I think I'm hearing put your electronics in a steel box that is grounded and then put the steel box inside an aluminum box (might as well ground that too) in order to be really safe but there is a high probability that won't work either? So how do airplanes get hit once a year on average without major issues? I'm going to grill the EE's in my plant and see what they say. Stay tuned.
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I've been hit twice in my aircraft. Once no damage inside, just a blackened pin hole where it exited. Another time, it blew an antenna coupler off of our HF antenna wire, and charged the intercom system with static (deafening noise) for about 5 minutes. In general, since the aircraft does not provide a path to ground, the damage is only from the static discharge as opposed to a sailboat with our nice metal masts providing a perfect discharge and aggregation point as well as all of the tasty electronics on board. There we get the double whammy of conductive and inductive currents on top of a massive static discharge within a small area. Not to mention the heat, and fracture points caused by the shockwave. This noise alone can crack small circuit boards, the static can jump circuits and toast transistors, and the main current discharge tries to pump hundreds of thousands of times the volts and amps that our meager 12V wiring was designed for.
Dan
The large pulse associated with a lighning bolt has frequency components that span a very large segment of the frequency spectrum. Those frequency components that have wavelengths on the order of the size of the wires, printed circuits, etc., etc. that are in the inventory of most yachts will couple with the equipment and set up large AC currents. Further more, a single isolated wire can conduct current if it is acting like an antenna.I too say sorry to hear such bad news.
But as I'm redoing some of the 12v stuff and adding electronics it has made me start thinking.
In practice one of the things that helped reduce the damage in my radio studios was that every interconnected piece of equipment had a common chassis ground of decent size (say #14 at least). Not relying on power leads, or the "ground" lead in any interconnect cables. If that's done once the big magnetic field rams through the place, everything rises and falls together. And that reduces the high current flowing between the individual devices on the interconnect cabling.
So I can see that I'll be adding a flock of MOVs across the power leads, maybe zeners on the data leads, and a nice common buss.
Good possibility that it was a 'bolt' going across the top of your boat .... and your boat sent a leader 'up'. After I was struck for the second time, and in the same manner (no fuses, etc. blown) Im considering to put fuses on the all the GROUND system. Plus Im considering 'polyphase' 1Mhz chokes on all the wiring that feeds the 'sensitive' stuff for to help control the EMF/RF 'stuff' .... like on my 'seatalk' system.
Many home appliances are controlled with microprocessors. The service manual requires the technician to wear a static ground strap while working on the control circuits.You don't need a circuit ground to conduct a current and you don't need large amperages to blow sensitive electronics. All you need is a potential difference within a circuit and enough current to exceed specs. For modern chips and boards, that may be a small bar to pass. I wonder if some sort of shielded cases might be the way to go for the person determined to fend off Mother Nature and Father Physics? btw, thanks for the link.