How much electricity does consume electric system by itself? Just to have an option at any moment to plug in anything at socket at home and turn it on. There are huge power plants to convert high voltage to much lower values (220/110V) and off-course they are with energy conversion efficiency < 100%.
What will happen if suddenly huge amount of power consumers just turn off EVERYTHING. (For example - Earth Hour, but not just the simple citizens turning off few lamps - completely everything, all huge factories, trains, traffic lights, street lights - total consumption blackout).
And the situation is - the electricity production is the same, but the only working unit is electrical system by itself - nothing plugged in, but it is functional.
Does the power grid something like huge heaters/huge engines - just to consume excess of the electricity power and keep system online without damaging?