The connector (11) is made up of electroinsulator supports (1, 2) carriers of at least one pair of terminals (3, 4) capable of coupling to a plug said terminals (3, 4), being in a coupling position for said electroinsulator supports (1, 2), electrically joined to each other establishing a channel (5) for the passing of electrical energy towards said power load (10), the method and system being made up of a connection (15) between a point (23) of said channel (5) near to the load (10) and after the connector (11), whose connection passes through the connector (11), in order to detect a voltage (V2) and/or intensity in the second point (23), which is compared with the voltage (V1) of supply, and in the event of a sudden change being observed, said supply is cut off.