Voltage Drop Calculator
Verify terminal voltage meets device operating requirements
Parameters
W
m
Formula
Drop = 2 × Length(m) × Current(A) × Resistivity(0.0175 Ω·mm²/m) ÷ Cross-section(mm²)Engineering Tips
- Terminal voltage should not drop below 85% of rated voltage for security devices.
- Copper resistivity ρ = 0.0175 Ω·mm²/m at 20°C; resistance increases at higher temperatures.
- Account for connector contact resistance — add 5% extra margin in practice.
- For runs over 100m, strongly consider POE or 24V/48V power solutions.
Results
3.3V / 12V
Critical — Drop over 15%, must revise the design
Load Current5.00 A
Voltage Drop8.75 V
Drop Percentage72.9%
Terminal Voltage3.3 V
Suggestions
- Upgrade to thicker cable (current 2×1.0mm² (AWG 17), recommend 2×1.5mm² (AWG 15))
- Switch to a higher voltage supply (e.g. 24V or 48V) to significantly reduce drop
Based on your power and distance requirements, we recommend:
Standard Switching Power Supply 48W-120W
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