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SHORT-TIME CURRENT RATING OF CABLES, CONDUCTORS, AND BUS BAR

The following calculator computes the expected time for a cable, conductor, or bus bar to rise in temperature under short circuit or short-time overcurrent conditions. The calculator uses empirical formulas that consider all heat generated by I2R losses in the conductor during an overcurrent condition to be absorbed by the conductor and that no heat is transmitted from the conductor to its surroundings.

Calculator-1


Known variables: Conductor cross-sectional area (Circular Mils), Conductor Material, Short Circuit/Overload Current (RMS Amperes), Operating Temperature, Maximum Temperature



     
Input Conductor, Current, and Temperature Details
Choose Conductors:
 
Choose Conductor Material:
 
Conductor area:   
Input Short Circuit/Overload Current:   
Input Operating Temperature:
 
Input Maximum Temperature:
 
     
Calculation Results
 Time to Reach Maximum Temperature:  Seconds  
       
 

Formulas and Variables


Copper Conductors





Aluminum Conductors


Where:

T = Time Duration of Short Circuit/ Overcurrent Condition (seconds)
Θ1 = Operating Temperature (degrees Celsius)
Θ2 = Maximum Temperature (degrees Celsius)
A = Cross-Sectional Area of Conductor
I = Short Circuit / Overload Current (RMS Amperes)

Conductor / Cable / Bus Bar Data


Tables below provide circular mil and area information for various size conductors and bus bar for reference purposes.