The only data about the Carrington event is very niche.

Telegraph lines make very good antenna for the EM that comes from either CME or EMP. A shorter "antenna" would not work remotely as well. This is why most of the horror stories you see in movies are simply wrong. No, your cell phone won't die. No, your car won't be zapped. Only things connected to really long (wavelength-long) antennas like the power grid. We don't have telegraph or even many wired telephone lines anymore. Fiber optic is "hardened" by definition.