A fire alarm system should be designed to provide early detection and warning of a fire. The designer must consider the size, complexity and use of the building, and the degree of detection and warning desired. While the design of fire alarm systems is normally regulated by building codes, the level of protection specified is usually a minimum and the designer should consider providing higher levels of protection where circumstances indicate the need. Before looking at the details of the alarm system, it is necessary to understand some of the concepts that are used to assist the system designer. Buildings are divided up into sections in three ways as far as fire safety engineering is concerned: fire compartments, detection zones and alarm zones.