In Thailand, the optimal voltage is 220 V, and a frequency of 50 Hz. You can make use of your electric appliances in Thailand if the optimal voltage in your country is in between 220 – 240 V (as is in Australia, Europe, UK, and most of Asia and Africa). Manufacturers take these variations into account. If the optimal voltage in your country is between 100 V – 127 V (as is in Canada, US, and most South American countries), you have to use a voltage converter in Thailand. You can also use a combined power plug (ปลั๊ก ต่อ , which is the term in Thai) adapter/voltage converter.
If the frequency in Thailand (50 Hz) is different from the one in your country, it is not recommended to make use of your appliances. However, if there is no voltage difference, you could (at your own risk) try to use the appliance for a brief time. Be especially careful with moving, rotating, and time-related appliances like electric fan heaters, shavers, and clocks.
You can check the label on the appliance to be sure. Some appliances never need a converter. If it is stated on the label- ‘INPUT: 100-240V, 50/60 Hz’ the appliance can be used in all countries, this is common for chargers of tablets/laptops, photo cameras, cell phones, toothbrushes, etc.
In Thailand, the sockets and power plugs are classified to A, B, C, F, and O.
Type A: Used mainly in North and Central America, Japan, and China. It only works with plug A.
Type B: Similar to type A; but with an extra prong for grounding. This socket also works with plug A.
Type C: also called the standard “Euro” plug. It also works with plug E and plug F.
Type F: also called “Schuko.” It also works with plug C and plug E.
Type O: It is unique to Thailand, but it also works with plug C, plug E, and plug F.