Why would installing a new circuit breaker be a needed task? Circuit breakers do go bad from time to time. The other scenario would be adding a circuit to your panel. Finally putting the media room in the basement? For whatever reason you will find that this is not that difficult. Your electric panel has more power coming into it than it needs. The circuit breakers control the amount of power that flows into various areas of your home.
Not sure if this is your problem? See the articles 'Troubleshooting Electrical Repairs', 'Fixing Residential Wiring' and 'Basic Wiring for Homeowners' for a complete listing of all the electrical topics.
Before you add a circuit breaker you need to make sure that you want to attempt this type of project. Working with an electrical panel can be dangerous and it may be impossible to completely turn the power off to the panel. There are also code and permit considerations. As a rule a permit would be required before you perform this type of change to your home.
Safety First
Electricity is dangerous and can injure or kill a person if precautions are not taken. Never work on any electrical device, wiring or panel without first shutting the power off.
See the article 'Residential Electrical Safety Tips' for some suggestions on how to shut down the power.
Reasons for Adding a Circuit Breaker
The wire and the electrical devices that you have in your home can only tolerate a certain level of power. Your original electrician has set up a sort of 'trust arrangement'. The breakers are sized for the wiring and loads that you have in a given circuit. He trusts that you won't overload that circuit. Installing a new circuit breaker would be the wise course of action, instead.
Generally a circuit is set up the use a maximum of 80% of a breaker's capacity. When you exceed 100% the breaker will trip as a safety feature. Kind of an electrical policing arrangement. Two causes for a breaker to trip repeatedly. One it has gone bad. The other is that you are overloading it. Either by too many devices or via a short. Read on to see if this repair is something that you want to try.
With that said, there are situations where adding a circuit breaker for a new circuit is not too difficult. You may want to add a few plugs to your basement for a work shop. Your panel has blank spaces in it and the floor joists are open to run the wires through. Even in this situation, it is a fairly big project.
Panel Size
You can do some checking on your own to see if your panel is large enough for an extra load. You can find electrical load calculators on line to help you with this. These will give you a general idea of whether your main breaker is maxed out.
Most panels are able to have a few extra circuits added to them. You can check the load for your panel by using a 'load calculator'. Follow this link, Single Family Dwelling - Electrical Load Calculator, to check your load. Do you have a hundred amp main breaker? Does the calculator say that you only need sixty five amps? Yes, then you can probably safely add another circuit or two. This will involve installing a new circuit breaker.
Local Codes
More issues here. You will probably need to check with your local building department. Permits may be required before beginning any electrical modifications. Yes, they will want fees. How do you think they pay for those cars with the funny license plates. Wiring for a new circuit is not discussed on this website. Sorry, you are into a home improvement subject. The installation of the breaker is similar, but the wiring is another subject.
Installing a New Circuit Breaker
A circuit breaker is very similar to a light switch. It interrupts the hot conductor or power conductor. The difference is that a circuit breaker has limits to the amount of power it allows to go through.
So you really only have two elements for the circuit breaker. The breaker and the slot it goes into. The other element is the hot wire(s) for the circuit. It's really not that simple, but it sounds good. I take that back. Installing a new circuit breaker in a replacement situation is that simple. One wire and the slot.
Almost every circuit has two other elements. The neutral wire and the ground wire. The neutral wire completes the path so the electrons have a loop to go through. Don't ask questions at this point, you won't understand the answers.
The last element is the ground. The ground is a safety feature. If the neutral ever fails the electricity will go to the ground before it goes through your body. Great feature in my opinion. You can liken it to a safety harness on an iron worker. Fifty stories up it is a hassle to put on a harness. As long as he does not slip the harness is never used. One slip and the harness saves his life. Well worth the hassle.
Before you begin installing a new circuit breaker, make sure the main breaker is off. The circuit breakers are friction fit into the panel. Generally you pull up on the side away from the center and they pop out. You hook them in the center, keeping them at an angle and press them into place. How easy is that? The breaker has a lug or lugs on it to hook up the hot wires.
For a single pole circuit it will usually be the black wire. Sometime a red wire if two circuits are being fed with a three conductor cable. Double pole breakers have two lugs. Sometimes a black and a red wire. Sometimes a black and a white. You put the hot wires in the lugs for the breaker. The neutral goes on the neutral bar (mostly white wires attached) and the ground goes into the ground bar (all bare copper wires attached).
See the articles 'Replacing Circuit Breakers', 'Basic Residential Wiring' and 'Troubleshooting Electrical Circuits' for additional information on this topic.
Summary
Installing a new circuit breaker without any of the related problems is not more than a ten minute job. The problem is that you need to determine if it is really the circuit breaker that is the problem. You may have checked things out and realized that you had eighteen items plugged into one outlet. Or you may have found a short. Your poor circuit breaker had been unjustly accused. Rarely, the breaker is the culprit and needs to be replaced.
Did you decide to add some things? Then installing a new circuit breaker is called for. You may have had a loose wire that was difficult to find. Some serious work. Take comfort in this, if it was hard for you, it would have been hard for someone you hired. What do you do now? Hopefully you have someone that will give you a little well earned praise. Bragging is an acceptable alternative.