Engineering calculator

Cable and fuse sizing

Estimate the minimum copper cable cross-section and fuse class for a DC circuit using current, round-trip length, voltage-drop target and cable ampacity.

Circuit typeSystem voltageDesign current (A)Cable length, one way (m)Maximum voltage dropCable ampacity (A)Existing fuse rating (A)Continuous-load factor

Circuit estimate

Recommended cable

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Voltage drop

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Minimum ampacity

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Fuse class guide

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Checks: —

Safety note: Use the larger result from voltage drop and ampacity. The fuse must protect the installed cable and follow the equipment manufacturer’s maximum fuse rating.

Safety and limitations

This tool provides planning estimates only. It is not a substitute for a qualified design, inspection or local code compliance.
Use the exact manufacturer documentation for the equipment, materials, limits and installation method you intend to use. Do not select hardware from the result alone.
Verify every input, unit, operating condition, environmental limit and installation derating before relying on the result.
Protection devices, emergency controls and final commissioning must follow the manufacturer’s instructions and applicable local standards.
Electrical, gas, fuel, towing, structural and fire-safety work must be reviewed or completed by a suitably qualified professional where required.
This result does not include local approval, exact product compatibility, site-specific conditions, fault studies or commissioning measurements.

If any input is unknown, stop and obtain the datasheet or professional verification before purchasing or wiring components.

Results are planning estimates, not a substitute for a qualified electrical design or the manufacturer’s installation instructions.