V
Please enter all required numeric values.
RESULTS
Input Parameters Specification
Source VoltageSelect the system voltage used for voltage drop wire size and cable sizing calculation.
PhaseChoose single phase or three phase for copper and aluminium conductor sizing.
CurrentLoad current in amperes used to estimate required AWG or MCM cable size.
DistanceOne-way cable run distance in feet for electrical wiring voltage drop design.
Voltage DropSelect 3%, 5%, or enter a custom voltage drop value in volts.
Material OutputShows recommended copper and aluminium wire-cable sizes using original AWG/MCM lookup logic.
Practical Operational Examples
House Wiring Cable Size
Estimate copper cable size for lighting, motor, pump, inverter, and electrical panel wiring runs.
Aluminium Feeder Cable
Compare aluminium wire size against copper wire size for long-distance voltage drop control.
Diagrams & Theory
Copper and aluminium conductors have different resistance constants. For the same current, distance, voltage and voltage drop limit, aluminium generally needs a larger cable size than copper.
Formulas & Mathematical Logic
Step 1: Read source voltage V, phase multiplier P, current A, distance D, and voltage drop limit.
Step 2: If voltage drop is 3% or 5%, use that decimal value. If custom is selected, use custom voltage drop divided by source voltage.
Step 3: Circular mil area CM = (K × 2 × A × Distance ÷ (Source Voltage × Voltage Drop)) × Phase Multiplier.
Step 4: Copper uses K = 11.2. Aluminium uses K = 17.4. The calculator then compares CM and ampacity against the original AWG/MCM table.
Step-by-Step Example
Example: source voltage = 240 V, phase = single, current = 30 A, distance = 100 ft, voltage drop = 3%.
Voltage drop ratio = 0.03. The calculator applies the same run length, current and phase value for both conductor materials.
Copper is checked using K = 11.2 and copper ampacity table values.
Aluminium is checked using K = 17.4 and aluminium ampacity table values.
The final result displays the nearest AWG or MCM size that satisfies the original lookup conditions.
How to Use This Calculator
Select the source voltage used by the wiring system.
Choose single phase or three phase.
Enter the load current in amperes.
Enter one-way cable distance in feet.
Select 3%, 5%, or custom voltage drop.
Click Calculate to get copper and aluminium cable size results.
About This Calculator
Estimate copper and aluminium cable size from voltage drop.
The CalcBoy Copper and Aluminium Wire Cable Size Calculator helps compare conductor size for electrical wiring runs using voltage, phase, current, distance, and voltage drop limit.
Long wire runs lose voltage because every conductor has resistance. When current flows through the cable, some voltage is dropped along the wire before it reaches the load. If the wire is too small, motors may start poorly, lights may dim, inverters may show low-voltage behavior, and equipment may run hotter than expected. Cable sizing by voltage drop is therefore useful for feeders, pump wiring, subpanels, long lighting runs, workshop circuits, solar/inverter wiring, and many field installation checks.
Copper and aluminium are not the same electrically. Copper has lower resistance, so it usually reaches the target voltage drop with a smaller conductor size. Aluminium is lighter and often cheaper for feeder runs, but it normally needs a larger AWG or MCM size for the same current and distance. This calculator keeps both outputs side by side so you can quickly compare material options during planning.
Best UseVoltage drop based wire sizing for copper and aluminium conductors.
Useful ForPanels, pumps, motors, inverter lines, lighting runs and long feeders.
Design TipLong distance and high current both push the required cable size upward.
Safety ReminderAlways confirm final cable size with local electrical code and installation conditions.
Tip: Voltage drop sizing is only one part of cable selection. Final wiring must also consider breaker rating, insulation temperature, installation method, conduit fill, ambient temperature, grounding and local electrical rules.
Frequently Asked Questions
What does this wire cable size calculator do?
It estimates copper and aluminium cable size based on voltage, phase, current, distance, and voltage drop limit.
Why is aluminium cable usually larger than copper?
Aluminium has higher resistance than copper, so it often needs a larger conductor size to carry the same current with the same voltage drop limit.
What is a good voltage drop limit?
Common planning limits are 3% for stricter voltage control and 5% for less sensitive circuits, but local code and equipment requirements should be checked.
Is distance one-way or round-trip?
This calculator uses the entered distance with the original voltage-drop formula logic. Enter the same distance convention used by your installation method or calculator reference.
Can I use this for three phase wiring?
Yes. Select Three in the phase option to apply the three-phase multiplier used by the source calculation.
Is this enough for final electrical installation?
No. It is a planning calculator. A licensed electrician or local electrical code should be used for final conductor selection and protection sizing.
What does AWG and MCM mean?
AWG is American Wire Gauge for smaller conductors, while MCM/kcmil is used for larger cable sizes.
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