What voltages are used in different countries and why?

When electric power was first being pioneered, there were two main players – Thomas Edison and Nikola Tesla. The two men had different approaches to power generation – Edison favoured 110V DC current, while Tesla worked with 240V AC current. Although Edison’s preference for DC was eventually proven to be ineffective for power transmission over long distances, safety concerns about Tesla’s higher voltage (admittedly fuelled by a PR campaign led by Edison, which included electrocuting a live elephant), led the US to adopt Edison’s lower voltage, resulting in a 110V AC power network. However, in Europe, most countries chose to adopt the higher voltage AC current that Tesla had proposed. As the age of colonialism continued, colonies tended to adopt the power transmission standards of the occupying country, which explains why various groups of countries use very similar voltages – while others use a different, yet similar to each other, set of voltages. As a consequence of this, the cables that different countries must use to transmit power over long distances, and from power networks into people’s homes and workplaces, all need to be slightly different in order to balance performance with safety. 

According to the IEC the list below is of the standard 'residential' voltages used around the world: