We study the role of the electrical double layer (EDL) in the formation of the quasistatic electrical conductivity of suspensions of nanosized particles. A suspension is viewed as a system of hard-core--penetrable-shell particles. The shells are electrically inhomogeneous, with a radially symmetrical conductivity profile. It is assumed that the real microstructure of the suspension can be reflected in terms of this profile and also the rule of dominance for overlapping regions that the local conductivity in the system is determined by the nearest particle. Using our earlier rigorous results for systems with this morphology, we derive general integral relations for the desired conductivity which incorporate the effect of the EDL and make it possible to look into the contributions from its different parts and parameters. Specific features, internal consistency, and flexibility of the model are demonstrated by further elaborating it to describe experimental data for latex suspensions in aqueous electrolyte solutions with high ionic strength.

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