Fast Cooling Busbar Insulation

Cool-Running Epoxy-Insulated Power Transmission Gear

Epoxy-coated busbars improve safety without increasing operating temperature – according to recent testing at SolEpoxy labs. Bare bars were tested side-by-side with bus bars coated in epoxy, wrapped in mylar, and surrounded by polyolephin shrinktube.


As expected, the mylar and shrinktube-wraped bus bars cooled down more slowly than did bare copper and aluminum bars.

Surprisingly, epoxy-coated copper bus bars cooled just as fast as bare copper. Bare aluminum cooled only slightly faster than epoxy-insulated aluminum.

This test demonstrated that DK15-0907, UL-listed epoxy composite, yields electrical insulation without sacrificing heat transfer.

We gathered data in Figure 1 using bars coated with 1.5mm of epoxy -- sufficient to insulate 15 kV. Low voltage busbars – typically 600V, and used for power distribution in large buildings, require less than 0.5mm of Epoxy for a tough, durable electrical insulation. At this thickness, we found a surprising result!

Fusion Bonded Epoxy May Actually Improve Heat Transfer


In a separate experiment, we compared cooling rate as a function of epoxy coating thickness. The graphs above depict the results, with the black lines representing cool down time of bare bar in both graphs. Thin epoxy – approximately 0.5mm, actually improved heat transfer from both Copper and Aluminum busbars! We are still experimenting but we suspect that the fusion-bonded epoxy may improve emissivity. Red and black epoxy performed about the same. A gloss finish performed just as well as a flat finish.

Epoxy-coated busbars can provide improved safety without substantially effecting heat transfer from the conductors. This is an important insight for engineers who are designing the future around e-mobility, micro-grids, and the electrification of everything. To keep up with insulation trends, contact SolEpoxy for by emailing or calling (716)-372-6300.