Some appliances are not actually switched off with its own on/off switch.
Use energy meter to find out which appliance cost you even you are not
using it, then use external switch or unplug it to turn it off completely.
Some appliances consume more energy to operate when it becomes
old. Use your energy meter to read the actual energy consumption states
of your device, you will know whether it is time to replace a new
appliance to save your electricity bill.
Added security is featured with the overload warning function.  The
built-in buzzer will sound when the actual energy supply exceeds the
preset safe load.