I once had a friend do some rewiring for me. First he installed lengths of tubing through which the wires would pass. Then from box to box, from terminal to terminal, he pulled long lengths of thick, insulated wire. Each length of wire contained three other wires, each well insulated and each a different color—red, black, and white. My friend kept those wires separate and paid careful attention to the color code. He did not indiscriminately link together red and black,