Homeowners may not give it much thought, but there's a lot that goes into the process of providing power to your home. Each time you flip a light switch, you're tapping into a massive and complex power grid.
Transformers near your home reduce high voltage current to the 110-220-volt lines used in homes, while an electric meter records the amount of power drawn into your home. Those are just two of many important components used to keep your lights on and appliances running.
How do circuit breakers work?
Perhaps the most important safety feature in household electrical systems is the circuit breaker, which instantly cuts off power when there is an overload.
In modern homes, a circuit breaker panel (often called the breaker box) can be found in the basement or in a utility closet. Each individual breaker switch inside the box is connected to the wires going to specific rooms of the house. If there is a major energy-using appliance such as an electric water heater, it may have a single breaker switch devoted to it.
Old-style plug fuses contained a tiny strip of metal so thin it would melt away if too much electricity passed through it. The smaller the fuse amperage rating, the thinner the metal strip. The old screw-in fuses were risky because they were all the same size and homeowners were tempted to put in a stronger fuse than the circuit was designed for.
Modern circuit breaker switches work the same way, except that the switch is not damaged in the process. Instead of buying a new fuse, one only needs to reset the breaker.
How to reset a circuit breaker
Usually, when a breaker shuts itself off, the cause is apparent. Whatever appliance you just turned on before the outage is probably the one that overloaded the circuit.
Appliances can cause a sharp enough amperage spike to trip the breaker. Another common cause, which may be harder to identify, is when the air conditioner kicks on while you have other appliances running on the same circuit.
When the electricity suddenly goes out for only a portion of the house, this nearly always means a circuit breaker has tripped because of a surge in amperage required in the circuit. Before going to the breaker box, first turn off the appliances that were running in the rooms where the power has gone out.
Then take a flashlight and go examine the rows of breakers in the panel. It should be easy to spot the one that tripped because it will be out of line with the other switches. Turn it all the way off, then back on and wait to see if it stays on. If so, head back upstairs to see if the power is back on. Test it by turning the appliances back on.
What you should never do
In the days of screw-in plug fuses, people sometimes would replace a 15-amp with a 20-amp fuse in order to make it less prone to going out. This was a very dangerous practice because in increased the likelihood of an electrical fire. An even more dangerous practice was putting a penny in the fuse opening to bridge the contacts instead of a fuse. This meant the fuse would never go out, but left the house with zero protection against an electrical fire. Many homes burned down because of this.
Today, it's not so easy to circumvent the purpose of breaker settings. If you have a breaker that repeatedly trips, contact an electrician to diagnose the cause.
What is a GFCI outlet?
GFCI stands for "ground fault circuit interrupter," which is a standard outlet that also includes a built-in circuit breaker.
Electricity always seeks the easiest route to the ground, so the term "ground fault" means any time the electric current departs from its intended flow. Water conducts electricity more easily than wire, so if an outlet gets splashed with water, the current might change directions and follow the water to the ground, possibly going through you on the way.
This is why GFCI outlets are often installed in kitchens and bathrooms. As with all circuit breakers, the GFCI breaker is designed to instantly interrupt the flow of electricity in order to protect against electrical shock.
GFCI outlets look just like their traditional counterparts, except they have two small buttons at the center. One is labeled "test" and the other "reset."
Testing a GFCI:
GFCI outlets should be tested regularly to confirm they are working correctly. To test the outlet, plug in a lamp and push the test button. If it's working, the lamp will shut off and the red reset button will pop out slightly. Push the reset button back in and the lamp should come back on.
Hidden GFCI breakers
There are different types of GFCI mechanisms and some of them can also interrupt the power going to other outlets which are not themselves GFCI. So when an ordinary-looking outlet loses its power, one thing to do is to locate any nearby GFCI outlets (some may be in other rooms or even on another floor) which may be on the same circuit as the outage.
And don't forget that many appliances and even extension cords and Christmas light strands have little fuses or GFCI trips built into them. This is all for your safety, but can sometimes drive you crazy trying to find them.