Electricity and Electrical (Basement Wiring)

If you are planning on finishing a basement or adding an addition to your home one of the requirements is to create a plan. The items and quantities will vary with each homeowners requirements. The most efficient way to start is to create a rough plan of the electrical requirements for the new space.
There is design software now available that is very easy for any individual to use to design and/or decorate new space.  It is relatively inexpensive and well worth the investment. From this rough plan you can create a list defining the electrical requirements for the finished basement or addition.  At this time do not concern yourself with switch locations or the exact locations of light fixtures or other electrical devices.
 
It is not necessary to know the exact amperage that you will need for each item.  As an example for each light bulb, use 1 amp.  One amp will allow for a 100 watt light bulb. If you are in doubt about the amperage needed for any specific electrical item you can usually find the wattage of the item with an online search.  If you know the watts (power consumed), you can determine the amperage by dividing the watts by 120.  As an example, an item that consumes 900 watts will require 7.5 amps.
 
Certain items should be powered from their own circuits and not be shared with other electrical items.  Appliances such as electric baseboard or radiant heaters, refrigerators, microwaves, dishwashers and washing machines should have their own 15 or preferably 20 amp circuits.  Of course, appliances such as ranges, cooktops, ovens, water heaters and laundry dryers require specialty high amperage circuits.
 
Once you know how many circuits you will need you must determine where you will obtain the power from.  In most cases, with a finished basement, the electrical service is in the basement area which usually makes it quite accessible.  If however, this is an addition, getting the electrical power to the new space could be a challenge.  A challenge that must be solved.  As the possible situations are endless it is impossible to tell you how to get from point A to B.  That being said, some considerations include, running a conduit underground from one side of the house to the addition, going up through attic space and then down again.  I can almost assure you that there is a way to get from point A to B - you just have to be creative and it may not be the shortest distance! In our example we know we need 4 new 15 amp circuits to provide the necessary electrical services for out finished basement or addition.  We know have to look at the electrical distribution panel (load center), to see if we have the necessary free breaker positions.
Your home electrical distribution service is made up of one or more electrical breaker panels, called distribution panels or load centers.  Each breaker represents a separate circuit.  If your electrical panel looked like the picture on the right, you would have 7 free spots for additional circuit breakers.  This is not always the case.  Many electrical panels are filled with breakers requiring you to add a sub-panel in order to have more breaker positions.

The best way to add a sub-panel is to feed it from a double breaker in the main distribution panel (load center) which if the main panel is full, would require moving 2 of the current circuits to the sub-panel, opening up a space for the new double breaker.
 
Selection of sub panels
 
We have determined that we have enough free spots in our main electrical distribution panel to add the 4 circuit breakers required. The next stage in the exercise is to take our original draft layout and refine the drawing by adding additional wall electrical outlets (receptacles) and determining which items will operate from which of the 4 circuits. I find it much easier to use colored circles to define each of the different circuits.  At this time it is also wise to add the electrical switch locations into the drawing to ensure that you do not try to control 2 circuits with one switch.
How the wires are actually run from the distribution panel (load center) to the individual electrical devices and from one electrical device to another is determined by the location of the distribution panel and obstacles and obstructions between the panel and devices. When commencing the electrical installation start with installing all the electrical boxes in their appropriate positions.  Then run the wires.  Install the breakers after all the wires have been terminated.
 
Installing the electrical boxes and running the wires is called the "rough-in" portion of the electrical project.  The rough-in is done prior to installing any finishing materials such as drywall and acoustic ceilings. Installing the devices such as electrical switches, outlets (receptacles), cover plates, and light fixtures is termed the "trim-out" and is usually done towards the end of the project, after painting.
 
The preceding home improvement article was contributed by Renovation Headquarters, owned and operated by Bill Prudehome. With more than 25 years in senior positions in the construction industry, Bill has been providing home renovation, home remodel and repair services to individuals and small business throughout North America.