Building a Faraday Cage – Why and How

35 comments

A Faraday Cage, in case you haven’t heard of it, is a cage built from a metallic mesh that will prevent any EM fields from entering or escaping the space within. That’s nice to have in case someone fires off a nuke somewhere within 100 miles, or if some insidious nation actually comes up with an effective EMP weapon.

Wikipedia says it like this:

“A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static electric fields. Faraday cages are named after the English scientist Michael Faraday, who invented them in 1836.[1]

A Faraday cage’s operation depends on the fact that an external static electrical field will cause the electrical charges within the cage’s conducting material to redistribute themselves so as to cancel the field’s effects in the cage’s interior. This phenomenon is used, for example, to protect electronic equipment from lightning strikes and other electrostatic discharges.”

So why would you want one, or need one, unless you’re a computer technician testing highly sensitive equipment for, let’s say space travel?

An external electrical field causes the charges to rearrange, which cancels the field inside.

Well, there are a number of reasons why a Faraday Cage is useful to many people – including the likes of you, dear reader. Faraday cages not only block cell phone signals, radio waves and static, they also (if constructed correctly) block out potentially harmful waves that are currently travelling in your windows and walls, and through you and your precious cells. In these days of 3G networks, with 4G coming up, the debate is running high about whether or not electro magnetic (EM) radiation is damaging. A Faraday Cage can actually eliminate such radiation in your home.

In addition to the possible health benefits, a Faraday Cage will also be a very good idea if you’re planning a safe room in your new house, or adding one to that planned renovation you’re starting. Blocking EM transmissions might seem like a bad idea if you’re trying to call for help, but a land line (or more) is much harder to disturb or tap than a cell phone – remember that if you’re in

Portable Faraday-cage

the cage, EM signals from the outside can’t come in and disturb equipment that you have set up in there, in order to communicate or monitor the outside world. Hard lines are your best bet, and if you have several, then whoever is outside trying to get at you will likely miss at least one of them, while it takes only a single signal jammer to knock out all your wireless stuff.

 

How to build one.

There are actual companies that can do this for you – no surprise there, since there are companies that do just about anything these days, but this is one that you can actually do yourself, or get that contractor you already hired to do for you.  Here are some easy (and refreshingly short) instructions from an actual physicist:

Big-ass Faraday Cage

“[Use] enameled magnet wire spaced 3″ apart horizontally. Across these are random crisscross wires creating an x pattern. Next each intersection the wire is soldered, then across the middle set in a strip of 12 ounce copper sheet 12″ wide. Lay this around the center of each plane (i.e. wall and ceiling.)

Solder connect the wires at random points to the sheet. Use wide strips of the copper to connect all the copper sheets together bind and solder. Then attach a heavy copper cable to a ground rod outside the building and bind and solder the cable to the copper sheet. Then sheet rock over it to hide it from damage and view. This cage is designed to absorb a wider spectrum of energies than a conventional Faraday cage.”

Essentially, that’s all there is to it. Remember that for electrical work, you need a licensed electrician, and the rest of it you had better have at least the help of an experienced contractor to do.

Other than that, good luck with your new Faraday Cage, and EM-free living.