Method: Conductor resistance is estimated from: R = ρ × L ÷ A with resistance adjusted for conductor temperature. For DC: ΔV = 2 × I × L × R For single-phase AC: ΔV = 2 × I × L × (R cosφ + X sinφ) For balanced three-phase AC: ΔV = √3 × I × L × (R cosφ + X sinφ) where R and X are conductor resistance and reactance per unit length, φ is the load phase angle and cosφ is the power factor. The entered cable length is one-way length. The factor of 2 in DC and single-phase calculations accounts for the outgoing and return conductors. Three-phase conductor power loss is estimated as: P_loss = 3 × I² × R_one-way while single-phase and DC loss is estimated using the resistance of the two-conductor current path. The resistance model uses nominal bulk-material resistivity and therefore provides an engineering estimate rather than a replacement for manufacturer AC-resistance data. Actual cable resistance can also be affected by conductor construction, stranding, skin effect, proximity effect and operating temperature. Cable ampacity, short-circuit withstand and protective-device sizing are separate requirements and are not determined by voltage drop alone.