A necessary note. Wire resistance is from NEC Chapter 9 Table 8 — the same table this suite's NAC voltage drop calculator uses. Sums the total wattage tapped on the circuit into a single equivalent load resistance (line voltage² ÷ tapped watts) at the full run distance — a conservative field check, not a tap-by-tap segment calculation. End-of-line voltage comes from the voltage-divider relationship between that load resistance and the wire resistance — not from assuming full nominal current keeps flowing as voltage sags, since a fixed-impedance tap draws less current at a lower voltage. dB loss is 20 × log₁₀(end voltage ÷ line voltage), standard for constant-voltage audio distribution. This tool is a planning aid, not a substitute for a code review by a licensed design professional or your authority having jurisdiction.