Every house has several junction boxes: a fiberglass or metal box that holds the connections to several different lines of electricity running through the house. If you would like to add additional electrical wiring to your house, the junction box is often the best place to attach a new line.
Step 1: If you have the electrical plans for your house, a junction box is easily found. Simply look for capital letter “J”‘s along the lines that indicate the electrical wiring in your house. Each J marks the location of a junction box.
TIP: If you make any alterations to any junction boxes, or have an electrician redo or add wiring to your home, be sure to make note of it. The easiest way to do this is to use a piece of tracing paper over the existing plan. Trace the general outline of the house, then make marks indicating the changes on the tracing paper. Date the paper so you know when the alterations occurred. Keep the tracing paper rolled up with the electrical plans. If you have flat 11×17 plans, which are common in a modern house, use a binder clip to keep the plans, altered plans, and other papers for the house together.
Step 2: If the plans are not available, take a look in your attic. You should be able to locate several lines of conduit. Look for a place where it appears that they intersect: the junction box should be near there. Many are covered with insulation, so wear gloves, safety goggles, and a face mask for best results.
Step 3: If you can’t find the necessary junction box in your attic, check the basement as well. It is not uncommon to find several electrical junction boxes in an unfinished basement. Just follow the location of the electrical conduit until it intersects with another section of conduit.
Step 4: Look in other areas where the junction boxes may be exposed. These areas include crawl spaces, unfinished rooms, and unfinished walls.