Question

What is the ampacity of a number 10 type TW copper wire in a raceway containing 6 wires and located in an area where the ambient temperature is 50 degrees Celsius?

a) 25 A
b) 30 A
c) 35 A
d) 40 A

Answer 1

The adjusted ampacity of a number 10 type TW copper wire at 50 degrees Celsius in a raceway with 6 wires is below 25 A when considering the ambient temperature correction factor and the adjustment factor for the number of wires. The base ampacity at 30 degrees Celsius is 30 A, which is derated to approximately 18 A under these conditions. The correct option is A) 25A.

Step-by-step explanation:

The ampacity of a number 10 type TW copper wire in a raceway containing 6 wires and located in an area where the ambient temperature is 50 degrees Celsius can be determined by referring to the National Electrical Code (NEC) tables for wire ampacity, taking into consideration the ambient temperature correction factors and adjustment factors for the number of conductors in a raceway. First, we look at the base ampacity for a number 10 type TW wire, which is typically 30 amps at 30 degrees Celsius. However, when the ambient temperature is 50 degrees Celsius, there needs to be an adjustment made. Consulting the NEC temperature correction factors, we see that at 50 degrees Celsius, the ampacity needs to be derated to approximately 75% of its base value. Moreover, when more than three current-carrying conductors are bundled together, as is the case with 6 wires in the raceway, an additional derating is required. This adjustment factor, according to the NEC, is approximately 80% for 4 to 6 conductors. Therefore, to find the adjusted ampacity for the number 10 type TW copper wire in this scenario, we multiply the base ampacity of 30 amps by both the ambient temperature correction factor (0.75) and the adjustment factor for the number of conductors (0.80), which results in: 30 A × 0.75 × 0.80 = 18 A Since this value does not match any of the options provided (a) 25 A, (b) 30 A, (c) 35 A, (d) 40 A, we would need to re-evaluate the options or question validity. However, based on standard calculations, the closest correct answer would be under 25 A, indicating that option (a) would be selected if the question is considered to contain a typo or error.