Wiring and Protection
Insulation Leakage Current Calculator
Use Insulation Leakage Current when leakage current is the quantity you need. Enter test voltage and insulation resistance, then compare the answer with the equipment or operating limits that apply to your case.
Run the Insulation Leakage Current scenario
Check the source and units before calculating.
Compare two operating cases
Change Test voltage from 500 V to 600 V with the rest of the inputs held constant. The comparison runs from 25.00 µA to 30.00 µA.
Do not average the two cases if either could define an operating limit.
Leakage current: calculation method
The arithmetic is based on I = V ÷ R. The participating entries are Test voltage and Insulation resistance.
The defaults produce 25.00 µA. Replace them with measurements from one operating state.
Calculate leakage current from test voltage and insulation resistance. For the companion estimated ground resistance calculation, open Ground Electrode Resistance Calculator.
Preparing the calculation
Keep one-way and round-trip lengths clearly identified. Nameplate and meter values are not interchangeable unless they describe the same condition.
A denominator entry cannot be zero. Use the displayed unit for every field and document conversions separately. Another relevant worksheet is Battery Internal Resistance Calculator.
- Test voltage
- Default example: 500 V. Enter test voltage in V.
- Insulation resistance
- Default example: 20 MΩ. Enter insulation resistance in MΩ.
Interpreting the answer
Use Leakage current as one quantified check within the larger decision. Compare it with the selected conductor and protective-device ratings.
A result without its source conditions is difficult to compare or audit. If you also need contact power loss, continue with Contact Resistance Loss Calculator.
Using the answer downstream
Record test voltage and insulation resistance with leakage current. Include the operating state and data source.
Transfer leakage current with all available digits during downstream arithmetic. Round at the final reporting step.
What the formula leaves out
Follow the equipment test-voltage limit.
Outside the entered variables, consider fault duration, protective-device curves, and conductor thermal limits. Do not hide omitted behavior inside an unexplained correction factor.
Record ambient temperature, bundling, insulation class, and termination conditions. Continue to Extension Cord Power Loss Calculator if cord loss is also needed.
A final reasonableness check
Review insulation resistance and the remaining entries as one case. If one value belongs to another temperature, load, or time period, separate the scenarios.
The displayed leakage current should be checked against the selected conductor and protective-device ratings. Investigate an unexpected magnitude before changing the model or adding margin.
Document any effect handled outside this page, especially code rules, manufacturer instructions, and field installation details. That note prevents a later reader from assuming the simple equation covered it.