A junction box is simply an electrical box that is firmly fastened to house frame or another structure and houses the connection (splice) of two or more circuit wires. Junction box covers must be accessible; they cannot be concealed under drywall or other surface material. A special cover is used for ground-fault interrupting circuits (GFCI). Junction boxes are required by law in some states for connections between the exterior and interior wiring systems. In other states, only metal boxes attached to the wall with screws are permitted.
Electricians install junction boxes either before or after installing the drywall. If the box is installed before the wall is put up, it needs to be deep enough to accommodate the wiring passed through it. The electrician should also check all walls for any obstacles that may prevent him from installing junction boxes there. For example, if there's no room for a junction box behind a radiator, he will need to run additional wiring to an available spot. Radiators that are open on one side only can sometimes be fitted with a junction box, allowing you to connect them into existing wiring. This is called radiating the line and is allowed under most building codes. Junction boxes are designed to handle current surges caused by lightening strikes or other causes. So long as you follow proper safety procedures when working with electricity, you should have no problem installing a junction box.
There are several types of junction boxes.
A junction box, also known as a splice box or switch box, is an electrical enclosure that houses wire within your home. Electrical lines flow behind your home's walls and through the ceiling, meeting at junction boxes. Completely burying a junction box in a wall is a safety issue. If you were to hit a pipe or other object with your car and cause an accident, the box would help contain any damage caused by an electrical surge.
Junction boxes are used for wiring appliances such as washers, dryers, and ranges. They can also be used for connecting multiple circuits together. For example, two separate circuits may run into one junction box, then out again through separate outlets on the box. This allows you to combine several circuits into one area without having to break up your wiring system. Junction boxes are also used where changes in direction of power are needed; for example, when turning a corner in an apartment building. A junction box can be used to connect two sets of wires together so they can be routed along different paths within the building.
Junction boxes are available in various sizes and styles depending on the needs of your project. Some common options include concealed-type boxes, which are completely hidden from view inside the wall; semi-concealed boxes, which have a decorative cover but are still visible from outside the wall; and exposed-type boxes, which are not covered and are therefore more functional.
When an electrical circuit branches out in two or more directions from a site where an outlet or fixture is not practicable, a junction box is most typically employed. The box provides a convenient location for dividing up wires that would otherwise have to be separated at each end of their run. Junction boxes come in several sizes and styles. The cover should match the size and style of the box itself. A simple way to conceal unsightly junction boxes is with custom-made plasterboard panels. These can be painted if desired, but only hardwood flooring or tile will not be damaged by paint.
The covering should be flat and smooth. It should not have holes because those areas could act as locations for water to collect. If the cover has any sharp edges, they could cut into your hand when you touch them. Always wear rubber gloves when working with junction boxes.
There are three main types of junction boxes: metal, plastic, and wooden. Metal boxes are usually best left exposed unless you want to add extra protection against corrosion for things like power cables. Plastic boxes are used mostly for split circuits (where one part of the house has all copper wiring while another part uses only black and white wires) and are available in different colors to help you identify which parts of the house are connected to each branch of the circuit.