These are ½ Amp poly fuses (small yellow discs that look similar to some capacitors) that acts like a circuit breaker on the 5 Volt supply to the PCB from the regulator. F1 installs very near the DB9, in the middle of some of the capacitors you have already installed. F2 installs ...
to then feed by smaller gauge wires into each breaker of the system by tapping off from the main branch circuit. With both block diagram arrangements, the main shutoff switch112can be actuated by a responding fireman in an emergency to shut off all power into the building and to its multip...