A modular operating switch assembly comprises a housing defining a plurality of switch operating cells. Each of the operating cells has guide walls, a switch actuating member in sliding contact with the guide walls, and a switch contact carrier configured to be selectively equipped with contact pairs such that each of the contact pairs is associated with at least one said switch actuating member. Each switch actuating member is operable to be selectively connected to a key cap associated with a single switch operating cell, or with a key cap associated with a plurality of adjacent switch operating cells.