Home Electrical Basics

Of the many kinds of home repairs, electrical ones tend to intimidate homeowners the most. Not only does wiring seem confusing, but the specter of electrical shock is scary. What most people don’t realize, however, is that doing certain jobs on your home’s electrical systems can be easy and safe if you follow basic safety precautions. The key to safety is to always disconnect the power from an electrical system before working on it.

Some electrical systems are safer and easier to work on than others: Most low-voltage, telephone, doorbell, and cable television wires, for example, are relatively harmless and easy to handle compared to standard-voltage lights and receptacles.

Lights, receptacles, and appliances are all connected to the primary standard-voltage system that is delivered through power lines by your electrical utility and then routed throughout your home’s wiring. Before working on any elements of the primary electrical system in your home, you must disconnect the power. Turning off a wall switch does not necessarily turn off the power to a fixture or receptacle; you must shut off the power at the circuit breaker.

Three wires enter most homes from the power pole—two “hot” wires and a third “neutral” wire. Each hot wire provides 120-volt current for conventional lights, receptacles, and appliances when paired with the neutral wire, which is normally kept at zero volts or “ground potential.” When both hot wires are used together with the neutral, they power large 240-volt appliances such as air conditioners and electric ovens.

In addition, most homes have low-voltage electrical systems with transformers that convert standard power to a lower, safer voltage (typically from 6 to 12 volts) for doorbells, intercoms, security systems, low-voltage interior and exterior lighting, and the like. Low-voltage electricity is also delivered through telephone lines for ringing phones. Audio and video or cable television signals travel through cables that, under normal circumstances, have no voltage.