Which of the following is NOT a factor for determining conductor size?

The determination of conductor size is based on various technical factors that affect electrical performance and safety. Length of run is critical because it influences voltage drop along the wire; longer runs result in greater resistance and can lead to inefficient power delivery. Ambient temperature is important as it affects the conductor's ability to dissipate heat, which in turn impacts its current-carrying capability. The type of insulation is also significant since it determines how much current the conductor can safely carry under certain conditions and helps in preventing voltage breakdown.

In contrast, the color of the wire does not influence its electrical properties or capacity. Wire color is primarily for identification purposes, aiding in wiring applications to ensure that connections are made correctly and safely, but it does not have a direct bearing on the wire’s size or its ability to carry electrical current effectively. Therefore, identifying that the color of the wire is not a factor in determining conductor size is the reason it stands out as the correct answer in this context.