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Voltage Drop Check
Voltage drop and % for a chosen cable size.
ElectricalCore inputs only — quick sizing with engineering defaults.
Inputs (SI units)
Results
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Engineering Formula
- DC / 1-φ: V_d = 2 × ρ × L × I / A
- 3-φ: V_d = √3 × ρ × L × I / A
- % drop = V_d / V × 100
Drop is IR loss on the loop. For balanced 3-φ systems only line-to-neutral drop matters — hence the √3 factor.
Step-by-step Calculation
- 1.Factor
22 - 2.Drop
k·ρ·L·I / A4.3 V
Design Assumptions
- • Resistive drop only; reactance ignored (short LV cables).
- • 20 °C reference — use DC Cable Sizing for temp correction.
Engineering Tips
- ◆Lighting circuits: ≤ 3%.
- ◆Power circuits: ≤ 5% total from source (per NEC 210.19).
Warnings
- ▲Drop > 5% causes motor heating and PV clipping.
Standards & References
IEC 60364-5-52IS 3043NEC 210.19
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