Cable Voltage Drop
⚡ Electrical-Electronics · Percent voltage drop check based on line length and cross-section (single-phase / three-phase)
In electrical installations, conductor resistance causes an unavoidable voltage loss along the line. On long runs or with undersized cable cross-sections, this drop can cause devices to operate below their rated voltage, lose efficiency, and overheat.
Regulations typically define two different limits: a stricter limit (3%) for lighting circuits, and a somewhat looser limit (5%) for power/outlet circuits — because voltage fluctuation is more easily noticed by eye in lighting (flicker effect).
Limitation of the resistance-weighted approach: this calculation method is based on the conductor’s ohmic resistance. This is accurate enough for small and medium cross-sections (up to roughly 50 mm²), but for large cross-section cables the line’s inductive reactance must also be accounted for — otherwise the voltage drop may be underestimated.
This tool's calculation logic has been checked against a hand-computed numerical verification test. Test source: src/lib/calc/gdusum.test.ts.
- [6] IEC. IEC} 60364-5-52 — Elektrik Tesisatları: İletken Seçimi ve Montajı. International Electrotechnical Commission. (TODO(oz): güncel baskı yılı doğrulanmalı) ↗
Cable Voltage Drop — EngineersLab calc card
Formula: 1Φ: ΔU = 2ρLI·cosφ/S, 3Φ: ΔU = √3·ρLI·cosφ/S
Sources: [6] IEC} 60364-5-52 — Elektrik Tesisatları: İletken Seçimi ve Montajı
Tool version: 1.0.0 · Date:
Source URL: https://engineerslab.com.tr/en/araclar/gdusum
Results are for educational and preliminary-sizing purposes; final engineering design decisions must reference the relevant standards and a licensed engineer's approval.