Why are replacement plugs in the US only rated at 125V even though many of our devices can also be run on 220V?
This is a code issue. By code, certain outlets should only be used on a 120 V circuit. And a different outlet should be used on a 240 V circuit.

If the 120-V outlet were used on a 240-V circuit, somebody could plug in a device that isn't rated for 240-V. This would likely damage the device, and could cause further damage like starting a fire or electrocuting the user.

Your example plug is designed to fit the NEMA 5-15 outlets that are commonly used for 120 VAC, 15 A circuits in North America. Therefore retail vendors describe them as "120 V" plugs.



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