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Letter Re: EMP Protection Measures

Hugh and James:

I’m missing something regarding EMP protection measures, and I could use some help.

I have researched EMP, how it’s created, and the common frequencies of EMP. I’ve looked into its relative intensity based on creation mode, altitude (in the case of nuclear devices), and the extended effects attributed to conductive networks. I understand what a Faraday cage is and how it works. And I’ve read numerous articles, lots of forum comments, endless opinions, a quantity of engineering documents, and several much learned evaluations on protecting against EMP.

The Problem

So here’s where I keep running aground: Protecting from EMP is, at its base, a simple affair. You provide a conductive shell around what one wishes to protect. Grounding that shell, or not grounding, is a subject of debate. However, my experience with electronics indicates that if the shell is doing its job, grounding it is not a problem. It may or may not be required, or even useful, to electrically insulate sensitive contents from the conductive shell. That answer depends on to whom that question is addressed. But consensus seems to indicate that it can do no harm.

Steel is an electrically conductive material, not as conductive as copper or gold but quite conductive nonetheless. So why not use a steel drum to protect against EMP? Drums are available in “open head” design in which the entire “head” or end of the drum is removable and can be reinstalled with a suitable circumferential or “ring” clamp. The clamp is available in two basic styles: one using a bolt and nut to clamp the drum head (end cap) and drum together, and one with a locking over-center handle. I have seen both types in which the clamping band overlaps at the bolt or the locking handle, ensuring greater than 360 degree coverage of the joint between drum head and drum.

Additional Protection

If additional protection is warranted, and I suspect it’s not possible to have too much, a circumferential ring of conductive tape (the aluminum stuff duct workers use that seems much liked in the EMP protection community) wrapped over the surface of both drum head and drum prior to securing the head with the clamping ring should provide that level of protection.

The drum heads are usually equipped with a gasket around the rim, which could easily be removed and replaced with a conductive material, such as steel wool, wood stove door gasket, et cetera, should simple, tightly clamped metal-to-metal contact between ungasketed drum head and drum not be sufficient.

In short, I can find no reason why a steel drum could not be used as an EPM protection measure. They’re readily available in multiple sizes, from 16 gallons to 30 to 55 gallons. The over-center circumferential clamp arrangement allows for fairly rapid access. They can be stood vertical or laid horizontally in racks. They can be stacked several drums high if vertical. Properly closed, they’re waterproof, vermin proof, dust proof, in fact pretty much a barrier against whatever form of contamination one may commonly encounter.

So why do I not see frequent mention of inexpensive steel drums for use as EMP protection measures? What am I missing or not understanding? – NK

HJL’s Comment:

You’re not missing anything. Most people are not used to seeing them. They just don’t think of them They think smaller, like in 5-gallon increments. A steel drum does come with its own set of issues related to its size and weight, especially when full of stuff. But they are an excellent option. If you have the type with the metal band to seal the lid, you don’t even need the tape. The lid and drum usually do not have paint on those edges. If they do, it’s easy to remove. About the only thing that you really can’t use them for is direct burial.

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#1 Comment By Dave On May 11, 2017 @ 9:55 am

Please consider tracking down information put out by Jerry Emanuelson. I believe you will find that to be very helpful.

#2 Comment By grayfox114 On May 11, 2017 @ 10:51 am

JWR/HJL: With all the talk and concerns about a possible EMP attack, I have a question that SHOULD concern many, many people: I was unable to get an answer even from the manufacturer: Many gun safes are sold which use an electronic /keypad system to lock and unlock. Would an EMP fry these and render the safe “unusable?”

#3 Comment By Dan On May 11, 2017 @ 11:08 am

I have also asked that question, with no response. I remove the battery and press a couple of keys. I don’t know if that helps any, but I would also like to know the answer to this one. Thank you anyone for the gain in knowledge.

#4 Comment By Scott from Texas On May 11, 2017 @ 11:36 am

After my own research over many years it is my conclusion that electronic safes (and other small electronics) would only be affected if they are plugged into the grid (obviously not relevant with the safe you mention) or very close to ground zero, in which case you have MUCH bigger issues than EMP protection.

#5 Comment By DBCooper, From the Redoubt On May 11, 2017 @ 1:56 pm

GF 114 . IMO … Trusting an electronic keypad on a safe is akin to investing in bitcoin … great as long as it works but will it work after the fecal matter hits the oscillator !!?? Yours, DB

#6 Comment By Butch On May 11, 2017 @ 2:27 pm

Well, right or wrong, I had my safe’s electronic combo changed out for a manual.interesting….the safe tech told me that most gun safes are vulnerable from the back and bottom. Only the front is heavily reinforced.

#7 Comment By Jim On May 13, 2017 @ 11:18 pm

My Liberty Lincoln same came with an electronic “EMP-Resistant” lock. Had some sort of fancy certification statement. If you’d like more info, pls reply and I’ll get more off of the safe and paperwork.

#8 Comment By Dave in Iowa On May 11, 2017 @ 11:16 am

I was at a banking conference several years ago and talked to an exhibitor displaying electronic locks for teller drawers, etc. I told the exhibitor that the product looked a lot like what is on my guns are. She said that her company supplies most electric combo locks for unsafe in the US. I asked her if they would be affected by EMP. She was well aware of the issue and said that the company believes they would not be affected. For what it’s worth.

#9 Comment By Tom On May 11, 2017 @ 1:06 pm

I wouldn’t expect a company to admit their locks would be affected by an EMP unless they had developed a newer EMP “proof” lock. To admit that would be the death knell of the company which provides locks for bank vaults, home safes, gun safes, etc. There is no way I would want a digital lock between me and ……

#10 Comment By Ron On May 11, 2017 @ 12:44 pm

Storm what I have learned from a couple of engineers… If it’s not hooked into the grid, or in the case of vehicles, if they are not running, these shouldn’t be harmed. I have smaller galvanized trash cans for amateur radios and electronics. Just to make sure. I DO believe in Murphy’s Law.

Be safe y’all!!

#11 Comment By Mike On May 11, 2017 @ 4:07 pm

I am an electrical engineer and I concur with this analysis – the issue is not with small electronics, but with anything that is connected to the transmission and distribution system. If it’s not plugged into the wall, the risk from EMP is minimal and enclosing it within a Faraday cage is unlikely to offer any significant advantage, if one exists at all.

This also applies to vehicles.

#12 Comment By Phillip Brown On May 11, 2017 @ 12:56 pm

great idea!

#13 Comment By Lo On May 11, 2017 @ 1:30 pm

It should also be mentioned, and has on Survival blog many times, if you want to check the effectiveness of your faraday cage, put your cell phone in it and call it, if it rings, you need to work on your seal.

#14 Comment By cyclist4444 On May 12, 2017 @ 10:49 pm

My whole house is like that – Guess I am more ready than I thought !

#15 Comment By CM Dutch On May 11, 2017 @ 1:31 pm

For what it is worth, my son had his gunsafe in a horse trailer parked about 25 yards from a tree that was hit by lighting. It did not work afterwards. Took the safe into a locksmith where he put one of those devices as seen on James Bond and tried for a week to open the safe. Took him about 1 1/2 days to drill into the safe at his shop to open it. He advised to put a mechanicial lock back into the safe and claims he really likes the electronic locks – it more than pays the light bill every week. CM Dutch

#16 Comment By Scott from Texas On May 11, 2017 @ 6:59 pm

So the “near ground zero” aspect applies here 🙂

#17 Comment By Atla On May 11, 2017 @ 1:35 pm

Speaking of burying, can you EMP proof by burying electronics?

#18 Comment By Paul Seyfried On May 11, 2017 @ 1:59 pm

SolArk, a manufacturer of hardened color power systems, does its own simulator testing to 100 KV/ sq meter, has a video out showing test results. Solar panels in storage (not wired!) are immune. Solar panels with un-shielded conductors running much of any distance are degraded, but not destroyed outright. Shielded wiring on PVs solves the problem, as the signal cannot “see” the wiring. Stuff your PV wiring inside aluminum or steel conduit or flex…problem solved.
A friend of mine, Bronius Cikotas, tested many types of equipment on government simulators and confirmed what Scott said. Bron placed a dozen small radios of all types inside a standard steel file cabinet and insulted them to 50 KV/sq meter, and they all emerged in working order. Consider the generous gaps around the file drawers…yet they were protected, well enough. Similarly, there is an electronic gap in the steel hatch on my steel shelter. The hatch measures around 9 square feet, so this gap, created by the rubber gasket, involves considerable area in total. Nevertheless, when I close my 3/8″ thick door while using a portable radio or cell phone, all signals die, even next to the door. Further retreating inside the shelter would vastly reduce any residual leakage. Any exposed 12 gauge wiring (outside) will collet around 47 volts per linear foot, so any small gaps in coverage will not amount to much of a threat inside the protected area (assuming it is NOT connected to the grid!).
Tom, at SolArk, says the slot antenna effect is very overblown, so OCD taping to seal off any possible intrusion is not necessary.
If reality turns out to look similar to testing results, the vast majority of vehicles will run (if they have fuel), though many ancillary systems on the vehicle may not…intermittent wipers, radio, etc. Ignition systems since the early 1990s are shielded inside aluminum enclosures, and are not connected to the world’s largest antenna, the grid.
In SolArk’s you-tube video, the laptop computer and a i-Phone were not damaged, though the laptop shut down. It turned back on. It was running on its battery.
Attenuation factor of .100″ of sheet steel is excellent, and industrial and military Faraday cages are make using 12 gauge galvanized steel. There are three of these where I used to work and an aerospace firm. I can get more details on the attenuation formula with more time, but I did run down the formula to 3 volts, with three of the 20 reduction factors remaining.
BTW, any gaps in your steel flex shielding on your solar panel wiring can be wrapped in aluminum foil and taped on both ends with metal tape. Having a spare charge solar charge controller or two makes sense, if not just for the fact that they do break now and then anyway. Inverters tend to be isolated because they are on the other side of the battery….a sort of filter. Nevertheless, inverters are jammed with chips and are critical to making AC power. Have a spare. Recovery of the national grid and supply chain could take one to two decades. When expert witnesses, in open Congressional testimony, claim “months to years” for recovery, they know better and are filtering their comments to avoid panic (as if most Americans are taking this seriously anyway).
Survivalblog kindly posted the SolArk video a couple of weeks ago, and it’s worth watching.

#19 Comment By UnderWater Communicator On May 11, 2017 @ 2:04 pm

in practical experience electronic locks are less reliable/resistant than manual locks. Even the X09s I used in the EKMS world were found to not be very resistant.

The best way to think about your electronic lock setup is this: Big metal box with electronics attached to the outside skin. The induced current will not flow around that cheap electronic lock Like it has magical powers. It will take the path of least resistance, and if that is through the lock and electronics then that’s where it goes.

I am a big believer in good old fashioned manual locks. They last a long time and you have no worries when it comes to EMP. You won’t be standing there staring at it after an EMP hoping it works. It will.

For what it’s worth:
Sergeant and Greenleaf now offer EMP resistant locks. I believe these are options on liberty safes now too.

They have a guarantee. Not sure how you would collect on that if it fails after an EMP attack…..

#20 Comment By Anonymous On May 11, 2017 @ 2:08 pm

On the advise to remove paint from the edges of ammo cans to get a good connection, I’ve done so. I use a gasket made from rolled fine stainless steel wool. I hope it would be effective. I do wonder about using aluminum tape. Wouldn’t the adhesive have the same effect on the tape b as the paint on the can?

#21 Comment By Hugh James Latimer On May 11, 2017 @ 3:17 pm

Yes, the adhesive can have that effect. An easy way around that is to use an [2] which will ensure good electrical connection.

#22 Comment By Reject On May 11, 2017 @ 3:18 pm

I dont know about the rst of y’all. But my electronic safe also has a key lock cylinder. So if the batteries die or anything else were to happen i can still open my safe and get to my guns. I would think all safes have this as a back up measure

#23 Comment By Peter H On May 11, 2017 @ 10:45 pm

Are you sure the key lock is a bypass and not a mechanical override to keep the electronic lock from working? This is the case with Sentry fire safes with keypad locks. All the mechanical lock does is stop the handle from being operated if the electronic combo is compromised.

#24 Comment By FRD On May 11, 2017 @ 5:03 pm

James and Hugh-
I have been racking my brain as to what would be the best way to protect my propane whole house back-up generator from an EMP situation.
I thought about having a sheet metal enclosure built, lined with insulation for noise, and then placing same, with full contact, on the ground.
However what to do about the propane line in and the electrical line out, how to keep those from allow RF in?
Any ideas would be welcome…

D in the Redoubt

#25 Comment By BobW On May 11, 2017 @ 9:43 pm


I don’t pretend to be an electrical engineer, or Hugh either, but the line in would negate all that encasement.

The only way to avoid an EMP from frying your prop-gen would be to not have it connected at all. Power goes out, run out and connect.

#26 Comment By Joel Ho On May 11, 2017 @ 10:12 pm

Can confirm based on experience with EMP testing that the steel drums are fine for the shielding as long as properly sealed.

The logic issue with steel drums is that you will presumably want to USE the electronics you are shielding after the EMP. But – if somebody is willing to set off one EMP, why wouldn’t they set off another EMP a few weeks later when the backup equipment you saved is being used? Hence, your equipment needs to be shielded even while it is being used, which is the hard part. We at MobileSec do have a solution.

That said, small electronics that are not connected to the grid – say safe locks, etc – are unlikely to be affected. At MobileSec we did a round of testing where devices ranging in complexity from kitchen timers with a battery to computers were tested. Results varied widely using even the same machine – some devices are more “EMP-proof” than others. An old Nokia phone from the 1990’s, for example, would only be reset. A computer with a cable, however, was quickly fried. Basically, if there is a cable that allows for energy to build up, the vulnerability is higher. Hence why power-grid-connected equipment is vulnerable – the equipment itself is fine, but the power grid allows for a massive surge to fry things that would otherwise survive. The same equipment, without the lines, would probably be fine.

Would comment on the cell phone test – it does NOT always work. We make a cell phone blocker as well. Based on our testing, we can say that the test “works” depending on how far you are from the tower. It’s possible that you can get a signal on the phone but still be EMP shielded – it’s a matter of degree. Blocking all signal entirely is in some sense harder than blocking EMP. The problem with EMP is that the wide spectrum means that materials generally have a harder time blocking the whole gamut of frequencies, but it’s relatively easy to block ONE set of frequencies – like say cell phones – with a single material.


Joel Ho
MobileSec Solutions CEO

#27 Comment By Rex Byerly On May 12, 2017 @ 1:18 am

I might be able to offer some insight on automobiles – – I purchased a 2013 Ford Police Interceptor that had a massive lightning strike while running. It knocked out the alternator, ABS pump and the electric power steering. Beyond that, the runs and drives and only throws codes on those 3 subsystems. The ABS pump cost $60 (junkyard) and is easy to install. The alternator is $200 (NAPA) and a real pain. The EPS is $200 (junkyard) and takes an act of G-d to install. Overall, I suspect EMP will not kill every vehicle but will require some work to overcome.

#28 Comment By Don Lain (MO) On May 12, 2017 @ 3:00 am

For those who are interested in electronic locks, doors and safes as far as EMP. Don’t know about EMP, but a friend of mine suffered complete lost of digital locks in his home a month ago caused by direct lighting hit on his home. I had a hit 4 years ago and my mechanical combo safes still work great.

#29 Comment By Wigeou On May 12, 2017 @ 4:02 am

I may not understand this problem as well as I think, but it seems that for equipment to be protected it has to be sealed in the faraday cage at the time of the EMP. There will be absolutely no advance warning to give time to seal anything into a cage. In other words, anything that is being used and is connected to the grid will probably be damaged by a pulse. The only possible exception would be in the case of a solar flare where some advance warning (minutes?) might be possible. Am I missing something?

#30 Comment By Clyde On May 12, 2017 @ 9:42 pm

would a grounded steel building with metal siding and steel doors with no windows work as a fairday cage?

#31 Comment By Hugh James Latimer On May 12, 2017 @ 9:56 pm

Clyde, In theory yes, but there are some practical problems. The siding in a metal building is typically affixed with screws every four feet or so. That leaves the potential for a significant gap. You also have the issue of the ground. A good Faraday cage needs coverage on all sides, so you will also have to have metal plating on the flooring (because screening won’t be durable enough – though you could lay screening and then possibly plywood over top of that to take the abuse.)
There are a lot of joints in a metal building and every one of them is problematic. You can tape them all with adhesive backed foil, but now it’s not getting very practical. Doors are also problematic for the same reasons. They usually have rubber seals and you would need to make sure there was conductivity in there as well. Paint is another concern. Being exposed to the weather, you would probably need it to be galvanized rather than raw metal.

#32 Comment By Rich Tyler On May 13, 2017 @ 2:55 am

Here is something I have wondered about. EMP is an electromagnetic pulse. Basic science says if you was a pulse like this across a copper winding it produces electricity. That’s how an old fashioned generator works. Now, take that same pulse and pass it over a modern alternator or starter motor and you have a current. How strong it is depends on the strength of the pulse. A modern alternator would have the electronic rectifier inside of it burned out. Is this accurate and if so this is what we need to protect our electronics from and this is why we need extra alternators and starters stored in faraday cages.

#33 Comment By Greg Rush On May 18, 2017 @ 6:11 pm

You can usually purchase rebuild kits with new diodes. They are not expensive and don’t require special storage. My guess is that the current produced will not harm the rectifier circuit in an EMP event. The vehicle’s ignition system is more prone to damage. Perhaps a spare from the junkyard might be a cheap investment and have it stored in a Faraday box.

#34 Comment By Blackcat On May 13, 2017 @ 3:39 am

All I can say is the US Army does not allow any electronic locks on any arms vaults. Take that for what you will.

#35 Comment By Greg Rush On May 18, 2017 @ 6:05 pm

For what it’s worth, my gun safe has a hidden manual lock inside that’s behind the electronic keypad. I don’t understand why anyone in their right mind would want such a safe that didn’t offer this feature. EMP aside, I worry more about battery life, fire, or a theft attempt. I can only assume that the keypad will melt in a fire or be destroyed in anger trying to break inside my 800lb+ safe. I figured that I would anticipate the door wheel internals to be sheared too if someone attempts entry. If someone wants in bad enough though, they’ll find a way. Just don’t put all of your eggs into one basket! Have a couple of backup firearms, cash, and ammo with magazines stored elsewhere.

As for sensitive electronics, they don’t have to be connected to a grid to be affected. Internal electronics may contains several feet of wire coupled with solder traces. These act like antenna that will induce electron travel. Depending on the “antenna” length, the movement of electrons “voltage” will be amplified with longer antennas so to speak. Electronics with more robust design such as older AM radios will fair much better than say a modern AM radio with an LCD display and RF controlled microcircuits. I know the military has performed some EMP related studies. On modern vehicles, some cars would not start at all, some would die, but restart, while others ran, but not very well.

To say the least, any affects of EMP are not predictable. It’s best to have a Faraday cage with a few extras as backups. Some of those might be a shortwave radio, Fluke meter, DC powered battery charger, AC inverter, solar charger controller, etc. Just apply the two is one philosophy and store the extras accordingly in case of an EMP.