During the coldest day of the year a couple years back, the experts decided they’d cut power for half an hour randomly around the area to save the extra power usage. What happened was they forgot to turn some areas back on and others blew transformers when they were turned on. Imagine that mess on a large scale.
The radio show I was listening to the other night had folks calling in saying they will be turning power off on the grid although the article doesn’t specifically say this. A lot of the very large transformers, from what was said on the show, are old and only a few exist in a form that can be used .... if they have major transformer issues, new ones would have to be built. I have no idea how much of this is accurate, but it seems warm weather would be a better time to do a test if there is a chance folks will be without power for more than a few hours. After going through some long outages in the past due to ice storms, if we get a major grid failure for any length of time, most folks will not fare very well. Electricity is pretty much taken for granted these days ... folks are amazed when the gas pumps don’t work and neither does the ATM!