Because electric field lines and equipotential surfaces are always perpendicular, two equipotential surfaces can never cross;

Solution 11DQ Step 1 of 2: Field lines and equipotential surfaces are always mutually perpendicular. In general, field lines are curves, and equipotentials are curved surfaces. For the special case of a uniform field, in which the field lines are straight, parallel, and equally spaced, the equipotentials are parallel planes perpendicular to the field lines