Emps, lightning and surge suppressors

Some thoughts / information I've built up over the years with this stuff.  Ignore, laugh, mock, deploy foil hats as necessary 🙂

IMO the only EMP that there is any point in trying to defend against is lightning.  There's no point in trying to defend against a nuclear bomb that is deliberately set off high enough up to be intended as an EMP weapon as the widespread disruption any such attack would have on a country would have one far more worried about where food / water / medical needs are going to satisfied from.  If one is a prepper dry goods, self contained meals etc, would be a large part of the food cache rather than deep freezers full of animal parts that require an electrical supply.  If a solar event pushes a damaging CME our way there'll be plenty of notice available from all the space borne monitoring that is currently in place to allow safe disconnection, and an object striking the atmosphere that is big enough to cause a decent EMP will see humanity wiped from the face of the planet anyway.

Unloaded runs of wire can have quite high voltages appear across them if there is a decent strike within 1km so that is something to be considered, as is local ground step (ground rise, step potential, what ever name you like to put it under) from a strike within 500m as 100kA tends to do that.  That means you can have significant voltages appearing across things in unexpected places.  Weather services and just taking a look out the window will say if there is a lightning storm coming, and if there is one, unplug the array, and place a shorting plug over both open leads.  Use protection devices certainly, but if it's known a storm is coming a little bit of prevention is a good thing.  Unplug stuff.

Magical claims that a small box fitted to the switchbox / breaker panel, will save you are just that, magical.  Yes, these devices will improve the chances of equipment surviving a lightning strike that happens on the supply side wiring system, the electricity network etc but fundamentally do nothing against a strike to the premises where heavy currents are induced directly within the premises wiring.  These devices work by clamping the voltage difference across all the protected wires including ground.  It's a concept that can be known as the protected bubble.  All protected conductors rise and fall at the same time ensuring there is not sufficient voltage between them to cause problems.  For the bubble to work there absolutely has to be no conduction path outside of the bubble downstream from the protection device.  If there is, game over.  That means telephone line, TV antenna, any potential spark gaps, etc.  If it isn't clamped by the device it must not be present downstream.

The protection device needs to be both really fast and capable of handling really high currents.  Big telcos etc have done lots of research on this stuff.  There's quite a lot of useful information available on the internet explaining the race that starts once a strike happens.

The earthing system for these protection devices must be up to the task too.  Can it sink 10kA in a millisecond?  This means a really decent earth system (rods, mesh etc), and beefy cabling with no sharp bends and definitely not wound up, spiralled or other silliness.  Sharp bends or any sort of loop causes significant impedance problems as it increases the wire inductance.  The average households earthing system is woefully inadequate.  A good idea of what is involved in real lightning protection can be obtained by watching any of the number of youtube clips touring television transmission sites.  Take note, every rack is bonded together, all earth conductors are beefy, all bends are gentle and it all goes back to one central grounding point in as short a run as practical.  The whole facility is a bubble so that when a strike happens everything inside the bubble goes up and down at the same time.

The best mitigation would be to equalize the voltage across the whole system as quickly as possible. Surge devices sacrifice themselves and clamp everything together hoping to shunt the induced current around the device you want to protect. Putting one at the service end of the supply (utility or PV), one at the overcurrent device, and one at the point of use is pretty reliable for induced overvoltages. But it still takes time and branch circuit wires are small, so relative voltage drops can be pretty big still.

Commercial lightning protection systems use multiple runs of 3/0 copper. The goal is to make the whole system a low impedance path that can move a bulk charge from one place to another quickly, thereby limiting the potential between two points. Having a surge trap at multiple points along a circuit helps. If you could afford to build a ground ring around your house as big as possible, then surge devices on the circuits, and even Faraday cages around delicate systems would be great, but man oh man the effort and expense.

Well I expected to get blasted, and so I did.  I will say that I earned my tin foil hat and am (mostly, secretly) proud of it!  Btw, tin foil hats have been claimed to help deflect haarp transmissions and protect against the emf from power company meters.  I do other unpopular things too.  I refuse experimental dna altering drugs passed off as vaccinations, don't believe it's a pandemic when there's a 99.97% survival rate, don't wear a face diaper (despite the crazy old lady yelling at me at home depot), don't believe Russia is to blame for Hillary losing in 2016, and don't believe Biden is legitimately in office  or that he has two brain cells still firing. 

I'll say again, regarding suppressors, I do believe doing something is better than doing nothing.  They may not work.  Then again, they may leave me in a better position than the 99.9% who do nothing.  When WW3 starts in approximately 4 weeks (some say its already started) we will probably know.  At least I will.

I've got to go polish my hat....

I wouldn't call that a blasting. I mean, I agree that surge protectors are useful. They just aren't nearly as useful as the manufacturers want you to think and certainly nowhere near as good as equipotential bonding.

What's going on in 4 weeks?

The Naval Security Group even went as far as having special carpet made. It had copper wire for a good part of the threads so that even the flooring was a blocker of signals in or out including lightning induced EMPs. But guess what all the fancy equipment could not stop?  Ball lightning. Never saw it at my last work sites but did when I worked directly for the State. You'd be surprised how wide a door becomes when two people exit a room at the same time because of it being in a room. Dad had also seen it in his work with the NSG. The USACE installed grids under our pavement for grounding of the radio tower and all of the electrical. Our outdoor metal steps, fences, railings were also bonded to it. Instructions were that during a storm, you did not step from the lower step to the ground, but instead jumped from that step to the ground.  Level was only about 3 inches difference but still.

Back when MOVs first came out cheaply we had instructions from higher ups to install them in all of our breaker panels. One lightning strike was all they were good for as it would take them out. But they did protect some rather expensive equipment from that strike. It became routine to check them after every storm where we had a close strike. We knew if they had been close even if we weren't there at the time because we were one of the lightning monitoring sites for the NWS. Our house has been hit twice in 42 years. Doesn't help that we are a two story house where the only things taller are towers, power lines, and Palm trees. Our home in town was always getting hit to the point where the insurance company refused to pay off on one claim until the house was inspected by the local power, cable, and phone companies and an electrical inspector for the city. When they found that all met code, they had to pay off on a new oven, TV, clocks, microwave, and stove. The strike actually blasted the oven element into the glass in the door. That one strike also took out a string of the cable company's amplifiers and were traced back to entry at our house. We know what the side effect can be on even equipment that is not plugged in can be Ever see a Color Computer CRT after a nearby strike? Pink and purple and blue when it should only have shown blue. Degaussing cured that but that piece of equipment was not even hooked up when the lightning struck.