[palmer]

20 volts per km from the 1921 event: http://pages.erau.edu/~reynodb2/ep410/OdenwaldGreen_Superstorm.pdf The Carrington event was higher but not that much higher. A household wiring length or even a neighborhood grid would still only develop trivial voltages.

[Rebelbase]

Yeah, but what if it's a really yuge solar flare?

[PA Engineer]

The Carrington event was not a one off partial second occurrence. It happened over a period of 4 days. The electrical shield of the earth was also stronger at that time than now.