When the microwave and the toaster are on at the same time and the power goes out with a pop, it's time to go to the breaker box. Your home has an electrical panel, also known as a service panel, circuit breaker panel, or fuse box. This panel is where the electrical power enters your home and is then distributed to individual systems or circuits. As a homeowner, you need a basic understanding of how it works.
Introduction to Electrical Panels
The first thing you should know is that you should keep your hands, fingers and any body parts out of it. All panels have a door that can be opened to check for tripped breakers or blown fuses. This is safe. Removing any cover screws is not.
There is very little a homeowner can do by himself or herself when it comes to circuit panels. If you are experiencing problems not covered in this introduction, or smell smoke or see sparks, call an electrician.
Fuses vs.Circuit Breakers
Older panels normally used fuses that screwed into openings, similar to light bulbs. In most cases, it was easy to identify a blown fuse. You can often see a burnt mark or a small broken wire in the clear glass center. Always replace fuses with the same amp size. Never use a higher rated fuse; this can cause a fire.
Long, cylinder fuses are normally only used for outside disconnect panels for AC systems. These fuses are trickier to install and remove. You will also need an Ohm meter to test them to see if they have blown.
Today a tipical panel uses circuit breakers rather than fuses. Instead of burning out like a fuse, an overload causes a mechanical switch to flip - breaking the circuit. A tripped circuit breaker has a small handle that appears in the middle of the device. Some breakers also have a small red area that will appear when the circuit trips. You can reset tripped circuit breakers by flipping the switch portion all the way off and then back on. If a breaker continues to trip you have a larger problem and may require an electrician.
Older fuse style panels were often rated at no more than 60 amps. This is nowhere near enough to run a modern home. For the average smaller home, a 100-amp panel is normally recommended. Large homes or those with high electrical usage should have 150 to 200 amp panels.
What They Really Handle
Electrical circuits are listed at a maximum rating; this rating is not designed to handle a continuous load at the maximum. A circuit is designed to handle 80 percent of the load it is rated for. For example, a 20-amp circuit can handle a continuous draw of 16 amps or 80 percent. Circuits should never be loaded with more than this amount.
Your panel will have 15 and 20 amp breakers for lighting and power circuits. The panel will also have higher rated breakers for appliances like electric dryers or ovens and AC units.
How Much Power They Use
Standard circuits in your home normally do not present problems. Lighting circuits tend to have a constant load, increasing or decreasing as lights are turned on and off. Circuits that are handling appliances with motors can be the problem areas. When a refrigerator compressor or AC unit kicks on, the circuit experiences a sudden increase in draw.
Most lighting circuits are 15 amps. A 60-watt bulb running on 120 volts uses ½ amp. Therefore, one lighting circuit could run 30 60-watt bulbs, minus 20 percent or 24 bulbs. Switch to CFLs and you get even more.
The average coffee maker uses 900 watts. A microwave or toaster uses 1440 watts. A refrigerator, when cooling, uses up to 700 watts. When just running, the refrigerator uses about 150 watts. These numbers show how a busy family kitchen could easily overload a circuit in your panel.
What Makes Them Trip
Breakers trip or fuses blow for three reasons:
- The device, the breaker or fuse, could be defective
- The device connected to the circuit is defective, for example, a bad toaster
- The circuit is overloaded or the wiring is bad
A homeowner can make a simple, preliminary test. Reset the circuit breaker and see if it holds. If it continues to trip, unplug any appliances connected to it. Reset the breaker and then slowly start reconnecting appliances. In many cases, because of the increased use of power in kitchens or other rooms in a household, you may just have overloaded the circuit. For any other electrical issues, do consult an electrician.