Preliminary cable sizing with your own engineering data

Cable area is not selected by current alone

A conductor must carry the intended load under its installation conditions, keep voltage drop within the chosen design target and meet any applicable fault and protection requirements. The smallest candidate that passes one check can fail another.

The ElectricalDyev tool therefore does not contain a hidden standards table. You enter or import the candidate data that you are authorised to use. Every result that depends on those values remains labelled for review.

Start with design current

Design current should describe the circuit load after the relevant demand assumptions have been applied. It is not automatically the connected nameplate total, and it is not the breaker rating. If the load has starting or cyclic behavior, a single steady-state current may not describe the full design case.

Next, enter base ampacity for each candidate from a traceable source. Correction factors are multiplied to obtain corrected capacity. For example, a base ampacity of 40 A with factors 0.90 and 0.85 produces 40 × 0.90 × 0.85 = 30.6 A.

Compare every enabled constraint

The tool sorts candidates by cross-sectional area and reports why each candidate passes or fails. A cable can have adequate corrected ampacity but exceed the selected voltage-drop target. An optional thermal requirement can also exclude a candidate even when its steady-state result looks acceptable.

This ordering is useful because it exposes the governing constraint. It does not mean the first passing result is automatically suitable for procurement.

Data quality matters

Record conductor material, temperature basis, installation arrangement, grouping and the source of any impedance or correction value. Mixing values from unrelated products or conditions makes the calculation impossible to audit.

The final review should also consider terminals, parallel-conductor arrangements, protective-device operation, fault level, fire performance, mechanical protection and the rules that apply to the actual location. Cable sizing is a design workflow, not a single arithmetic answer.