s-4 northern computers suppressor kit wiring 781305114271 s4 quantity 2 in on kit(pack) s4 suppressor kit for reade(d) the s-4 kit must be installed w/ every electrical switching device and connected through a relay contact on the n-1000, n-800 and n-500. the s-4 suppressor kit protects products from the power generated by the collapsing electrical field of an electromagnetic device. when installed properly, the kit provides the collapsing field a proper path to ground, which protects the panel from interruption and damage. the s-4 suppression kit consist of two identical pieces. the s-4 connecting wires are non-polarized and the two parts included in the suppressor kit are identical to each other. one part of the s-4 kit is installed across the relay contacts, without regard to polarity. the second is installed within 18 inches of the electrical switching device, without regard to polarity. each piece consists of a resistor, capacitor and transzorb network. these parts are encapsulated in a rubber like insulating material. . 781305114271