How to Install Electrical Outlets in the Kitchen: Run new wiring without wrecking walls http://www.familyhandyman.com/electrical/wiring-outlets/how-to-install-electrical-outlets-in-the-kitchen/view-all
IF YOU LOOKED IN YOUR WALLS. You'd see a "network" of electrical wires. It could get confusing. The colors help MAP a plan for the electrician and when he installs the wires he then knows what wires should be connected. It helps so they dont have to rewire and helps prevent fires.