In order to find this answer，we must know about the following question：
What does interconnected smoke detector mean?
When smart fire alarm detectors are interconnected, each alarm can now tell you where there’s smoke in any room that has a smoke alarm. A traditional smoke alarm can just alert you to the presence of smoke, fire. but it can only detect the area around it. So, smart fire alarm detectors will have a lot of room for development in the future.
ok，let’s deal with the question：How many smart fire alarm detectors can be interconnected?
Interconnected units must meet all of the following requirements:
A maximum of 18 compatible units may be interconnected (maximum of 12 smart fire alarm detectors). It’s a very simple and a very effective system.
The same fuse or circuit breaker must power all interconnected units.
The total length of wire interconnecting the units should be less than 300 meters (1000 feet). This type of wire is commonly available at hardware and electrical Supply stores.
It is worth noting that all wiring must conform to all local electrical codes and your local building code for further connection requirements.
If you are in doubt about any of these requirements, contact an experienced Electrical Professional to complete the installation of these smart fire alarm detectors.