TECHNICAL CALCULATOR

Cable Size Calculator

Estimate suitable cable size based on load current, phase type, voltage, cable length, material and allowable voltage drop.

Electrical Design Estimator

Estimate Cable Size And Voltage Drop

Load ValueLoad UnitPhase TypeSystem VoltageAuto-sets to 400V for three phase and 230V for single phase.Power FactorUsed only when converting kW to amps. It is not applied to the simplified voltage drop calculation.Cable Length in MetresCable TypeUses SWA-style published values for multicore copper cable. Final design must be checked against the selected cable datasheet and installation method.Maximum Voltage Drop

Cable Installation Derating FactorThis factor accounts for installation conditions that may reduce a cable's current-carrying capacity, including cable grouping, elevated ambient temperature, thermal insulation and enclosed installation methods. Use 1.0 where no derating is being applied. Reduce the factor only where required by the applicable installation conditions, cable-manufacturer data and SANS 10142.1.0 — No derating applied0.9 — Mild derating0.8 — Moderate derating0.7 — Significant deratingThese values are general planning guidance only. Final derating must be verified for the actual installation.

Recommended Cable

10 mm² Copper

Recommended Earth Conductor

10mm²

Cable size is selected based on both current-carrying capacity and estimated voltage drop. This is an estimation and must be verified against SANS 10142 and installation conditions.

Voltage drop is estimated using standard published cable voltage drop values. Final cable sizing should always be verified against SANS 10142, installation method, ambient temperature and actual site conditions.

Load Current: 50,00 A
Required Cable Current after deratingThe calculated load current adjusted by the selected installation derating factor.: 50,00 A
Recommended Cable Size: 10 mm² Copper
Recommended Earth Conductor: 10mm²
Cable Type: PVC/SWA/PVC Multicore 70°C
Cable Material: Copper
Estimated Voltage Drop: 3,15 V
Estimated Voltage Drop %: 0,79%
Maximum Allowable Voltage Drop: 5,00%
Cable Ampacity: 58 A
Published Value Used: 2,10 mV/A/m
Voltage Drop Status: ✓ PASS

This calculator provides a technical estimate only. Final cable sizing must be confirmed by a qualified electrician or engineer in accordance with SANS 10142-1, installation conditions, cable grouping, ambient temperature, fault levels and applicable regulations.

Technical Note

Cable size must be coordinated with the calculated load, selected protective device, installation conditions and allowable voltage drop. Where future expansion is expected, the designer may allow spare capacity, provided the cable, breaker, fault rating and installation remain correctly coordinated and compliant.

Advanced OptionsNot active yet

Advanced technical options coming soon.

Installation Method
Ambient Temperature
Cable Grouping
Buried / Tray / Conduit
XLPE / PVC
Harmonic Loading
Protective Device Type

Technical Notes

Cable Sizing Considerations

Cable sizing must be verified against SANS 10142, installation method, grouping, ambient temperature and protection requirements.

Voltage drop depends on route length, conductor material, load current and power factor.

Protective device selection must coordinate with cable rating and fault level.

Final cable sizing should be confirmed by a qualified electrical designer or electrician.

ELECTRICAL DESIGN SUPPORT

Need Help With Cable Sizing Or Electrical Design?

Emerald can assess your load requirements, cable routes, DB locations, protection requirements and installation conditions to design safe and compliant electrical infrastructure.

Book Site Assessment View Electrical Infrastructure