In our house potential difference : 240 V
Current : 5 - 20 A
This means the line wires that are entering the meter have a potential difference of 240 V The minimum and maximum limit of current that can be drawn from the mains is 5 - 20 A.
When the current drawn from mains is more than 20A. Overheating occurs and may cause a fire. This is called overloading.