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Electrical: The Bare Essentials of Residential Wiring

If you plan to do any electrical repairs or additions to your home and are not completely familiar with how your home’s electrical system works, please review the following basics; or even better, read a book on making electrical repairs. While the knowledge found on a single page will not allow you to wire your next home, it will provide some helpful tips and warnings that can help you avoid creating electrical hazards when installing switches, receptacles, or making simple electrical repairs.

The electrical current in your home is known as 60 Hertz or cycle, AC, that is, alternating current that reverses its flow 120 times or 60 cycles per second. (The current is actually turning on and off 120 times each second, but it happens so fast the human eye cannot detect it. That’s one reason the early compact fluorescent bulbs caused nausea or headaches for some. The bulbs reacted more slowly than incandescent and made the on/off cycling more apparent.) Almost all homes are served with 240 volts of electricity that is distributed through the circuit breaker panel (common in most homes) or the fuse box (found in older homes) into circuits that require either 240 volts or 120 volts.

A quick look inside a circuit breaker panel reveals black, white, an occasional red, and bare copper wires. The black and the red wires are connected to the “hot” side of a circuit, and the white wires to the “negative” side. The bare copper wire is considered the ground; and many are confused by the fact that the ground and white wires are connected to the same terminals in the circuit breaker panel. While that is the case, the bare or ground wire was added many years ago to provide additional protection. Many older homes lack the ground wire and their receptacles are 2-prong, not the more common 3- prong found today.

The ground is truly a connection directly to the earth through a connector attached to a water pipe or a “ground” rod that is actually driven into the ground outside the home. Newer homes use a better, more reliable grounding system, and include a steel rod buried into the footings underneath the foundation.

When installing light fixtures, switches, receptacles, or other electrical devices, NEVER IGNORE THE GROUND WIRE. Connect per the manufacturer’s recommendations for the device you are installing.

Electrical testerIn many homes with metal switch and receptacle boxes, the box itself is connected to ground, and this can be checked with a simple tester, with one lead connected to the hot side of the circuit and the other touching the metal box. If you encounter grounded boxes, you can ground devices installed in them with a ground clip or by installing a green grounding screw in the threaded hole at the rear of the metal box.

As this is only a rudimentary explanation of your electrical system, please remember the following:

  • Turn off the power to circuits you’re working on; when in doubt turn off the main breaker.
  • Use a tester to make certain the power is off.
  • The wires on a switch can shock even if the switch is turned off.
  • It’s possible to receive an electric shock from the white or neutral wire.
  • Wearing rubber gloves can help, but not eliminate, the danger of electric shock when making electrical repairs.
  • Never twist wires and wrap with electrical tape; use electrical connectors of the proper type.
  • Improper electrical connections pose a significant fire hazard.
  • Never attach more than one circuit to a single circuit breaker.
  • While ignorance may be bliss, when working with electricity it CAN BE DEADLY.
  • If none of the above makes sense, call an electrician. While you may think their fee will cost an “arm and a leg,” it’s much cheaper than the price of your life.


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