It’s the control center for all the electrical service in your home, but how much do you really know about what it does? Here’s a quick look at the functions of that grey metal box, called a circuit breaker panel in the electric biz.
What is a Circuit Breaker Box?
The point where the power comes into your house is called the service entrance. It’s fed by heavy insulated aluminum wiring that runs from the utility provider’s transformer to your electric meter and into your circuit breaker panel. These wires can be overhead or underground and supply the total amount of power to your house. This is typically 150-200 amperes (amps) in newer construction but can range from 60-400 amps or more depending on the age of the home and its size.
A breaker panel (or box) is where the outside electrical power is distributed to the various parts of your house.
Where Do I Find My Breaker Box?
Indoor breaker boxes are often found in unfinished areas of the house—basements, utility rooms, etc. This allows easy access to the wiring that feeds the house and is especially convenient if you need to add new circuits.
But some homes, especially multifamily buildings like apartments and condos, will have the boxes set into a finished wall such as a hallway or utility room.
What’s in the Box?
When you open the door to the breaker box, you’ll see an array of circuit breaker switches with numbers stamped into them, typically from 15 to 40 or more. This tells you the capacity of the circuit controlled by that breaker. Lighting and wall outlets, called convenience outlets, have 15–20-amp 120-volt circuits. Larger circuits feeding things like stoves, ovens, and furnaces range from 30 amps upward and are often 240-volt, dedicated circuits, meaning they serve that appliance exclusively. There’s also a single breaker at the top of the panel that is the master switch for the entire panel. It’s there in case you need to cut off power to the whole house.
Circuit breakers come in three types: Standard, Ground Fault Circuit Interrupters (GFCI), and Arc Fault Circuit Interrupters (AFCI). Each protects against a particular type of fault in the circuit and each is specified by the National Electric Code (NEC) and local building codes, which should always be followed. That’s why it’s important that electrical work, especially around high-risk areas like electrical panels, be done by an experienced professional.
Finally, you may have secondary subpanels in areas like garages, shops, and outbuildings, or in parts of larger homes to add convenience and accessibility. They’re simply smaller versions of the larger main panel.
The Coverup
There’s a cover around the breakers and that’s as far as you should go into the box. Removed, all the wires feeding the breakers are exposed, including the main service, which is 240 volts and 100 amps or more…often a lot more. It’s there for your protection and should only be removed by a qualified electrician since if you touch the wrong thing, it could ruin your day—or your life.
Your Box Has a Split Personality
As we mentioned earlier, your main feed is 240 volts, but it’s split into two “legs” of 120 volts each. Depending on how the wiring is connected, the power can be rejoined to serve 240-volt circuits or kept separate for the 120-volt wiring.The breakers are connected to a common bus bar to supply the voltage needed for each circuit.
The circuit breakers are designed to turn off, or “trip,” whenever the load on the circuit exceeds its ability to conduct the current safely, either from an overload or a short circuit.120-volt circuits are protected by single, usually narrow, breakers. 240-volt circuits have two larger breakers that combine the lower voltage feed and are joined together to act as a single unit.
When a Breaker Trips
A tripped breaker is the sign of a problem. It can be as simple as plugging too many items into that circuit or it can be a sign of a bigger, more serious problem.
When a breaker trips, open the front panel of the box and look at how the various switches line up. Most will be in the “on” position, although a few may be at “off.” These are usually spare breakers or those on unused circuits. Tripped breakers snap to a middle spot that is neither on nor off and should be easy to spot.
To restore power, switch the breaker to “off” first. This resets it. Then flip it to “on” and wait a few seconds. If it trips again, locate the area it serves and unplug anything that might be causing it to trip before repeating the process again. If it trips again, try to locate whatever is causing the problem. If it continues to trip, leave it off until an electrician can identify the problem and fix it.
Note: In older homes with fuse boxes, people would sometimes replace a blown fuse with a copper penny to restore service. Chances are the fuse blew for a reason, and several of those who used a penny ended up standing outside and watching their house burn down.
Fuses and circuit breakers are there for a reason, soNEVER try to defeat their purpose.
Stay Safe with Professional Help
Doing electrical work safely requires a knowledge of electrical circuitry and codes. Don’t risk injury, shock, fire hazards, or expensive repairs by getting in over your head.
If you’re having any problems or concerns about your electrical service, or are thinking about remodeling or adding extra service like an electric vehicle charger, the pros at Allstar Electrical Services are ready to help. We offer homeowners, builders, and businesses reliable, professional electrical work that is safe and up to code.
Call Allstar Electricalat 303.399.7420 or visit our website. We’ve served Colorado’s Front Range for over 20 years, are top-rated by the BBB, and are an Angi’s® Home Advisor certified contractor.