Method and apparatus for a mechanical latching of at least one pole of a relay selected from SPST, SPDT, DPDT, reversing DPDT, multi pole MPST and MPDT using a mechanical latching device attached to or actuated by an armature for pulling a springy element for maintaining engagement between at least one pole contact and at least one of a terminal contact, including PCB assembly for controlling the relay and operating electrical loads by feeding electric power pulse to a relay coil for pulling the armature including a CPU program for providing communication and controlling for the relay to switch on-off or change over, or from cross to straight and straight to cross.