Cable Voltage Drop Calculator
Accurately calculate voltage drop, power loss and remaining voltage for DC and AC cable installations. Supports copper and aluminum conductors with temperature correction.
Input Parameters
How is Voltage Drop Calculated?
Voltage drop is calculated using Ohm's Law and the conductor's resistance. The formula takes into account the total circuit length (round-trip), load current, and conductor resistance per unit length:
- V_drop = 2 × I × L × R / 1000, where I is current in amps, L is one-way cable length in meters, and R is resistance in Ω/km
- The factor of 2 accounts for the round-trip path (current flows out and back)
- Conductor resistance increases with temperature — copper rises approximately 0.393% per °C above 20°C
- For aluminum conductors, resistance is approximately 61% higher than copper for the same gauge
This calculator also applies to single-phase AC circuits where power factor is close to 1. For three-phase systems, divide the result by √3.
Frequently Asked Questions
What is voltage drop and why is it important?
Voltage drop is the reduction in voltage caused by resistance in a cable conductor. Excessive voltage drop can cause equipment malfunction, reduced efficiency, and overheating. Most standards recommend keeping voltage drop below 3%.
How does temperature affect voltage drop?
As temperature increases, conductor resistance increases. Copper resistance rises by approximately 0.393% per ℃. Higher ambient temperatures result in higher voltage drop for the same current.
What is the difference between copper and aluminum cables?
Aluminum has about 61% of the conductivity of copper but is lighter and less expensive. For the same current capacity, an aluminum cable needs to be about 1-2 AWG sizes larger than copper.
How do I reduce voltage drop in my installation?
To reduce voltage drop: use a larger wire gauge, reduce cable length, use copper instead of aluminum, or increase the system voltage. Proper sizing based on actual load current is essential.
Need Custom Cable Assemblies?
We provide custom cable assemblies with various gauges, materials, and connectors to meet your specific voltage drop and current requirements.
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