The IFU100 is a customizable enclosure designed to accommodate input/output interface modules, relays, power supply units and chargers to function as an interfacing device to link independent fire alarm networks and security mechanisms with the centralized fire alarm and detection and PAVA systems in a building. The interface devices and power supply are housed in the steel enclosure which provides IP30 protection. The enclosure has a key lock mechanism to restrict unauthorized access. The IFU100 is an easy-to-install unit that can interface addressable fire alarm networks with conventional fire alarm networks and building management systems such as HVAC, lifts, security and power systems.