Letter Re: The EMP Threat and Electronic Gun Vault Locks

In looking at your blog on survival it revealed to me a major problem with safes with digital combo locks. If there is an EMP, those locks would most likely be fried and one could not get to guns, funds, et cetera! Do you know of a process or method of guarding against this? Is there some shielding that can be put around the combo unit that will protect the electronics? Thanks. – R.C.

JWR Replies: This blog topic seems to pop up just as regularly as dandelions. I’ve mentioned the following several times in SurvivalBlog, but it is worth repeating: A steel gun vault body itself makes a decent Faraday cage. (Although a finger mesh RF gasket at the door perimeter would make it even better.) All that you really need to add is a flat steel can (such as a peanut can or Danish butter cookie tin) to cover the safe’s electronic keypad assembly. Taping the can on works fine, but it will look tacky. A hinge attached with epoxy to a tin (allowing the can to swing to the left or right) might look better. Ideally, the tin should be grounded to the vault body. (Again, this looks tacky, but there is no way around it if you want a fully effective Faraday enclosure.)

If EMP is a major concern where you live (i.e. if you live within 250 miles of a major nuclear target), and your vault has an electronic lock then you should use silica gel rather than a 120 VAC rod-type dehumidifier inside your vault. This is because the power cord for a dehumidifier can act as an unintentional antenna that might “couple” EMP to your vault’s electronics. (One of the major no-no’s with Faraday cages is to have any conductor that can carry RF penetrate the cage or container body.)

And, needless to say, to have a gun vault lock that is absolutely safe from EMP, the next time that you move, you should sell your current vault as an included “bonus feature” with your house. Then, after you move, replace that vault with one that has a traditional mechanical combination lock. Coincidentally, I should mention that I prefer S&G Group II locks. Oh, and speaking of moving, I prefer Zanotti Armor brand six piece gun vaults that can be disassembled for ease of transport. We have a Zanotti ZA-III six-foot tall vault here at the Rawles Ranch that we’ve moved several times over the years.