BlueDart, Not sure what you are referring to. Are you wiring an accessory with a positive and negative wire (being two wires) and a three position toggle type switch? If so then use the center terminal for the positive wire on the toggle switch and either of the other terminals that would go to the accessory. Then simply run the ground wire straight to the the ground source. Then your toggle switch will turn on and off your accessory circuit when you move the toggle switch from the center off position to the opposite of the wired side. If that doesn't make any sense, then let me know. JMHO