When should I turn off the main power and unplug the sewing machine?

You should turn off the main power and remove the plug when you are away from the machine, after using the machine, when the power fails during use, when the machine does not operate correctly due to a bad or disconnected connection, and during electrical storms. Unplugging the power cord when the machine is not to be used for a long period of time is also recommended to prevent fire. (Page 1)