A switch comprises a housing having fixed switching contacts and a slidable carriage which is movable by a switch-on spring. The switch-on spring can be locked in place. A slide having moving switching contacts is also provided and is movable by a switch-off spring, which can also be locked. The slide having the moving contacts is arranged for sliding movement in the carriage. The springs are consecutively unlocked by a trigger mechanism moving twice in the same direction.

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