Cable voltage drop estimator: Checking conductor length in voltage drop — Worked Guide

What are you checking when checking conductor length in voltage drop?

Estimate voltage loss on copper or aluminum cable routes for DC, single-phase AC or balanced three-phase AC loads. Enter your actual one-way distance, conductor size, current, power factor and conditions. Results show estimated volts, percentage and comparison to a limit entered by you.

Start with the practical question: checking conductor length in voltage drop. Identify which values are given, which are assumptions and what the calculated output actually describes. The tool's guidance below sets the scope; it is not an independent certification or legal decision.

Which inputs should you prepare first?

Choose DC, single-phase or balanced three-phase and conductor material. Input supply voltage, load current, one-way cable length and conductor cross-sectional area in square millimetres. Set estimated conductor temperature, power factor and reactance (Ω/km). DC ignores power factor and reactance. The calculation uses an approximate 20°C resistivity with a linear temperature adjustment.

DC uses 2×I×L×R, single phase uses 2×I×L×(R cosφ+X sinφ) and three-phase uses √3×I×L×(R cosφ+X sinφ), with L in kilometres. The target percent is an assumption you provide, not a statutory compliance limit. Cable construction, installation conditions, load distribution and manufacturer resistance data must be reviewed before design decisions.

For a reproducible trial, the worked example uses: 24 V DC, 10 A, 100 m one-way copper, 10 mm² at 20°C. Enter the same values first, then change one parameter at a time to see what changes.

• Choose DC, single-phase or balanced three-phase and conductor material. Input supply voltage, load current, one-way cable length and conductor cross-sectional area in square millimetres.
• Set estimated conductor temperature, power factor and reactance (Ω/km). DC ignores power factor and reactance. The calculation uses an approximate 20°C resistivity with a linear temperature adjustment.

Worked example: inputs and displayed result

Example inputs: 24 V DC, 10 A, 100 m one-way copper, 10 mm² at 20°C.

Example result: Approximately 3.45 V drop or 14.37%. The DC formula counts the outgoing and return cable paths (2 × I × L × R).

The example uses the published calculator's own input assumptions. The displayed result is conditional on those exact settings; changing units, dates or other fields can change it.

How to interpret the result and its limits

Do not turn the calculator output into a purchasing, engineering or financial decision without checking the actual conditions.

The calculated result is a model for the specified inputs. Confirm physical measurements, time periods, included charges or other conditions relevant to the problem.

A final verification checklist

Before relying on the result, confirm the input values and the meaning of every displayed unit. For checking conductor length in voltage drop, it is especially important to retain the exact context in the worked example rather than carrying the number into a different scenario.

Re-run the calculation with your real measurements or verified amounts and compare the result with the applicable source document, manufacturer's information or official rules where these matter. The calculator explains an estimate, not approval of an installation, contract or entitlement.

• Check units, dates and input definitions
• Reproduce the example before entering real values
• Read the stated limits and independently verify any regulated or safety-critical application