Busbar Calculator
Size rectangular busbar assemblies in the browser, compare copper and aluminium candidates, review heating and clearance status, and export a PDF report without uploading project data.
What it does
Busbar Calculator is a client-side engineering aid for low-voltage panel and distribution busbar studies. Enter the electrical system, rated voltage, current, phase mode, material, rectangular profile, bar count, layout, cooling preset, and short-circuit assumptions. The utility then recalculates the selected profile, current density, resistance, losses, temperature forecast, channel envelope, clearance rule status, and short-circuit margins.
The app is built as a standalone micro-application under static/utility-apps/busbar-calculator. The CAD AutoScript shell embeds it in an iframe, so the calculator can evolve independently while sharing the same catalog, article, reactions, comments, and access layer as the other utilities.
When to use it
- Preliminary selection of copper or aluminium rectangular busbar sizes.
- Comparing one, two, three, or four bars per phase before panel layout work.
- Estimating losses per meter and steady-state temperature for a chosen cooling assumption.
- Checking whether phase gaps and enclosure clearances need review.
- Producing a quick PDF calculation note for design discussion or QA review.
Inputs and outputs
| Area | Inputs | Outputs |
|---|---|---|
| Electrical system | AC/DC, voltage, current, frequency, phase mode | Current density, resistance, losses per meter |
| Material and profile | Copper, aluminium, width, thickness, bars per phase | Area, mass, candidate ranking |
| Layout | Horizontal/vertical arrangement, flatwise/edgewise bars, gaps | Cross-section preview, phase centers, channel envelope |
| Environment | Ambient temperature, cooling preset, enclosure multiplier | Steady-state temperature, temperature forecast chart |
| Short circuit | RMS current, duration, peak current, support spacing | Thermal and mechanical pass/warn/fail status |
| Reports | Project, panel, tag, revision, engineer | PDF report, JSON import/export, CAD payload copy |
Important limits
The bundled material constants, profile ratings, cooling presets, and clearance rules are marked as example-only development datasets. They make the workflow testable, but they are not a certified design basis. Before releasing a real panel design, replace them with approved DIN, IEC, vendor, or project-specific data and validate the results against your engineering rules.
Workflow
- Enter project metadata and electrical ratings.
- Pick copper or aluminium and review the proposed profile candidates.
- Adjust bars per phase, phase spacing, orientation, and enclosure margins.
- Check the cross-section, current density, losses, and temperature forecast.
- Add short-circuit assumptions when they are known.
- Export a PDF report or JSON configuration for later review.
Assumptions & standards
- Standards basis: Sizing, thermal, and clearance checks are oriented on DIN 43670 / DIN 43671 busbar practice and IEC 60664 clearance concepts, using bundled example datasets rather than certified tables.
- Key assumptions:
- Steady-state operation at the entered current, ambient temperature, and cooling preset.
- Rectangular copper or aluminium bars with uniform material properties.
- Nominal profile dimensions without manufacturing tolerances.
- Short-circuit checks use the RMS current, duration, peak current, and support spacing exactly as entered.
- Limitations:
- The bundled material constants, profile ratings, cooling presets, and clearance rules are example-only development datasets, not a certified design basis.
- Transient thermal events, harmonics, and skin/proximity effects beyond the built-in model are not covered.
- Joint design, plating, torque values, and enclosure ventilation design are out of scope.
- ⚠️ The Busbar Calculator provides preliminary sizing support. Results must be verified by a qualified engineer against the governing code edition and the project specification before manufacturing or purchase.
Related tools
Feedback / bug report
- Open a GitHub issue
- Email or DM with the slug
busbar-calculatorso we can reproduce the issue.