Letter: Faraday Cage Question

Faraday Cage

Good afternoon!

I have a question on adapting a homemade Faraday cage. I am getting a little paranoid about these two North Korean satellites in orbit over our country.

Would a metal mailbox, such as can find at the local hardware store, be acceptable protection? I am trying to put together something simple for really, really cheap! It has a larger size and is easier to obtain. It is also cheaper than some of the other options I have been reading about on constructing a Faraday cage.  T.B.

HJL’s Comment:

Most any metal container will work as a Faraday cage with a few simple preparations. The metal needs to have a good electrical connection between the various parts. If you are using painted metal, you will have to remove the paint where the electrical connection needs to exist. Galvanized metal works really well. If a metal mail box is not large enough, you can consider a 30 gal trash can with a metal lid…. Continue reading

Letter: Advice for Disabled Suburban Retiree Preppers

HJL and JWR,
I’m seeking links or tips on how a 77-year-old disabled person can defend his property in case there’s TEOTWAWKI. My wife is 72.

We live in a middle class subdivision 45 miles from Cleveland, Ohio. Because of physical disabilities (neuropathy, bad knees and legs) I am not very mobile.
I use walker/cane most of the time.

We are moderately prepared (food, guns, ammo, junk silver, etc. A retired Marine lives at the other end of the block but says he will bug out if SHTF.
Nobody else on the block seems even to be aware of the dangers of a potential disaster (natural or man-made).We are one block from main artery, one mile from an interstate.

Finally, where is the best place to shop for potassium iodide?

Thank you for what you do on the blog.  We have been … Continue reading

Letter: Using Military Ammo Cans for Faraday Shielding

Dear JWR:
The use of military surplus ammo boxes as Faraday shields was recently mentioned again in SurvivalBlog.  But readers should be reminded that these cans will not work in the configuration where they are normally purchased.  This is because the boxes have a rubber gasket to seal the lid from water and that makes the lid not in [electrical] contact with the body of the can, thereby losing the [EMP] shield effect.  Regards, – Dave X.

JWR Replies:  You are correct.  As mentioned previously in SurvivalBlog, the best approach is to remove the rubber gasket,  rough up the metal on both the top edge of the can lip and in the gasket groove (with sandpaper, a wire brush wheel, or a Dremel tool rotary stone) and replace the thickness of the gasket with stainless steel wool which is tacked in place with small globs of epoxy … Continue reading

Letter Re: EMP Telltale


Whenever the power goes out wherever I am, the first thing I do is see if my battery-operated watch is still working. I suspect one of these times, the screen will be blank or just chaos. – Sid, too near Niagara Falls

HJL Comments: As technology advances, the gate sizes grow smaller making such electronics more susceptible, but at the same time manufacturers recognize that they are more susceptible to static electricity as well. As a result, manufacturers almost always include some basic protection in the on-board circuits. Add to that the concept that the amount of energy absorbed by these electronics is directly related to the amount of “antenna” on the circuit board and you end up with practically no idea whether your watch will survive or not. The circuits are so small that the antenna lengths are negligible (unless you happen to be plugged in charging the … Continue reading

Using EMP-Hardened HF Ham Radio to Send/Receive E-Mail During Nationwide Outage- Part 1, by PrepperDoc

There are multiple possible scenarios that may result in a regional an/or national combined loss of Internet connectivity and cell/telephone service, during which you would probably wish to maintain communications to loved ones and others. EMP may destroy routers, cell towers, and power sources; solar coronal mass ejection (CME) may remove power from all communications systems; cyber warfare may have similar outcomes. Travel in some of these circumstances will be difficult, or dangerous to impossible.

Ham radio VHF/UHF repeaters may go down, due to power outages or EMP. Direct, point to point simplex VHF Ham radio will still work (even after an EMP, if hand-held radios were at all hardened or protected) over modest distances. Long range HF direct Ham radio communications will work (possibly after a delay of any EMP), presuming you had protection (if EMP) and have your own power. However, they will be of less usefulness … Continue reading

Letter Re: Shielding Electronics From EMP

Another point on electromagnetic pulse (EMP) and Faraday cages is even something simple can be protective. There are 30 Gallon galvanized steel trash cans with lids (made in the USA!) available at my local farm and ranch store for $22. This makes for affordable and easy storage, and you can wrap things in common aluminum foil. Or even something like a steel cabinet or vault, but generally try to avoid gaps or spaces. It doesn’t have to be zero signal, but reduce the field strength enough to prevent damage.

Vehicles have some protection for many years. In the early days of electronic ignition systems, truckers with CB linear amplifiers were causing police vehicles to stall. And driving near powerful radio towers also caused some glitches. The protection added since the early 1970s isn’t military grade, but realize if your vehicle doesn’t even hiccup when it is next … Continue reading

Two Letters Re: EMP Effect and Pacemakers

While case-by-case circumstances can effect the practicality of many alternatives, there are external pacing and monitoring options. The Zoll Company for example has just released a type of vest, worn similar to a brassiere with a fanny pack (battery pack). This device consistently performs cardiac monitoring and when a shockable rhythm presents itself the device does just that. More archaic methods would involve adhesive defibrillation or subcutaneous pacing patches and a cardiac monitor, while the monitors can be significantly expensive, older models are available at online auction sites. Both the aforementioned devices can be recharged, and more importantly, stored in a Faraday cage to protect them from an EMP. Neither would be as convenient as implanted devices but in a pinch could be just the thing to keep that ticker going.  – John, EMT-P.

Dear Editor:
You aren’t safe even when it is not an … Continue reading

Letter: EMP Effect and Pacemakers

I have an implanted cardiac device (a pacemaker and defibrillator) and, after reading the letter about possible effects of electromagnetic pulse (EMP) on batteries, became curious as to how an EMP or maybe a strong solar flare could affect my device. I searched SurvivalBlog’s archives and saw that such an event could possibly damage the implanted cardiadefibrillator (ICD). Is there any firm evidence as to what may actually happen to an ICD or similar device in the human body and anything that can be done to counter the effects? It seems it will be a bleak future for the millions of people whose life depends on some form of technology in the event of a worse-case scenario, but, God willing, I still plan on having a long life. Thanks. – J. “Doc” Holiday

Hugh Replies: Yes, this is a troubling issue. Integral pacemakers with defibrillators have leads … Continue reading

Letter Re: EMP Question


I’ve asked Matt Bracken this question, and he didn’t know. I’ve read all of your EMP-related data, but none of them answer the question of whether batteries, particularly the small D, C, AAA, AA types need to be shielded to protect them from EMP. All authors make much of electronics in devices but never mention separate stores of batteries or the dangers of batteries stored in electronic devices like radios, sights, et cetera. Your advice would be greatly appreciated. – S.D.

Hugh Responds: There is much FUD in the online world (and in books) about EMP. Some of it is well deserved, and some of it is simply because of ignorance about how such forces work. There are two interrelated factors that are critical in determining how destructive an EMP would be towards electronics:

  • Peak impulse energy
  • Length of the reception antenna
  • The peak impulse … Continue reading

    Two Letters Re: The OTHER Electrical Grid Failure Problem


    I just retired from 24 years of bouncing around the nuclear plants in the U.S. and abroad. For work planning, fire stop penetrations, and OSHA worker safety, every nuclear plant in the world has at least 20 electricians on-site 7/24. During a refueling outage, add 100 to that number. – K.G.

    o o o

    Hello Hugh,

    I read the comments about electricians at nuclear plants and the inability to have more than one or two there in an emergency situation. While I am not disputing that possibility, the entire situation should be told. Electricians are support staff at any nuclear station. I have been an electrician at a dual unit nuclear station for over eight years after years of being a contractor. We work for the Operations Department, which is there 24/7/365, and they are required per NRC Tech Specs to maintain minimum staffing at all times. So there … Continue reading

    Letter Re: The OTHER Electrical Grid Failure Problem


    Four hundred forty nuclear reactors are operating worldwide, representing about 14 percent of global electricity generation. Sixty power plants are under construction, and many older plants slated to be decommissioned may be given new operating licenses. Which country has the greatest number of nuclear reactors (want to guess)? We do; in the U.S. there are approximately 100 plants currently operating. Now imagine a map of the United States, taking a ruler and drawing a straight line from the northern border with Canada, which would head south through the edge of Minnesota, continue through the very edge of western Iowa. the very eastern portion of Kansas, eastern third of Oklahoma, with the southern portion of the line entering the Gulf just west of Houston. We now have a east and west designated portion of the U.S. The western designated portion contains approximately 15 operating reactor sites with one or more … Continue reading

    Surviving EMP: Suburban Circle Garden- Part 2, by Northwest Native Elder

    Step 3: Buy the best of plants for surviving

    I have listed the vegetables below that I have planted and that have proven successful for me. Also, I have ordered the following plants from 1-5 with #1 needing the most sun and #5 needing the least sun. They will all benefit from the most sunlight they can get, but tomatoes need full sun and heat. It is a short list but an important one. These are the plants that you, as an inexperienced gardener, will have the best chance at growing, storing, and surviving on. You may have to supplement your diet with animal protein of some kind, but remember “any food is better than no food”. When it is time to buy seeds, you may want to think about buying enough for your neighbors who surround you. This is inexpensive insurance to protect your own garden. If they plant … Continue reading

    Surviving EMP: Suburban Circle Garden- Part 1, by Northwest Native Elder

    Being descendants of Native Americans and Swiss/German immigrants, my family has survived and thrived off our land for generations. We hunt and gather an abundance of local food– venison, salmon, elk, smelt , crab, clams, acorns, huckleberries, and seaweed– from the Redwood Forests, Wild Rivers, and Mighty Pacific Ocean, and we cultivate our “civilized” gardens and orchards, grown in the manner brought by our European ancestors. Having the best of both worlds so to speak, we have never really experienced a lack of food in our area. The art of gathering, growing, and preserving food for winter has always been the top priority for us. Preparing for disasters has also been a full-time job around our home, and believe me where I live in the Pacific Northwest there are plenty of disasters, such as earthquakes, tsunamis, floods, wildfires, drought, economic collapse, foreign invasion, and/or EMP to prepare for. While all … Continue reading

    Letter Re: Thoughts for Frozen Food Storage for SHTF


    I sure would like to hear what Prepperdoc has to say about the conclusions of G.D. on the resilience of the simple freezer in the event of an EMP. It would be nice to know brand name. I have looked at Sundanzer products (24vdc) but was not encouraged by reviews and troubled by the exposure to EMP. It is preferable not to wander in the wilderness. – R.V.

    Prepperdoc Responds: Great question, made me do even more study. My personal plan has included household freezers just as contributor G.D. is using. Are these susceptible to EMP / solar flares (e.g., Carrington event)?

    Apologies in advance, this is somewhat tedious stuff.

    Your biggest concerns are to protect against both the E1-type and E3-type components. Let’s take them separately.

    The E1 component of an EMP contains huge amounts of radio frequency power from very low frequency radio waves on … Continue reading

    EMP Protection For Electronic Safe Locks, by PrepperDoc

    Like many preppers, I have a safe with a digital lock that I purchased before I understood EMP, and I would now like to have some protection for that lock against the E1 component of an EMP attack. (Because the lock is not attached to any very long wires, the E3 component is not an issue.) I present here a simple technique that may provide significant (although imperfect) protection and which is amenable to becoming a commercial product by a motivated individual (and I freely give away the idea). Such additional protection would be expected to raise the probability that I won’t have to hack into my own safe after an EMP event.

    The accompanying photo shows a swath of household aluminum foil simply pressed over my digital lock and held in place with a rubber band. The outer portions are hand-pressed to lay … Continue reading