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EMP Facts and Myths

At a lot of shows I attend, there are some questions I hear very often. I would like to set the record straight on a few points because the amount of information, both good and bad, in this field is huge. EMP FAQ’s & Myths Q: Do Faraday Cages need grounding? A: No. A Faraday cage designed against EMP, if properly constructed, will keep any charge outside the shield. The shield interior is separate, so anything inside, even though it touches the inside of the shield, is safe. However – if the cage is improperly made and there are wide holes in the mesh exceeding the size of wavelength to be blocked, grounding could help. As an example – This Youtube video link is of EMP testing my company has done with another firm’s professional EMP simulator. You can see a shielded laptop on the left and an unshielded laptop on the right. The left laptop, although you cannot see it due to the lighting, was not affected – in other words, grounding was not necessary at all. The right one was shut down – hard to see, but visible. This also shows you the probable impact of EMP on a computer – just a shutdown – IF you do not have wire connections to the computer, like a USB mouse. With connections, the damage can be much greater. Q: Do you have to insulate electronics inside a Faraday Cage? A: See above. You don’t need insulation for electronics inside a properly constructed Faraday cage. There was no insulation and the computer was fine. Additionally, your electronics are usually in a plastic casing – so they are already insulated anyway. Insulation doesn’t hurt, however. Q: You have to have an EMP-proof car to survive. A: Your car will probably ok. If you were not actively driving at the moment of the strike, you are even more likely to be unaffected. From the EMP Commission report: “We tested a sample of 37 cars in an EMP simulation laboratory, with automobile vintages ranging from 1986 through 2002. Automobiles of these vintages include extensive electronics and represent a significant fraction of automobiles on the road today. The testing was conducted by exposing running and nonrunning automobiles to sequentially increasing EMP field intensities. If anomalous response (either temporary or permanent) was observed, the testing of that particular automobile was stopped. If no anomalous response was observed, the testing was continued up to the field intensity limits of the simulation capability (approximately 50 kV/m). Automobiles were subjected to EMP environments under both engine turned off and engine turned on conditions. No effects were subsequently observed in those automobiles that were not turned on during EMP exposure. The most serious effect observed on running automobiles was that the motors in three cars stopped at field strengths of approximately 30 kV/m or above. In an actual EMP exposure, these vehicles would glide to a stop and require the driver to restart them. Electronics in the dashboard of one automobile were damaged and required repair. Other effects were relatively minor. Twenty-five automobiles exhibited malfunctions that could be considered only a nuisance (e.g., blinking dashboard lights) and did not require driver intervention to correct. Eight of the 37 cars tested did not exhibit any anomalous response.” Q: Won’t solar flares end everything? A: If we have an extreme solar flare like the Carrington Event, there is a big chance of damage. What is left unsaid is that utility companies are working to ensure continuity of service. How effective they are is unknown – but the US government already has active early warning satellites. The plan is to notify utilities in advance so that measures can be taken to minimize impact. While these measures are apparently effective so far, there are two areas of concern – 1) instead of hardening the system, our protection relies on utilities taking the right steps every time, bringing the human factor into play. 2) A larger solar flare event could cause significant damage beyond anticipated levels, and there is a scarcity of data on this subject, at least in the unclassified world. However, utilities have hopefully learned from the Qeubec area solar flare of 1989. Q: Will my phone/iPad/electronic device be affected by a solar flare? A: Not unless they are connected to long conductive cables, antennas, or power lines. If you have a device like an iPad, unconnected to anything, it WILL NOT be affected by a solar flare. There is simply not enough energy to break through the devices’ internal EMI shielding (which are there to protect the various device components from affecting EACH OTHER). Q: The military has done extensive research on this topic, won’t it all be fine? A: While testing individual devices and components, and even vehicles has been done, there has been no testing on a whole-system level of, for example, a city with a power plant. So while individual components might be affected, the exact level of damage is unknown. A grid exercise was conducted last November to try to simulate damage, but this is nowhere near the actual real-world experience necessary to understand the practical effect of EMP. Q: Complicated electronics are very likely to be damaged, so my laptop is very vulnerable. A: In general, the more complicated an electronic device is, the LESS likely it is to be damaged. While at the circuit level, a laptop is relatively vulnerable, one must remember that the laptop components – hard drive, CPU, etc all have some level of EMI shielding to protect from interference by the other components. This makes laptops relatively tough. On the other hand, simple electronic devices like a solar cell calculator don’t need EMI shielding so are actually more vulnerable in reality - assuming that you don't have outside connections or antennas to your devices. If you have any thoughts or further questions, please email them! We would be happy to answer them.

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