NOVELTY - The apparatus has a fault condition detection unit i.e. control circuit (10), for detecting a fault condition. An electrical impedance changing unit changes electrical impedance of a coupling in response to the detected fault condition or in response to a normal transient condition. A set of operable contacts (9B) or a reactor (4) is used as a coupling element, where the electrical impedance changing unit is selected from one of an operable contact closing unit and a saturating or partial saturating unit for the reactor.    USE - Electrical apparatus for selectively coupling a circuit common to a monopole i.e. positive pole, and another mono-pole i.e. negative pole, of a bipolar solar photovoltaic array to earth or ground e.g. arbitrary zero or neutral reference point, for a solar photovoltaic power system (claimed).    ADVANTAGE - The apparatus safely disconnects the photovoltaic array from the earth or ground under a set of normal static operating conditions, where the apparatus senses voltage to earth on three terminals of the photovoltaic array and uses the operable contacts to selectively couple or uncouple a DC neutral point of the array to the earth or ground. The DC neutral point is allowed to float in a better manner when the terminals are within a rated voltage capability of the photovoltaic array.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a method for coupling a circuit common to a pair of mono-poles of a bipolar solar photovoltaic array through a reactor to earth or ground    (2) a method for allowing a circuit common to a pair of mono-poles of a bipolar solar photovoltaic array to float with respect to earth or ground or to be coupled to earth or ground though a high impedance under a normal static operating condition.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit diagram of an electrical apparatus.    Reactor (4)    Electromechanical contactor (9)    Actuator coil (9A)    Operable contacts (9B)    Control circuit (10)