Voltage Drop

Single-phase or three-phase voltage drop over length.

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Formula and source

VD = 2 * I * R * L for single-phase; VD = √3 * I * R * L for three-phase. R from NEC Chapter 9 Table 8 (DC ohm/kFT) with temperature correction; reactance per IEEE 141 for long runs.

NEC 2023 (NFPA 70). Chapter 9 Tables 8 and 9; IEEE 141 by name.

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