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.
This is no coincidence, as the hybrid version of the type O socket was designed to accommodate types A, B, C, and O plugs. There is no standard type O socket, as it has not been produced.
A hybrid version socket accommodates types A, B, C, and O plugs. Since Thailand runs on 230 Volts mains, newer versions of the hybrid sockets most likely would be incompatible with American plugs.
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.
However, the type O plug is compatible with the type E and F socket, though it’s very unsafe.
The lack of safety on the compatibility made the Thailand government ban the sake of appliances with type E and F connections in Thailand in 2008.
When the type E or F plug is used with the type O hybrid sockets, it’ll be ungrounded, and when plugged partially, part of its pins would be exposed, thus the risk of electrocution.
Though the government has banned the sale of appliances with type E and F connections, most Thailand residents own appliances with type E and F connections.
As a result, a special plug adapter was invented. It ensures the type E and F plugs are grounded when connected with a hybrid Thai outlet.
Thinking about the reasons that prompted the Thai government to create a new electric standard instead of adopting existing alternatives is perplexing.
Standardizing a plug like a type F plug would have been a better move, as it’s compatible with type C, E, and F sockets, which are widely used in the country.
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.