How Does Conventional Class A Fire Alarm Wiring Work?

Class A wiring in a fire alarm system uses a primary signal path to all the devices, and if the signal path is interrupted, Class A wiring uses the Class A Return wires as an alternate pathway the signals. During fire, if a wire breaks, Class A Wiring provides an alternate route for signals to pass between field devices and the fire alarm panel.

NFPA's 7 Classes of Fire Alarm Paths

The NFPA has divided the signal paths in a fire alarm system into 7 classifications: Class A, Class B, Class C, Class D, Class E, Class N, Class X. These classifications don't show how to wire anything, these classifications show what happens when things go wrong. To start with, as a life-safety system, a fire alarm system detects fire and lets people know about the fire.

What Is a Class

A Class A fire alarm system is more expensive than a Class B system. This is due to the extra installation and heightened redundancy. However, the Class A system is safer, and leaves less to chance with regard to safety and fire prevention. 5 Adaptability

What is the difference between Class A wiring and Class B ...

A class A fire alarm circuit has wires (typically one pair) leaving the fire alarm control panel (FACP), going to the devices on the circuit, and returning to the FACP, terminating on a different set wiring terminals.

What's the Difference Between Conventional Class A and ...

If a connection or wire is broken, Class B Wiring Systems stop working properly. But because the wiring is supervised by the fire alarm panel, however, as soon as the connection is broken, the panel indicates there is trouble. The broken wire can be fixed right away. Class A Wiring Systems go a step further. Not only do they indicate there is trouble in the wiring, but if a fire breaks out in the building, before a single broken wire or connection has been fixed, all devices will still work.

Do Your Systems Have Class and Style? | Electrical ...

In addition to installing fire-alarm circuits in accordance with the NEC, contractors must understand that fire-alarm system wiring has class and style. As it turns out, the NFAC only classifies circuits as A or B. Both provide monitoring for integrity. Class A circuits will continue to operate even with a single break or ground fault.