What is the ampacity of each 12 AWG conductor when installed in a one-inch EMT with twelve conductors at an ambient temperature of 32°C?

To determine the ampacity of a 12 AWG conductor installed in a one-inch EMT (Electrical Metallic Tubing) with twelve conductors at an ambient temperature of 32°C, it is essential to refer to the National Electrical Code (NEC) and the associated ampacity tables.

The base ampacity for a 12 AWG conductor generally is around 20 amps when considering individual conductors in free air at 30°C. However, when multiple conductors are installed together, the ampacity must be adjusted due to factors such as derating. The NEC specifies that when conduits contain multiple conductors, the ampacity should be reduced based on the number of conductors to account for increased heat from the combined current flow.

For twelve conductors in a conduit, the derating factor is significant, typically reducing the ampacity to approximately 40% of the base rating. When applying this factor to the original ampacity of 20 amps, the calculation leads to:

[ 20 \text{ A} \times 0.40 = 8 \text{ A} ]

However, this initial calculation does not yet factor in the slight increase due to the ambient temperature of 32°C compared to the standard 30