This is My Old House. My wife and I recently bought a home, built in 1900 in a small rural town. The last 2 decades have not been kind to her. We are now attempting to breathe life back into this shell of a home.
Over the next few weeks, I will be providing you with several articles that will chronicle the various projects we take on as we work to refurbish my old house.
This series of articles will concentrate on the task at hand and assume you have already acquired all the needed permits and inspections. Also, I have been a DIYer for more than 30 years so I am comfortable with many aspects of home remodeling and repair. If you don’t understand any aspect of the projects to come, then you should not attempt them on your own. Getting in over your head on a project can cause damage, cost you money and even injure or kill someone.
In some home renovations or remodeling projects, the installation of an additional electrical circuit may be needed. This could also be true if you are adding a new appliance that draws a lot of power or will need its own circuit. In either case, installing a new circuit breaker is a pretty simple process.
Before I go any further, let me warn you. You will be working with an electrical service that is designed to deliver enough electricity to seriously injure or kill if you come into contact with it. So, safety is key in doing this job. If you are not comfortable with working with electricity, you should not attempt this project and hire a professional electrician.
The first thing you need to know before attempting to install a circuit breaker is what voltage and amperage you will need. The 2 normal voltages found in most homes is 120v and 240v (though most people commonly refer to these voltages as 110 and 220 respectively). If you are installing a circuit that will operate lighting and normal wall outlets, you will be installing a 120v circuit breaker. If you are installing an appliance that has a heavy draw like an AC unit or an electric water heater, you will likely be installing a 240v breaker. The best way to tell if an appliance is 120v or 240v is to count the wires. If there are 2 insulated and 1 bare wires it is likely 120v. If there are 3 insulated wires and a bare wire it is 240v. To be sure, check with the manufacturer. You don’t want to connect a 120v appliance to a 240v circuit, lest the appliance will be no more.
Next you need to know the amperage required to operate the circuit properly. This is pretty easy to do if you are just installing a single appliance to a single circuit. A handy little equation I picked up along they way will help you get pretty accurate as to the amperage needed for a circuit. Determine what the wattage of the appliance is, then divide that by the voltage then multiply that number by 1.25 and you have a good estimate of the amps this appliance will pull.
Example: Appliance rated at 4,000 watts and operates on 240v.
4,000 divided by 240 = 16.66 x 1.25 = 20.83 amps
It becomes a bit more complicated if there are multiple draws on the circuit. Say you have a room with lights and wall outlets. Start with the lighting. Using the calculation I showed you, the average 60-watt light bulb uses a little less than ¾ of an amp. Record the amperage for each light you expect to install or plug into the room. Now, you need to do a fortune telling and determine what other items you will be plugging in to the room, use the same calculation and record your results. Now add up all the amperage requirements and this will be a fair estimate of your needs.
When selecting the circuit breaker for your specific needs, make sure you go sufficiently above your amperage requirements, without going to far over. For instance, in the example above of a 20.83 amp requirement, a 30-amp 240v breaker would be adequate. For a single room with lighting and wall outlets, a 20-amp 120v circuit breaker will usually do the trick, but calculate your specific needs to be sure. Also, when you go to look at circuit breakers at your local hardware store, you will notice a difference in the physical size of a 240v and a 120v circuit breaker. The 240v breaker will look basically like 2 120v breakers stuck together.
With your breaker selected you can begin the installation. 120v and 240v breakers are connected and installed pretty much the same way. We are going to assume here that you have already fished all your wire and made the rest of your connections and you are now left to install the breaker. You need to also make sure that power has been cut to the terminals on the breaker box. I personally turn off both the main breaker in my breaker box, as well as the breaker main that sits next the meter outside. However you do it, make sure it is dead. Use a voltage meter to be sure. You definitely don’t want to be messing with live wires! The wire you are installing should consist of one bare wire, the ground, one white wire, the neutral and one black wire, the hot wire. If you are installing a 240v circuit, there will be two black hot wires.
Install the bare ground wire first by sliding the end behind one of the small lugs of the ground bus bar in the breaker box and screwing the lug tightly onto the wire. Next, strip ¾ from the end of the white neutral wire and insert it behind a small lug on the neutral bus bar and screw it down tight. Now strip ¾ of an inch from the black wire(s). On one edge of the breaker will be a screw. Loosen the screw enough to slide the wire under it and tighten it. If you are installing a 240v circuit breaker, there will be 2 separate screws to accommodate the 2 black hot wires.
Now that all the wire are hooked up, install the breaker by inserting the groove on the back of the breaker onto the lip on the outside edge of the panel, then rock the breaker forward so that it makes connection and seats properly onto the connection strip in the center of the panel. If it is snug and doesn’t wiggle around, it is installed properly.
That’s it! Flip on the breakers and enjoy the power of knowing you did it yourself.
