Honeywell Silent Knight SK318PT Installation And Operation Manual page 95

Figure 7.1 and Figure 7.2 show how wire length is determined for out & back tap and T-Tap.
Figure 7.1 Calculating wire run length for a simple out and back
When using T-taps, the total length of all taps and the main bus must not exceed 40,000 feet. This requirement must be met in addition to
the maximum distance requirements for the various wire gauges.
Figure 7.2 Calculating Wire Run Length for a T-Tap
6820 / 6820EVS Manual P/N LS10144-001SK-E:C 09/28/2017 91