“The exercise was held from May 8 to 9, 2024, at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and at a Federal Emergency Management Agency (FEMA) site in Denver, Colorado.”
Article refers to a PDF of the report it’s based on:
https://www.jhuapl.edu/sites/default/files/2025-04/Space-Weather-TTX-Report-Summary-v3-FINAL.pdf
I’m glad this threat is at least starting to be taken seriously. As an amateur radio operator, I got incredibly interested in how the weather on the sun affects radio propagation and power management here on Earth.
Better a CME than an EMP just simply because there is at least some time to prepare for a massive CME. Whereas an EMP has absolutely no warning whatsoever.
In the event of a massive CME off-grid homes and buildings are likely to fare much better because they are not connected to the power grid. The problem comes with long transmission lines where incredibly large charge differentials can build up over distance. shorter wires can’t build up nearly the same amount of charge differential.
Edit: I feel it’s important to mention that grid tie systems are going to be just as vulnerable as on grid because you still have the grid actually physically connected to the building.
It’s worth noting that even though a building might have solar, the systems usually disable themselves in the event of a blackout to prevent back feeding into the grid.
That’s known as a grid tie system and my edit mentions that. The only way it’s going to help is if the grid is physically disconnected from the building as in the wire is not connected to the building at any point.
Unless I’m missing something here, thats what an LVD should do, and anyone grid-connected with solar should have.
During a normal power outage, you’re right. That does keep you isolated on your own island. But in a case like this, the voltage is likely to spike to incredibly high levels on wires that aren’t meant to carry it and cause arcing and possibly fires. That’s why you want to be physically disconnected.
The breakers at transformers in each neighborhood would surely trip before frying a house I would think.
They go whenever a tree comes down near our street anyway.
The voltages involved are more likely to cause the transformers to explode rather than just tripping the breakers.
Got it, at that point (extremely high voltage) you’d need suppression at the panel. Which I would hope people have inline, but not expect like an LVD.
With a high enough voltage the air will ionized and the power will literally jump over many protection mechanisms. Also it can cause certain dialetrics (electrically isolating materials) to break as they all have a breaking point.
An extreme enough event can be way beyond even the biggest of tolerances of safety systems as there is some distance between where the outside end and the inside end are wired into the system and that distance is chosen with certain maximum voltages tolerances in mind which are finite and beyond those design voltages and as I said the air will just ionize becoming conductive and many isolators will just blow up.
So it makes sense that when a massive electromagnetic storm is inducing electric currents along tens or hundreds of miles long wires, the only guaranteed safe system is to not even have a cable from the grid coming into your house.
At that point, that grid connection will be the least of anyone’s worries. The storm in Quebec in… 1990? Ish. tripped breakers, and shut things down for like a day.
A storm on the scale youre talking about I am pretty sure would wipe out satellites (maybe even take them down due to atmospheric drag?), impact cables other than power like copper laid for internet and phone, etc. Grid-connected power or not you’d be severely impacted and potentially at risk.
Oh yeah, a large enough solar mass ejection in such a direction that it would directly hit planet Earth would be extremely bad.
That wouldn’t be an off grid building then.