If you own a freezer and the power goes out, do not open the freezer! Sooner or later there will be a problem, whether it's a winter ice storm or a summer thunderstorm, and that leads to questions about food safety when the freezer fails or is accidently unplugged. If at all possible, wait until the power is on before opening the freezer door. Each time the door is opened, it increases the interior temperature and decreases the time foods will keep safely without power.
In most cases, a full or nearly full chest-type freezer, in an appropriate location, will hold well for 24 hours or longer, if the door hasn't been opened. If it has been less than 24 hours, do not open the door when the power resumes. Let things refreeze at least 24 hours before opening the door.
In case of a power outage or an unplugged freezer, it is helpful to know the temperature of the thawed food. The easiest way is to place two or three ice cubes in a plastic freezer bag and seal. Keep this in the freezer at all times. In an upright freezer, you can have a test bag on each shelf. If there has been a power failure, you will know if the interior temperature was about 32 degrees if the cubes melt. If the cubes are melted, quickly determine the temperature of the water in the bag (from the melted ice cubes), and you will know the temperature inside the freezer.