Abstract: Currently, remote powering over the Ethernet (including PoE, PoE+, etc.) has emerged as a cost-effective option to power networked devices using balanced twisted pair cabling. Power delivery through Ethernet cables has numerous benefits including space saving and, of course, the ‘green’ benefit of using fewer natural resources. However, this raises several questions: could a combination of the transmission of high power and consequent increased ambient (local) temperature affect the performance of the cable dielectrics? How far would the change in the dielectric property affect cable performance, including throughput and Ethernet signal integrity? The dielectric constant of different insulation types used in Ethernet cabling was examined at a room temperature to establish performance at 1GHz, 2.4GHz and 5GHz. Then, at 60 degC to observe the effect of an increase in temperature on the performance of the dielectrics across the three frequencies. Moreover, Foamed-Skin HDPE was thermally cycled between the room temperature and 60 degC to study the effect of thermal variation on its dielectric constant. The last study cycled the Foamed-Skin HDPE up to 90 degC to observe both the transient and permanent changes in the value of the dielectric constant. In this study, it was found that increase in temperature has effects on the dielectric constant of all the dielectrics evaluated from the first heating cycle. In addition, thermal cycling showed a remarkable non-reversible modification in the dielectric constant of the Foam-Skin HDPE at 60 degC. The study further established the marked effect of an increase in ambient temperature on the physical and rheological behavior of dielectric materials.