For 1,000 feet of 18 gauge copper at 167°F, the resistance is 8.08 ohms. Which of the following lists this value correctly?

For 1,000 feet of 18 gauge copper at 167°F, the resistance is 8.08 ohms. Which of the following lists this value correctly?

• A. 7.77
• B. 7.95
• C. 8.08
• D. 8.45

Answer: (C)

The concept being tested is how resistance of a copper conductor is tied to length, material, and temperature. For a fixed length (1,000 feet) of a specific gauge, the resistance at a given temperature is a single value. Copper’s resistance increases with temperature, so tables give the resistance per 1,000 feet at a specified temperature, and you apply the temperature correction to get the final value. In this problem, the resistance for 1,000 feet of 18 gauge copper at 167°F is given as 8.08 ohms. The option that matches this exact value—8.08 ohms—is the correct listing. The other numbers differ from 8.08 and would represent different readings or rounding, but they do not match the stated resistance at that temperature.

The concept being tested is how resistance of a copper conductor is tied to length, material, and temperature. For a fixed length (1,000 feet) of a specific gauge, the resistance at a given temperature is a single value. Copper’s resistance increases with temperature, so tables give the resistance per 1,000 feet at a specified temperature, and you apply the temperature correction to get the final value.

In this problem, the resistance for 1,000 feet of 18 gauge copper at 167°F is given as 8.08 ohms. The option that matches this exact value—8.08 ohms—is the correct listing. The other numbers differ from 8.08 and would represent different readings or rounding, but they do not match the stated resistance at that temperature.