Butterfly:

The snap-action mechanism in a switch composed of the spring guide, two switch blades and extension spring: a double break mechanism.

ANSI:

American National Standard Institute; a standard-setting agency of the United States which approves the design and/or performances of electronic/electrical components distributed in the world market.

Cadmium Oxide:

A compound added to silver to make it more able to resist welding.

Arc:

Gaseous electrical discharge between separated contacts of a switch, involving a stream of electrons, metal vapors and ions.

Capacity:

Usually refers to the current handling capability of a switch.