Understanding Circuit Breakers

Most home owners have been there....standing in front of a metal box in the basement, flashlight in one hand, either trying to flick switches back and forth until the lights come back on or scared to touch anything for fear of being electrocuted or setting the house on fire.....

But it doesn't have to be that way. A basic understanding of the electricity in your home, the service panel, and circuit breaker, and you can easily see which circuits are tripped and if you can get the lights back on yourself or you need to call in the professionals.

What is Voltage? What is an AMP?

In the most simplistic of terms, voltage is the force of the electrical current. In the US, houses typically have circuits that accept 120 volts. Amperage or amp is the strength of the electrical current required to operate a given device.

How Stuff Works has a great primer on Volts, amps, watts, and ohms that I highly recommend.

How Does Electricity Get Into My House?

Electricity is created in generators at power plants. The current created is then processed through transformers which increases the voltage. This increase helps to propel the current long distances through the high-voltage transmission lines. 

Substations in your neighborhood accept the high-voltage current and lower it so that the current can safely travel down smaller, local power lines. Transformers on the power lines lower the voltage even more and ultimately deliver the safe voltage to the "service drop" on the outside of the house that includes the meter. 

The current passes through the meter and into the "service panel" which includes the circuit breaker or in older houses, the fuse box.

What Does the Service Panel Do?

The service panel is essentially the distribution hub for electricity in your home. Unless a particular appliance needs it's own circuit (dryers, electric stoves, water heaters, air conditioners, etc.), most circuits control multiple outlets. All of the outlets or appliances controlled by a particular circuit is called a circuit branch. 

The circuit branch distributes electricity to outlets and light fixtures on its branch. So, as an example, all of the outlets and lighting fixtures in your bedroom may be on the same branch. When you plug in too many appliances, all of the outlets and light fixtures in that room stop working. 

What Does the Circuit Breaker Do?

The circuit breaker is essentially a safety gatekeeper that prevents an electrical overload by breaking the current if too much electricity is being drawn through a particular circuit branch. Except in the instances where an appliance is on a designated circuit, outlets share the amount of amps that are safely able to travel through a circuit branch. So, too many appliances drawing too much current through a circuit branch will cause the circuit to "trip" or break and halt the flow of electricity to everything on that branch.  

The circuit breaker has rows of labeled switches that designate which room or appliance a particular switch controls. When working properly all of the switches are all in the "ON" position. This means that the power is "on" and flowing properly through those circuits and through the related circuit branch. 

When the circuit is tripped, the circuit for that particular branch flips to the "OFF" position.

So I have tripped a circuit. Now What?

Look outside. Are other houses also without electricity? Many people rush to assume that the power is off in their house and start fiddling with the circuit breaker or calling the electrician when the problem is outside of their control.

If it is a problem specific to your home, you want to get the power flowing to the area of the house that has been cut off. Unplug whatever appliance you added to the circuit branch that caused the trip. Then go to the circuit breaker (usually in the basement or utility room) and find the corresponding switch. It should be in the "OFF" position, switch it back to "ON" and the power should resume in that area of the house. If you have a fuse box, you will have to replace the fuse. Generally this is as simple as removing the blown fuse and inserting a new one.

Don't go and plug the offending appliance back in or you will trip the circuit again. Instead turn off some of the other appliances on that circuit branch or plus the appliance into an outlet on a branch with less load. 

I keep tripping the circuit but I can't find the source of the problem. 

This calls for a bit of detective work. Is the circuit tripping when you plug in a particular appliance or combination of appliances? If you try to use the microwave and the vacuum cleaner at the same time, it might be as simple as waiting until your "Hot Pocket" is done to start the cleaning. 

If you don't have an obvious culprit, its time to call a professional electrician. Frequent trips are usually caused by1.   Overheating or faulty appliances
2.   Short circuits within your home's electrical system

Both can cause an electrical fire. 

Safety Tips

1.   Keep a flashlight close to the service panel. 

2.   If the switches on your circuit breaker are not labeled, consider having an electrician map your system. It will save you a lot of time and money if you and or an electrician can quickly identify a future problem, without having to figure out which outlet or appliance corresponds with which circuit.

3. Keep an eye out for scorched or yellowing outlets. This often means a short circuit in the system or touching wires behind the outlet panel. If you see this or smell burning, call an electrician right away.

4. Your outlets, circuit breaker, or service panel should NOT be making a sound, if it is call an electrician right away.

5. NEVER try to remove the panel behind the circuit breakers or use a screwdriver on anything in the service panel. That is an excellent way to electrocute yourself.