Wiring and Protection
Contact Resistance Loss Calculator
Contact Resistance Loss converts the entered electrical measurements into contact power loss. Use it to the contact power loss calculation.
Enter values for contact power loss
Use one consistent electrical operating case for all fields.
How Contact Resistance Loss works
This worksheet evaluates loss = I²Rcontact. Contact Resistance Loss uses Current, Contact resistance to report Contact power loss.
With the loaded values, contact power loss evaluates to 5.00 W. Hold the remaining entries steady while testing an uncertain input. Use Bundled Cable Derating Calculator as the follow-up for bundled ampacity.
Inputs for Contact Resistance Loss
Current and Contact resistance belong to Contact Resistance Loss. Keep source units with current.
The sample case is a worked example, not a design target.
- Current
- Example entry: 50 A.
- Contact resistance
- Example entry: 0.002 Ω.
Reading the Contact Resistance Loss result
This output represents Contact Resistance Loss.
Compare the output with equipment limits and the applicable design margins.
Measurement and units
Treat these results as planning arithmetic; conductor and protective-device selection must follow the applicable electrical code and equipment instructions. Check prefixes on current.
Record conversion choices so comparisons stay traceable.
Limits of this calculation
Milliohm-level readings require suitable four-wire measurement. If the next question concerns minimum circuit rating, open Continuous Load Capacity Calculator.
Only the stated inputs participate in this simplified model. Unentered effects remain outside Contact Resistance Loss.
Questions about Contact Resistance Loss
What does Contact Resistance Loss calculate?
Contact Resistance Loss reports contact power loss.
Can Current be zero?
For Contact Resistance Loss, measure any zero current directly.
Why can contact power loss differ from measurement?
Milliohm-level readings require suitable four-wire measurement. Recheck current.