Electrical Schematic Editor — Ladder Diagrams, Cable Sizing & BOM (IEC 60617 / IEC 60364)

Every component placed on a sheet is drawn from the editor's IEC 60617 symbol library — IEC 60617 being the international standard for symbols used in electrotechnical diagrams. Each sheet carries a numbered ladder rail down its left edge to support the usual left-to-right rung convention; the rail is a drawing aid and the editor does not constrain where you place a symbol. The multi-sheet model lets a motor power circuit live on Sheet 1 while the associated PLC I/O rungs sit on Sheet 2, and every CSV export covers the whole document rather than the sheet on screen (image and PDF exports capture the sheet you are looking at). Components are tagged automatically from a per-prefix counter that scans every sheet, so auto-generated tags continue across the document rather than restarting; the tag is yours to overwrite, and a tag you type yourself re-syncs the counter but is not otherwise checked for uniqueness.

IEC 60364-5-52 tabulates the sustained current-carrying capacity (ampacity) of cables by conductor cross-sectional area, insulation type (XLPE or PVC) and conductor material (copper or aluminium). The sizing engine scans a SIMPLIFIED baseline table — 1.5 mm² to 95 mm² — to find the smallest CSA whose rated ampacity meets or exceeds the design load current. For aluminium conductors the copper ampacity is multiplied by a flat factor of 0.78 and floored, never rounded up. That factor is the tool's own simplification rather than a value read from the standard; it is at least the right order — for equal geometry and permitted temperature rise the current scales as 1/√ρ, which for these two resistivities gives ≈ 0.79 — but it is applied uniformly to every cross-section, which the standard's tables do not do.

This is an ESTIMATE, and the panel says so on screen and in its PDF report. The table applies no reference/installation method, no ambient-temperature correction, no grouping factor, and no distinction between two and three loaded conductors, and the tool does not check coordination with the protective device — all of which the standard requires and all of which can move the permissible current substantially. Verify against IEC 60364-5-52 itself and your installation conditions before use.

When the load current exceeds the largest entry in the applicable table — the 95 mm² conductor — the result is flagged OVERLOADED rather than PASS, whatever the voltage drop, and the minimum number of parallel conductors is calculated. Parallel conductors carry equal current when they are the same length, CSA, insulation type and routing (IEC 60364-5-52 §523.2), so the required parallel count is ⌈I_load / I_max⌉. The verdict fails on either condition: an overloaded conductor is never a PASS.

After the CSA is selected on an ampacity basis, the engine checks that the resistive voltage drop along the cable run stays within 3 % of the nominal supply voltage. The drop is computed from the conductor resistivity, the CSA, the one-way cable length and the load current, with an additional √3 factor for three-phase circuits. Both the percentage and the pass/fail result appear in the panel and in the cable-schedule CSV.

Two simplifications understate this figure, and the panel discloses both. Resistivity is the 20 °C value; a conductor at its rated operating temperature is more resistive (≈ ×1.28 for copper at the 90 °C XLPE rating, ×1.20 at the 70 °C PVC rating). And only the resistive term is computed — reactance is neglected entirely, which matters more the larger the cross-section. The combined understatement is therefore material and grows with CSA; how much depends on the conductor material, the insulation, the phase count and the cable's actual reactance, none of which the tool asks for. Treat the 3 % check as indicative and confirm it against the standard.