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Lightning rods are called lightning rods but they are not actually designed to take a strike head on.

They are actually designed to remove charge from the clouds above where the rod is installed.

Static electrons loves to congregate in small places, I.e. the tip of a needle or the edge or fold in a piece of metal (can help the paint job add extra paint to those places it is needed most, bonus!)

Anyway a lightning rod is probably the best protection but yeah the copper would vapourise if it.was actually hit, causing a fire.

This is false.

I'm entirely unsurprised by hn's voting on the verbose completely wrong comment and the short completely correct comment. Neither of them provided any support for their claims, but one was wrong and wasted a lot of people's time. And even worse, some of those people are now likely to go off and share that exact same wrong information just as confidently somewhere else.

Please elaborate on why.

According to wikipedia [0], such a device was actually proposed by a priest in 1754. The theory was more or less as you describe. But there is debate on whether it counts as a lightning rod, and apparently most lightning protection systems work exactly the way you said they don't: to provide a very low impedence path for the current to go safely to ground, which is called a Franklin design.

[0] https://en.m.wikipedia.org/wiki/Lightning_rod#Europe

A lightning bolt carries a current upwards of 100,000 amps, and has upwards of 10 billion joules of energy.

How many gigawatts is that? I’ve a car I need to jump start.

About 1.21 jigawatts

What the hell is a jigawatt!

I guess you aren't ready for it, but your kids are gonna love it.

Hey man if you ever have kids and one of them, when he's eight years old, accidentally sets fire to the living room rug -- go easy on him.

Enough to travel back in time afaik

Only at 88mph...

As we don't have long cables, guess we'll have to time it perfectly.

About 1,000 gigawatts peak power for a few microseconds, plenty to jump start your time machine.

That's a blast from the past - when we were kids in India we were warned never to use the telephone during a thunderstorm - my mom even used to immediately unplug it, the TV and the refrigerator during such weather.

I've had a neighbour which had her computer destroyed by lightning. She bought a new one and disconnected it during all thunderstorms from power. But she didn't disconnect her modem from phone line (it was in 1997). After another thunderstorm, modem stopped working. When I pulled it out, the main modem chip had a nice hole with some copper vapourised near it. So, unplugging telephone in some areas is a good idea. Now my whole town has proper protectors and I didn't have any problems with electric equipment since years.

At least in Germany, surge suppressors are hierarchical of type 1, 2 and 3. Type 1 handles the major blast, followed by type 2 to protect the installation and type 3 for sensitive electronics. The OP apparently just had a type 3 surge suppressor that unsurprisingly blew.

Afaik the proper way is having a proper lightning rod together with the aforementioned cascade of surge suppressors. And of course a PE!

Yup. The amount of energy from a direct strike is simply too much. It already travelled a great distance through a highly resistive material (air), even if there is an "ideal" path to ground some energy will find its way.

Consumer grade suppressors are meant for indirect strikes, overhead lines near you, or a direct hit on your neighbour's house.

How about a circuit that disconnects the wall sockets upon a strike? If you make the length of the cables to your sockets divided by the propagation speed much longer than the time it takes the control signal, it could work, no?

No relay in the world is going to switch fast enough for this. I'd love to be proven wrong though.

Good luck breaking a circuit when dealing with lightning discharge conditions.

That is unless are okay buying oil immersed equipment the size of a fridge. And that’s probably not enough, either.

Not only is no circuit fast enough to disconnect in time, lightning isn't AC/DC. It's electrostatic. Which means it carries and induces potentials that can jump further than your power usually can. So it'll bridge the connection in even circuits that were already disconnected.

By it's very nature, lightning is high enough voltage to leap an air-gap

You only have to make the gap larger than the gap to a well-grounded terminal.

You're assuming it won't bifurcate and jump across both gaps, which is entirely possible.

sadly it won't work ... the lightning will go around the switch through the air, just like it did all the way down.

Edit: spelling

So if you unplugged your computer the lightning would still find its way, through the air, to your computer?

It could if it was still part of the lowest resistance path to ground. Electricity is like water, it wants to flow from high potential difference to low potential difference.

Lightning (as far as I know) does not have consciousness and is not out to get your computer!

The parent post was talking about putting a automatic switch in between the power supply to the house (ground active neutral) and switching it off when lightning struck, the problem there is that the switch will not do much if the lightning air gaps around it.

Isn't it more likely that the current will go from one terminal of the now unconnected cord to another terminal of the same cord?

It all depends on the what is the shortest path to ground.

Ground is also a relative term for a lightning strike.

When lightning hits the ground, a potential field emanates from that point. The further out the closer to 0V the potential difference is.

As such it depends on where the strike is in comparison to the house, your wiring, where your house is grounded etc.

For example, if the grounding point on your house is very close to the strike, your house ground will be raised to the voltage of that point away from the stike.

The path to 0V may be through your active wiring, your powesupply, the house frame or the water pipes.

So yeah, hope that helps

You're a true inventor with a perfect grasp of the principles, that's basically how circuit breakers work! The challenge is to predict the future: sense how high the voltage pulse will rise, before it overloads. The speed of light is hard to exceed, at least as we currently understand. The charge will look for a shorter path, so if it can find a way around the long cable, the lightning will probably strike there instead.

Now here's one for the engineers. We can tell the future. Musicians change tempo before singing the next verse. ADS-B data tells us when there's a plane coming. Could a "smart" surge protector include a measure of ground noise, to sense local charge differentials, and guess that the next spike is probably lightning rather than a typical mains arc? More sensors yes, but increasing protection only when expected would possibly improve the feedback loop.

you are incorrect. a whole house surge protector will stop a lighting strike. its what they are designed for.