First, we cut a 5m long sample of the stranded conductor. Then we fix the contact clamps for the measurement one meter apart from each other on the sample conductor. Then we use a Kelvin Double Bridge to measure the DC resistance of the conductor between the clamps. Also, we can use a micro-ohm meter for the purpose. We shall repeat the measurement at least 5 times, switching on and off the measuring instrument. Then, we calculate the average of these five measured DC resistances. Also, we must record the temperatures during the measurements.
Temperature Correction
Then we correct the average measured DC resistance value at 20°C. The formula for correcting resistance at 20°C, is
Where R20 is the corrected resistance at 20°C, and RT is the measured DC resistance at ToC. This formula is given in IS:398-(Part-IV)/(Part-V).
