Power cable coating compounds are disclosed, the coating compounds including an ethylene alpha-olefin diene elastomeric terpolymer, and an ethylene alpha-olefin copolymer having a Melt Index Ratio I.sub.10/I.sub.2 of at least 7 and/or a Melt Index Ratio I.sub.21/I.sub.2 of at least 20. In various embodiments, the ethylene alpha-olefin copolymer can be present in the coating compound in amounts up to 90 percent by weight, based on the weight of the ethylene alpha-olefin diene elastomeric terpolymer and the ethylene alpha-olefin copolymer. Also disclosed are electrical devices including extruded coating compounds, the extruded compounds having low surface roughness at high extrusion rates.