This paper deals with the wire-grid representation of metallic surfaces in numerical electromagnetic modeling. We discuss in particular the adequacy of the well known and widely used equal area rule (EAR) to calculate the radii of wire-grid models. We show that the EAR is accurate as long as the wire grid consists of a simple rectangular mesh. For more complex body-fitted meshes, using other polygons such as triangles, the EAR appears to be less accurate in reproducing the electromagnetic field scattered by metallic bodies. The conclusions of the paper are supported by numerical simulations performed using a parallel version of the numerical electromagnetics code and experimental data obtained on a vehicle illuminated by an electromagnetic pulse simulator