Polymeric insulation is an increasing tendency in projects and maintenance of electrical networks for power distribution and transmission. Electrical power devices (e.g., insulators and surge arresters) developed by using polymeric insulation presents many advantages compared to the prior power components using ceramic insulation, such as: a better performance under high pollution environment; high hydrophobicity; high resistance to mechanical, electrical and chemical stresses. The practice with silicone insulators in polluted environments has shown that the ideal performance is directly related to insulator design and polymer formulation. One of the most common misunderstandings in the design of silicone compounds for insulators is the amount of inorganic load used in their formulation. This paper attempts to clarify how the variation of the inorganic load amount affects physicochemical characteristics of different silicone compounds. The physicochemical evaluation is performed from several measurements, such as: density, hardness, elongation, tensile strength. In addition, the evaluation of the physicochemical structure is carried out using infrared test and scanning electronic microscopy (SEM). The electrical analysis is performed from the electric tracking wheel and erosion test, in agreement with the recommendation of the International Electrotechnical Commission (IEC).©2014 Elsevier Ltd. All rights reserved.5016373Mackevich, J., Shah, M., Polymer outdoor insulating materials Part I: Comparison of porcelain and polymer electrical insulation (1997) IEEE Electrical Insulation Magazine, 13 (3), pp. 5-12Kindersberger, J., Service performance, material design and applications of composite insulators with silicone rubber housings (1996) CIGRÉ Session, , SC 33-303, ParisGonzalez, E.G.C., (1999) Desenvolvimento de Compósitos de Silicone Para Uso em Isoladores de Linhas de Transmissão - M. Sc. Dissertation, , Rio de JaneiroSilva, D.A., Costa, E.C.M., Franco, J.L., Antonionni, M., Jesus, R.C., Abreu, S.R., Lahti, K., Pissolato, J., Reliability of directly-molded polymer surge arresters: Degradation by immersion test versus electrical performance (2013) Int. J. Elect. Power Energy Syst., 53, pp. 488-498Plano Decenal de Expansão, 1999-2008, , ELETROBRÁS, 1999, Programa decenal de transmissãoSwift, D.A., (1995) Hydrophobicity of Silicone Rubber Insulators: Some Intriguiding Experimental Findings, , Colloquium CIGRE SC 33-303, 3.2, Harare, ZimbabweRiquel, G., Formigue, J.M., Decker, D., Parraud, R., Natural and artificial ageing of non-ceramic insulators evaluation of diagnostic techniques (1995) 9th Inter. Symp. High Voltage Engineering, 3184-1/4, , AustriaYoshimura, N., Kumagai, S., Nishimura, S., Electrical and environmental aging of silicone rubber used in outdoor insulation (1999) IEEE Transactions on Dielectrics and Electrical Insulation, 6 (5), pp. 632-650. , DOI 10.1109/94.798120(1998) Norma NBR 10296, Material Isolante Elétrico - Avaliaç ão de Sua Resistência Ao Trilhamento Elétrico e Erosão Sob Severas Condições Ambientais, ABNT Associação Brasileira de Normas Técnicas, São Paulo(1995) IEC 61109 - Composite Insulators for AC Overhead Lines with A Nominal Voltage Greater Than 1000V Definitions, , test methods and acceptance criteria(2005) IEC 62217 - Polymeric Insulators for Indoor and Outdoor Used with A Nominal Voltage Greater Than 1000 v - General Definitions, Test Methods and Acceptance Criteria, First Edition(2006) ASTM D412 - Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers-TensionASTM D624 - Standard Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomers, 2000-2001(2004) ASTM D 2303 - Standard Test Methods for Liquid-Contaminant, Inclined-Plane Tracking and Erosion of Insulating MaterialsBlackmore, P.D., Birtwhistle, D., Cash, G.A., George, G.A., Condition assessment of EPDM composite insulators using FTIR spectroscopy (1998) IEEE Transactions on Dielectrics and Electrical Insulation, 5 (1), pp. 132-141George, G.A., Celina, M., Vassallo, A.M., Cole-Clarke, P.A., Real-time analysis of the thermal oxidation of polyolefins by FTIR emission (1995) Polym. Degrad. Stab., 48, pp. 199-210