Equipotential at a great distance from a collection of charges whose total sum is not zero are approximately

For equipotential surface, these surfaces are perpendicular to the field lines. So there must be elect c field, which cannot be without charge.
So the algebraic sum of all charges must not be zero. Equipotential surface at a great distance means that space of charge is negligible as compared to distance. So the collection of charges is considered as a point charge. l-le(bi. potential due to point charge is,
$\mathrm{V}={\mathrm{k}}_{\mathrm{e}}\frac{\mathrm{q}}{\mathrm{r}}$
which explains that electric potentials due to point charge is same for all equidistant points. The locus of these equidistant points, which are at same potential, forms spherical surface.