# Variance in Electrical Infrastructure by Country

The Country Similarity Index attempts to quantify how similar countries are to each other relative to other countries. The index is a statistically-based way to measure this. 20% of the index is based on technology. 10% of a country’s technology score (2% of the overall Country Similarity Index score) is allocated for the country’s electrical infrastructure. The following are the statistics that were included in the calculation:

## Electrical outlet

The type of electrical outlet used in a country tends to be highly regional. Since the United States uses Type A, B most North American and countries around the Caribbean have followed suit. The British used Type D and later Type G outlets, so many of their former colonies have adopted one of those outlets. One exception is that Australia popularized Type I outlets in the Oceania region. In Europe and countries that were colonized by continental European countries, the Type C outlet is predominantly used. Many countries use a mix of different types. For example, China’s standard electrical outlet accommodates Type A, C, and I plugs.

The source of the different outlet types by country:
WorldStandards

Outlet types include:
A, B, C, D, E, F, G, H, I, J, K, L, M, N, O

## Voltage & Frequency

There are essentially two different voltages used throughout the world. The voltage in most countries is between 220 and 240 volts. However, North America, Japan, and a few other countries have a voltage between 100 and 127 volts. This highly correlates with the countries that use Type A, B outlets. Frequency also varies between countries but it is less consequential than voltage, since most electronic equipment is compatible with both. Most of the time, countries with a voltage between 220 and 240 volts use 50 hz, while countries with a voltage between 100 and 127 volts use 60 hz. However, there are some exceptions. For example, South Korea, Philippines, Guyana, and Peru all use 60hz frequency, despite have a voltage between 220 and 240 volts. However, there may be some variations within countries depending on the region or the specific electrical system being used.

The source of the different voltages and frequencies by country:
WorldStandards

Voltages and frequency categories:
100-127 volts, 220-240 volts, 50 hz, 60 hz

## Synchronous Grid

Many countries have connected their electrical grids together. This helps save energy and makes the grid more resilient to blackouts. Most of continental Europe is connected except for Scandinavia. Due to being one country for many years, most of the power grids of the former USSR countries are interconnected. There are many other locations were multiple countries have pooled their resources to create a synchronous grid between them. Not all countries are part of synchronous grids, and there may be variations in the level of interconnectivity between grids.

The primary source of the data:
Wikipedia