For those who travel abroad frequently, it’s common to notice that some countries have sockets marked with 110V, unlike the 220V sockets in China. This raises the question: do voltage differences exist between countries, and why are they not standardized?

Due to varying electrical environments worldwide, the voltage used for residential power differs, affecting the compatibility of electrical appliances.

Here’s a quick look at the voltage used in different countries:

Understanding this, you might feel relieved that many countries use 220V.

But why doesn't China follow the U.S. example and use 110V?

A common thought is that lower voltage is safer. However, the answer is more complex.

In 1879, Thomas Edison created an effective carbon filament light bulb that operated well at 110V. He believed this voltage was safe and economical for distribution.

Later, a different voltage level—220V—was also recommended. After a heated debate between Edison and Nikola Tesla on the merits of direct current versus alternating current, the U.S. gradually adopted 110V for its power supply.

While the U.S. encountered various voltage types during its power system development, 110V eventually prevailed.

With advancements in technology, both 110V and 220V are now functionally similar for most appliances.

So, why didn’t China adopt 110V?

When the U.S. adopted 110V, European countries found it too low, resulting in significant losses during transmission. They promoted 220V, which became the standard for most countries.

Given China's historical context of low productivity and economic constraints, choosing 220V helped minimize losses and reduce the consumption of copper and other metals. In 1901, Shanghai began using 200V for public power supply, and in 1930, China established 220V as its standard voltage.

Regarding safety, while lower voltages can be safer, both 110V and 220V exceed the safety threshold. The danger from electric shock is more dependent on the current flowing through the body and the environment.

For appliances, using devices designed for one voltage in another voltage environment can lead to issues. Appliances that operate within a certain voltage range can usually function safely, but expensive devices with strict voltage requirements should use a transformer when used abroad.

If you take a 220V appliance to a 110V country, it may not work properly, if at all. However, many international brands now design appliances to accommodate a range of voltages, from 110V to 240V.

If you travel often, it's advisable to carry travel adapters and converters.