EMP Ferrites

From $7.00$20.00

The ferrites offered here provide excellent suppression of energy from a broadband pulse, like that of an EMP. Select a size that will clip around your cable — too large is okay, but not too small. Looping the cable through the ferrite helps to further reduce the transient, see video below.

Special Pricing on multi-ferrite sets – Click “Bundles” above.



Ferrites are ceramic compounds that consist of a mixed oxide of iron and one or more other metals. They have long been used to protect sensitive electronic equipment from conductive transients. Ferrites offer a simple, but effective, way of protecting items that must remain plugged in, such as solar panels, charge controllers, generators, computers, or amateur radios. They can even be used on some automobile wiring. They are very simple to use. Simply click them around the cable feeding the sensitive item. That’s it!

Keep in mind that not all ferrites are equal, and certainly not all will protect from an EMP. With a PhD in electrical engineering, I was able to evaluate hundreds of potential ferrites, and the ones offered here are the best I could find anywhere! They meet these important criteria:

  • Comes in various sizes to better fit cables
  • Provides broadband protection, exceeding 1 GHz
  • Offers the highest resistance to better suppress transients
  • Snap-on for easy installation
  • Reasonable cost


Please see the FAQs section to learn more about how ferrites work and how they are used.

1. How does a ferrite work? When clipped around a cable, a ferrite forms a passive low-pass filter. That means that it won’t affect low-frequency signals (such as power, charging currents, and low-speed communications), but it will suppress high-frequency signals, such as glitches, sharp pulses, and other transients. The geometry and electromagnetic properties of the ferrite material determines how well it will work and across what frequencies.

2. What can they be used for? Ferrites can be clipped onto cables feeding sensitive electronics. In fact, ferrites are used every day on cables for laptops and other electronics. They can be clipped around power lines and cables that have low-frequency signals.

3. How well do they work? A ferrite’s effectiveness is determined by many things, including its material, its geometry, the frequency of the signals on the cable, and the impedance of the load. They work particularly well for low-impedance systems, such as power systems.

4. Do you make the ferrites? No. I simply resell the product that I found to be optimal for this application.

5. Can I trust that these are the best ferrites out there? I reviewed several hundred ferrites, and these were the ones that I believe would best suppress the energy generated by an EMP.

6. How big are they? I’ve put the dimensions of each ferrite in the Buy Now menu. Be sure to pay particular attention to the Inner Diameter. Ideally, you would want it to be slightly larger than your cable’s diameter — definitely not smaller, or it won’t snap closed.

7. What wires should I clip them on? My recommendation is to clip them on every wire going into or out of a sensitive electronic system. The only caveat to this is that you don’t want to use them on high-speed digital lines (such as local area network cables) or some automobile engine control wires because they may interfere with their operation. The most general use of ferrites is use them on power wires.