Class A Fire Alarm Wiring

Fire Alarms

• In a large home, a single smoke detector isn’t enough. Instead, you need several in place to protect your family. For truly rambling estates, your detectors should be wired together in a system that alerts both you and your security provider that there is a problem. This system may include alarms that you pull to notify everyone in the building that there is a problem. When putting in a system such as this, you need to choose a wiring style. Class A is one option.

Class A

• In Class A fire alarm wiring, the system's circuit runs in a loop from the main panel to each device, then back to the panel. All the detectors are linked, but each one is also directly linked to the main control. This differs from Class B wiring, in which the circuit runs in a straight line from the main panel to the first device, then to the second, then the next, and so on, until it terminates in an end panel.

Advantages

• Installing Class A fire alarm wiring offers advantages over other styles. In Class A wiring, a malfunction in one device won’t affect the others; you'll see a warning light on the main control panel for the problem smoke detector and can immediately act to fix it. A malfunction in a Class B loop sets off the entire system with no way to remotely determine where the issue is. You must check each device individually until you locate the source of the malfunction. The Class A system also tells you where smoke is being detected, allowing you to react to the problem more quickly.

Considerations

• Class A fire alarm wiring is slightly more complicated to install, since you must link each detector or alert center back to the main panel. It's easier to read, maintain and repair, so the initial increased effort ends up being worth it once the system is active. Depending on the fire alarm system you're installing, a Class A set up could be described as Style D, Style Z, or Style 6 or 7.