Aspects of the present disclosure provide systems, methods, and computer-readable medium for zone isolation by a fire detection system. In particular, a fire detection and alarm system may typically use either a voltage-sensing isolator which monitors voltage on a system line and isolates one or more zones of a building based on the voltage, or a current-sensing isolator which monitors current on a system line and isolates a building zone based on the current. However, these types of simple short-circuit isolators fail to accurately and quickly distinguish between different fault scenarios. In other words, these types of isolators are unable to distinguish false positives or false negatives due to changes to characteristics on a system line. For example, system lines not only carry voltage and current for detection and alert devices on the system line but may also carry communications between the devices. Accordingly, determining to isolate a zone solely based on the voltage or solely based on the current does not allow a detection and alarm system to distinguish between actual short circuits and false short circuits.

Aspects of the present disclosure may overcome the above-described limitations of simple short-circuit isolators by using multiple data sources in order to pinpoint correct and incorrect boundaries in the functioning of a detection and alarm system. In an example, an isolation circuit is described which uses a combination of current and voltage on a system line to determine an impedance of the system line and determine whether to isolate a building zone based on the impedance. An example of the isolation circuit and components of the isolation circuit used to make decisions corresponding to isolation based on merged data instead of relying on individual parameters are also disclosed herein.