Relay B rules: Common and Normally Open relay contacts are used to supply a CLOSED circuit to deactivate safety equipment upon a polarity reversal signal from the FACP upon alarm conditions. This ...

When it comes to electronics, it seems like a relay is such a simple device – yet, it is able to interface some pretty elaborate high-end systems with a fire alarm system.

I have no idea if the circuits or systems are separate. I believe everything is wired back to a single point though as they were shutting off my units while hooking up the fire alarm and they were ...