Calculator
Example Data Table
| Working Voltage (V) | Pollution | Material | Insulation | Altitude (m) | Margin (%) | Recommended Creepage (mm) | Recommended Clearance (mm) |
|---|---|---|---|---|---|---|---|
| 230 | 2 | II | Basic | 0 | 15 | 1.20 | 1.80 |
| 400 | 3 | IIIa | Reinforced | 1500 | 20 | 4.75 | 4.10 |
| 48 | 2 | I | Basic | 2500 | 10 | 0.35 | 1.10 |
These rows are illustrative. Your real requirements can differ by standard, insulation system, and construction details.
Formula Used
This calculator uses planning-level models to estimate spacing. Creepage is driven by surface tracking risk, while clearance is driven by air breakdown risk.
- Vpk (peak voltage) = Vrms × √2 for AC, or equals voltage for DC/pulse peak.
- Creepage (mm) ≈ 4.0 × (Vrms/1000) × Fpd × Fmat × Fins × Fhum × Fcoat
- Clearance (mm) ≈ (0.8 + 1.6 × (Vpk/1000)) × Fins × Fov × Falt
- Safety margin: multiply both by (1 + margin%/100), then round up to your step.
Use this output for early sizing and comparisons, then verify with the correct tables, test requirements, and certification constraints.
How to Use This Calculator
- Enter the working voltage and choose how the value should be interpreted.
- Select overvoltage category, pollution degree, material group, and insulation type.
- Set altitude, humidity, and coating state to match your environment.
- Add a safety margin and rounding step that fits your fabrication process.
- Click Calculate, then export the result for documentation.
FAQs
1) What is creepage distance?
Creepage is the shortest path along an insulating surface between conductors. It matters when contamination, moisture, or tracking can create conductive paths and leakage.
2) What is clearance distance?
Clearance is the shortest through-air distance between conductors. It prevents arcing through air, especially during transients and at reduced air density.
3) Why does pollution degree change creepage?
More pollution increases the chance of surface conduction and tracking. Higher pollution degrees usually require larger creepage to maintain long-term reliability and safety.
4) How does CTI affect spacing?
CTI reflects how well a material resists tracking. Higher CTI materials can allow shorter creepage under the same conditions, depending on your ruleset and certification path.
5) Does altitude affect creepage too?
Altitude mainly affects air breakdown, so clearance increases. Creepage is surface-based, so altitude is usually secondary unless it changes humidity, condensation, or contamination behavior.
6) Can conformal coating reduce creepage needs?
Sometimes, if the coating system is qualified and manufacturing controls are strong. Many standards require specific evidence, test data, and process verification before reductions are accepted.
7) What safety margin should I use?
A common planning range is 10–30%, depending on tolerances, expected aging, contamination risk, and audit requirements. Use your internal guidelines or certification feedback.
8) Are these values compliant with every standard?
No. Standards differ by product category, insulation system, and test approach. Use these results for early design, then confirm using the exact tables and clauses you must meet.