Electrical switch

A switch device comprising:

• a main module, which comprises,
• a main electronic control circuit,
• one or more direct connections to an electrical system of a building and to equipment or one or more devices to be controlled,
• one or more touch sensors or contacts connected to said main electronic control circuit,
• a main box-shaped body configured to house said main electronic circuit, said one or more connections, and said one or more touch sensors,
• at least one port for a reversible electrical or electronic connection of said main electronic control circuit to a secondary electronic circuit, and
• means for a reversible mechanical connection of a housing element of said secondary electronic circuit;
• and
• an accessory module, which comprises:
• a housing element for said secondary electronic circuit;
• electric or electronic connection means of said secondary electronic circuit with said main electronic circuit of said main module;
• and
• mechanical connection means of said housing element of said accessory module to a housing element of said main module,
• wherein said accessory module is configured to provide additional control functions on the electrical system of the building and the equipment or the one or more devices, and
• wherein connecting said main module to said accessory module enables said main module to expand control on said electrical system and said equipment or said one or more devices using the control functions provided by both said main module and said accessory module.