Advance countries like US, Canada and Japan have their single phase ac power consumption level at 110 V .
Rest of the whole world consumes single phase ac power at 220 V .

• It requires double the magnitude of current to deliver the same amount of power as at 220 V
• Hence for the same magnitude of I²R losses to limit the conductor or the insulation temperature to 70° C (for PVC) , the resistance of the distribution cable should be 4 times lower. Therefore, the cable cross-section area has to be increased four folds.
• Four times more copper requirement, dumped in the building walls is an expensive venture.
• Due to higher magnitude of current, higher magnetic field in the buildings . Not good for health.
• With the installation of modern inexpensive protective devices (earth fault relays), 220 V is equally safe as 110 V

Rated maximum temperature of cables:

• It is important to understand the current and voltage carrying capacities of a conductor separately. While the current carrying capability is determined by the conductivity of the conductors, directly proportional to the area of conductor cross-section, the voltage bearing capacity depends upon the level of insulation provided to the conductor .
• The current carrying capability in turn is determined by maximum permissible temperature of the insulation or that of the conductor.
• The real power loss, I²R and the rate of cooling determine the temperature rise of the conductor which should not be more than the maximum permissible temperature of the type of insulation provided on the conductor .
• Hence, not only electrical but thermal and mechanical properties of insulation are important in power system .