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

We know that the electric field lines for a point charge are directed radially outwards or inwards with the point charge as the centre depending upon whether the charge is positive or negative. We also know that the equipotential surfaces are always perpendicular to the electric field lines. So the equipotential surfaces for a point charge are the spheres centred at the point charge, since the electric field lines are directed along the radial direction.