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Wire & Cable Size Calculator

Select the correct cable cross-section (mm2) for any electrical load - based on IS 694 current-carrying capacity tables with installation method derating.

Load Details
Full Load Current
amperes
Design Current (x1.25)
amperes
Recommended Cable Size
mm2
IS 694 Capacity Table -
Size (mm2)Base Capacity (A)Derated Capacity (A)Status

Derating factor applied for selected installation method. Add further derating for cable grouping and ambient temperature above 30°C.

Enter load details on the left to get cable size recommendation.

Calculate full load current (I = P/V for single phase, P/(1.732 x V x PF) for three phase). Select a cable whose derated capacity is at least 125% of full load current. Also check voltage drop - IS 732 allows max 2.5% from service entrance to final outlet.

2.5 mm2 copper PVC cable carries approximately 20A clipped direct, 16A in conduit. Aluminium same size carries about 15A clipped direct. Always apply derating for grouping, high temperature and installation method before finalising cable size.

Aluminium needs roughly 1.5x cross-section of copper to carry the same current but is lighter and cheaper. Commonly used for service entrance, mains feeders and distribution above 16 mm2. For final circuits and sockets, copper is preferred for connection reliability.