What is the DC resistance at 75°C for 1,000 feet of no. 4 AWG copper, uncoated wire?

To determine the DC resistance of 1,000 feet of no. 4 AWG copper wire at 75°C, it is essential to understand how wire resistance is calculated and the impact of temperature on resistance.

The resistance of copper wire is influenced primarily by its gauge and temperature. The standard resistance of no. 4 AWG copper wire is approximately 0.2485 ohms per 1,000 feet at 20°C (room temperature). However, as the temperature increases, the resistance of the wire also increases due to the properties of the material.

To adjust for temperature, a temperature coefficient for copper can be applied. The coefficient is roughly 0.004 per °C. This means for every increase in temperature, the resistance will increase by approximately 0.4% of its resistance at 20°C.

Calculating the increase from 20°C to 75°C (an increase of 55°C):

1. Original resistance at 20°C = 0.2485 ohms.

2. Increase in resistance per °C = 0.2485 ohms * 0.004 * 55 = 0.05474 ohms.

3. Total resistance at 75°C = 0.248