Power Cable Rating Calculations - A Historical Perspective [History]

The thermal rating of power cables and wiring installations has received much attention since the advent of electricity in the late 19th and the early 20th centuries and today is still the subject of numerous scientific investigations. The first observations on this subject were made while the first electric telegraph systems and distribution lines for electric lighting were being developed by early pioneers in the 1820s and 1880s, respectively [1]. One of the first publications on this subject was by Forbes in 1884 [2] and by Kennelly in 1889 with his conference paper "Heating Conductors by Electric Currents" [3]. Some years later, Kennelly published another paper, "On the Carrying Capacity of Electric Cables, Submerged, Buried, or Suspended in Air," [4] (see Figure 1) and a book addressing the heating effects in currentcarrying conductors [5]. During the same period, in 1894, Jenks coauthored a book, Electricity as a Fire Hazard [6], where he presents the state of the art on the development of design rules and guidelines for electric installations and also several definitions for the safe current-carrying capacity of conductors on the basis of the publications of various authors such as A.E. Kennelly and E. Atkinson.