What is the maximum SLC loop length and device count per loop on the EST4?

The EST4 signaling line circuit (SLC) supports a maximum of 250 addresses per loop, consisting of 125 detectors and 125 modules (Page 11) [1].

While the absolute maximum total loop length is 20,000 feet (6,098 meters) using non-twisted, non-shielded wire (Page 181) [1], the allowable distance for a fully loaded loop is 5,738 feet for 14 AWG, 3,608 feet for 16 AWG, and 2,271 feet for 18 AWG (Page 4) [3].

These distances are limited by a maximum circuit resistance of 100 Ohms and capacitance of 0.5 μF (Page 4) [3].