Another issue that needs to be considered is the nature of the ambient medium and the rate at which the heat dissipates into the ambient medium.

Thermal insulation would actually tend to impede heat dissipation from a conductor, whereas a conductor in free air could more easily dissipate heat, assuming that the conductor's ambient temperature is less than its operating temperature.

Finally, the last issue that is specifically mentioned in the Informational Note is the effect of adjacent load carrying conductors, which may both raise the ambient temperature and also impede heat dissipation.

Conductors in free air may more readily dissipate heat than conductors surrounded by thermal insulation.

Adjacent load carrying conductors may increase ambient heat and impede heat dissipation.