Type O
Plug Types · 5 specs
Direct Answer
Type O is Thailand's standard, introduced in 2006 -- three round pins whose earth-pin offset happens to numerically match Type B's, letting Thailand's real-world hybrid sockets also accept American Type A/B and European Type C plugs. Pure single-standard Type O outlets barely exist in practice.
Source: TIS 166-2549 · Last reviewed Aug 28, 2026
Specs
| Pin Count | 3 round pins, 4.8mm diameter |
| Rated Current | 16 A |
| Rated Voltage | 230 V |
| Grounded | Yes |
| Common Regions | Thailand only |
A Standard Almost Nobody Sells in Pure Form
Type O's official designation, TIS 166-2549, uses the Buddhist Era calendar year (2549 = 2006 CE), not a typo. Its earth pin's offset distance happens to numerically match Type B's dimensions, which is what makes it possible for a single hybrid receptacle shape to accept several different plug types at once.
Almost every socket actually sold and installed in Thailand today is exactly that kind of hybrid -- built to also accept ungrounded American Type A/B (flat pins) and European Type C (round Europlug) plugs alongside true Type O plugs, because importing appliances with foreign plugs has always been common. Sources describe a pure, single-standard Type O outlet as existing "only as a theoretical specification" -- despite superficial resemblance, Type O is not interchangeable with the similarly round-pinned Type H (Israel) or Type K (Denmark).