Abstract: The present invention concerns an apparatus and a method for detecting a fire, which apparatus includes at least one alarm signalling device and at least one detecting unit, and wherein the apparatus interacts with a switchboard. The invention is designed to achieve early warning when abnormal condition occurs in a switchboard, and where an alarm unit can be detached without access to the switchboard power supply. This can be achieved if the apparatus is located in a recess in the cover where the apparatus is connected to the switchboard with at least one connector, and where the connector at least provides power to the apparatus. Hereby it is achieved that the Fire alarm apparatus can be directly removed from the switchboard front without in any way interfering with the electrical installation. Especially when the apparatus is supplied with low voltage through the connector, it will be easy to remove and possibly replace the fire alarm.