What is Grounding?

Now that you know what kind of current you have in your house (and everywhere else), let’s discuss another critical feature—grounding. Your entire electrical system, if it’s up to current code, is grounded for your protection. This literally means that one wire of your electrical system leads back into the earth itself, where it will carry any errant current that could otherwise shock or electrocute you. The earth ends up being a good electrical conductor and a convenient return path for electrons. In fact, the earth is used as a reference point for measuring the voltage in our electrical systems.
A ground wire can be attached to a ground rod that is deeply buried, or it can be a length of copper wire buried near your foundation’s footings. A second physical ground is usually your cold-water supply pipe near your service panel.
Modern house wiring is color-coded so you won’t confuse your hot, neutral, and
ground wires with one another. This coding is standard everywhere—there is no room
for artistic creativity here. The wire colors are …

• Black and red for hot wires
• White for neutral wires
• Bare (unsheathed) copper or green for ground wires

The black, red, white, and green colors refer to the plastic sheathing that contains the wires themselves. If you have an old two-wire system , you won’t have a ground wire. An old knob-and-tube system sheaths both the hot and neutral wires in black, which isn’t exactly user-friendly when you’re trying to distinguish one wire from another. It’s important to understand the difference between the grounding wire and the neutral wire.
The neutral white wire carries the electrical current back to the power source after it’s passed through a load (a ceiling light, a fan, a stereo, and so on).
That’s the nature of an alternating current. The grounding wire, on the other hand, protects the entire system. The neutral wire is more correctly referred to as a grounded conductor. The bare or copper wire is a grounding conductor.