Depending on where you live, the electric power can go off anytime of the day or night with no advanced warning.
Many times you can call the power company and they will have no idea why the power is out or when it will come back on?
It is one of those things you have to live with in Thailand.
Or better yet get yourself a gas generator to use when the power does go out.
The electric company is not known to be the speediest to get the electric service up and running.
A power outrage can run into a couple days.
Best to understand and have a plan for yourself if the electric does go out.