Look at the colors used for the wires represented on a wiring diagram. The black wire is typically a hot wire which carries the power to a light, outlet or switch. Any additional hot wire will be colored red. The white colored wire line represents the neutral wire used in alternating current diagrams, such as those illustrating household electrical circuits. The green color shows the paths of the ground wires.
Read wiring diagrams to identify the red colored wires with designations, such as "travel" or "hot" wires. There are two hot wires that carry power to an outlet or appliance in a 240-volt wiring scheme. One is shown black and the other is shown red. A red wire on a light switch diagram is traveling to carry power from one switch to another in a 3-way or 4-way system.
Notice the colors of the terminals on switches and outlets. One is colored dark brown to show that it's the "common" terminal which is slated to receive the incoming hot wire. The other terminals may be colored silver or clear to distinguish them from the common. Ground terminals are colored green.
Follow the trails of the wires drawn on the diagram to show where both ends connect, but do not decipher the connections to terminals exactly as shown. Many electrical wiring diagrams show multiple wires connecting to the same terminal on an outlet or switch. This is not how the wiring is done. Only one wire connects under a screw terminal. The other wires shown meeting at a terminal actually connect to each other under a wire nut, a few inches away from that terminal.
Use the colors on a wiring diagram as a close reflection of actual wire and terminal colors used in electrical systems. The green color for ground wires is often the exception, in that it only depicts ground wires with insulation. Many electrical cables have bare copper ground wires with no insulation of any color. Otherwise, hot wires are red and black, neutral wires are white, common terminals are a dark brass color, the other terminals are silver screws and ground terminals are screws dyed green.