Why can't you mate a 120 V, 100 A Bates plug to a 220 V, 100 A Bates plug?

Why can't you mate a 120 V, 100 A Bates plug to a 220 V, 100 A Bates plug?

• A. The pin spacing is different
• B. The current rating is different
• C. The plug shape is different
• D. The wire gauge is incompatible

Answer: (A)

The key idea is that plugs and receptacles are designed to fit together only if their pin geometry matches. The Bates plug for 120 V uses one pin spacing, while the Bates plug for 220 V uses a different spacing. Because the metal contacts must line up perfectly to mate, a 120 V version cannot physically connect to a 220 V version if their pin spacings are different. This keying by spacing prevents dangerous cross-connection of a higher voltage into a lower-voltage circuit. The current rating being the same doesn’t change this physical incompatibility, and wire gauge isn’t the issue here—it's the exact arrangement of the pins that stops the connection.

The key idea is that plugs and receptacles are designed to fit together only if their pin geometry matches. The Bates plug for 120 V uses one pin spacing, while the Bates plug for 220 V uses a different spacing. Because the metal contacts must line up perfectly to mate, a 120 V version cannot physically connect to a 220 V version if their pin spacings are different. This keying by spacing prevents dangerous cross-connection of a higher voltage into a lower-voltage circuit. The current rating being the same doesn’t change this physical incompatibility, and wire gauge isn’t the issue here—it's the exact arrangement of the pins that stops the connection.