The electrical outlet and power plug type O are only used in Thailand.
The plug, which is rated 16 amp, is codified TIS 166-2549, which coincides with the Buddhist year’s last digits, 2549, which is 2006 in the Gregorian calendar.
The plug was introduced in 2006. The plug has three pins, two power pins, and one grounding pin. All pins in the type O plug are round.
All pins have the same diameter of 4.8 mm, but different length. The line and neutral pins have a length of 19 mm, with 10 mm insulated sleeves, which prevents electrocution when partially plugged.
The earthed pin length is 21.4 mm. The middle of the imaginary line connecting the power pins and the grounding pins have a center-to-center distance of 11.9 mm, which is the same as the type B plug.
The type O plug looks similar to the Israel standard type H and Danish standard type K plug. Despite the similarity, they are not compatible.
Thinking about the reasons that prompted the Thai government to create a new electric standard instead of adopting existing alternatives is perplexing.
Also, the type F plug is very safe.
Since the type O plug would be incompatible with the type A and B outlets in the near future, it’s surprising to think that the Thai government have not adopted the safe type F plug and introduced a transition period, where hybrid versions of the type B and F receptacles and sockets can be installed.