Type A vs Type O Plugs: Grounding & Voltage Differences & Compatibility
Type A is a 2-pin, ungrounded plug rated 15A at 100-127V, while Type O is a 3-pin, grounded plug rated 16A at 220-240V. The two differ mainly in grounding, voltage, amperage and pin design, which is what decides compatibility — whether a Type A plug fits a Type O socket, and vice versa. Next, check type H vs type M plug.
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Type A
|
Type O
|
|
|---|---|---|
| Standard | NEMA 1-15 | TIS 166-2549 |
| Pin Configuration | Two flat parallel pins (15.9mm apart, 15.9mm long, 6.3mm wide) | Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin) |
| Grounding | Ungrounded | Grounded |
| Pin Count | 2 | 3 |
| Amperage | 15A | 16A |
| Voltage Range | 100-127V | 220-240V |
Key Differences Between Type A and Type O
Here's how Type A and Type O compare, point by point.
- Grounding: Type A has no grounding. Type O adds a grounding pin or clips to protect against electrical faults.
- Pin Size and Shape: Type A: Two flat parallel pins (15.9mm apart, 15.9mm long, 6.3mm wide). Type O: Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin).
- Application: Type A is typically used for heavy-duty appliances such as hair dryers, kettles, and heaters. Type O is typically used for heavy-duty appliances such as hair dryers, kettles, and heaters.
Type A and Type O Compatibility
Type A in Type O Sockets: Generally no. A Type A plug (Two flat parallel pins (15.9mm apart, 15.9mm long, 6.3mm wide)) does not fit a Type O socket (Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin)) without a travel adapter. Next, check type E vs type I plug.
Type O in Type A Sockets: Generally no. A Type O plug (Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin)) does not fit a Type A socket (Two flat parallel pins (15.9mm apart, 15.9mm long, 6.3mm wide)) without a travel adapter.
If you're planning a trip, tell us which country you're visiting and we can confirm whether you need a Type A or Type O travel adapter.
Does a Type A plug fit into a Type O socket?
Generally no. A Type A plug (Two flat parallel pins (15.9mm apart, 15.9mm long, 6.3mm wide)) does not fit a Type O socket (Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin)) without a travel adapter.
Are Type A and Type O plugs the same?
No. Type A follows the NEMA 1-15 standard and Type O follows TIS 166-2549 — they differ in grounding, pin count, voltage rating.
Which countries use Type A and Type O plugs?
Type A plugs are used in 61 countries, including American Samoa, Anguilla, Antigua and Barbuda, Aruba, Bahamas. Type O plugs are used in 1 countries, including Thailand. 1 countries use both, including Thailand. Also see is type A compatible with type C.
How can you tell a Type A plug from a Type O plug?
A Type A plug has two flat parallel pins (15.9mm apart, 15.9mm long, 6.3mm wide), and is ungrounded. A Type O plug has three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin), and is grounded. The quickest tell is the grounding pin or clips — only the grounded one has them.