Cable short-circuit thermal equation
The same adiabatic relationship can check required area, maximum time, or withstand energy.
I²t ≤ k²S²Smin = I × √t / ktmax = (kS / I)²where:
- I
- Short-circuit current[A]
- t
- Fault duration[s]
- S
- Conductor cross-section[mm²]
- k
- Conductor and insulation constant[A√s/mm²]
Use the exact protective-device clearing time at the calculated fault current.
How to use the Cable Short-Circuit Thermal Withstand Calculator
Check cable short-circuit thermal withstand using conductor area, fault current, duration, and material k value. Start by choosing the operating mode, then enter values from nameplates, measurements, or project documents in the units shown. The result updates immediately and keeps intermediate quantities visible for review.
- Confirm the system and calculation mode.
- Enter measured or manufacturer-rated values.
- Review the primary result and intermediate metrics.
- Continue with the related protection or equipment-selection checks.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. Adiabatic short-duration heating Entered k value represents the actual conductor and insulation temperature limits A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Adiabatic short-duration heating
- Entered k value represents the actual conductor and insulation temperature limits
Selection limits and next checks
Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
Continue with protective conductor size calculatorContinue with short circuit current calculatorContinue with cable derating factor calculator
Assumptions
- Adiabatic short-duration heating
- Entered k value represents the actual conductor and insulation temperature limits
Important Warnings
- Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions.