EPDM formulations were developed with both carbon black and aluminum hydroxide as fillers. Mechanical and electrical properties were evaluated with the purpose to find out those compositions which would meet the Brazilian Association for Technical Standards, ABNT requirements as for their use in wires and cables. As expected carbon black has a negative effect and its presence should be restricted to less than 22 phr if these materials are to be used in the range of medium voltages (up to 15 kV).