pulse.

The pulse which NASA is warning about has the potential to be much more destructive than a single nuclear EMP blast.
NASA states that it's not a question of "if" it happens in 2013, but how strong the pulse(s) may be.
Looking at the two extremes, it could amount to nothing or it could cause major disruption to power grids and magnetic media.
I'm not a tin foil hat wearer, but I think it would be prudent to prepare for this one.

veggie