The present disclosure discloses an expandable wireless control system for and a method of managing and controlling building automation, lighting system, security system and electrical appliances. This system, based on a concept of modular mailboxes intercommunicating wirelessly by radio frequency and infrared frequency, can be used in new homes and buildings or easily retrofitted into existing homes and buildings without any need for massive rewiring, comprises of: microprocessor control switch panel, handheld remote devices, user input interface device, wireless multipurpose transceiver unit (MPU, 300) that interpose with remotely controllable subsystem of third party devices and electrical appliances to enable control of these devices to become a part of said system, and a wireless multipurpose transceiver with communication interface (MPUCOM, 302) in combination with a graphical user interface software that turns a personal computer into a setup computer, command centre, remote management gateway that connects to internet and telecommunication network (702).