Many people are under the impression that when they walk into a building, all the systems have been tested to function correctly in the event of a fire or emergency. Individually, this is true. However, many fire protection and life safety systems are designed to work together and the interconnection (i.e. handshake) between the systems was not required to be tested until NFPA 4, Standard for Integrated Fire Protection and Life Safety System Testing, was published in 2015. This Campus Fire article explains the importance of closing this gap and provides a simple example of how integrated system testing is critical to ensure fire protection and life safety systems operate when the seconds count.