Installing an electrical box is a precursor to adding any device, like a switch or receptacle, to a circuit. Boxes can be made of metal or plastic, and you usually screw or nail them to a stud or rafter, although you can anchor remodeling boxes directly to the surface of drywall. The only difference between a box for a circuit device and a junction box, or J-box, is that the latter serves no other purpose than to enclose spliced wires. Its opening is covered, not by a circuit device, but by a flat metal cover.
Electricians usually minimize the number of junction boxes needed for wiring. They plan the circuitry so that they can make connections for branch circuits inside a switch or receptacle box, using a box big enough to accommodate all the wires. Careful planning usually eliminates the need for a separate J-box when wiring a room from scratch, but one or more may be necessary when adding to existing wiring.
A J-box may also become necessary in other circumstances, such as when a miscalculation results in the need for splicing because of a cable that is too short to reach its destination. When upgrading the wiring for a room, you may find it necessary to tap into a wire to add a branch circuit for a light or outlet. You should install the box with the opening facing out from the wall so all the wires inside are accessible.
Other boxes are used for hanging ceiling fixtures and other uses. Some boxes are made specifically for new construction, and others are made for retrofit work.
There are many types of electrical junction boxes available, and you can see many of them at any home supply store. Whether you want a new outlet added to your kitchen, a ceiling fan installed where there is none currently, or a new dedicated circuit added to your garage, a junction box of some kind will be needed.
Although there are some handy homeowners who are competent to do this work themselves, for most people we recommend having a licensed electrician do that type of work for you.
It can be dangerous at the time you are adding it, and it can be dangerous later if it causes an electrical fire. After more than 40 years of service, Frye Electric is a respected name with a respected reputation. Be sure which type of junction box should be used for ring main, radial circuits and lighting circuits.
Also includes safety tips and information on fixing junction boxes and ensuring they are accessible. Don't want to do this job yourself? Let us help you find a tradesman local to you. Warning: To complete electrical works you must comply with Electrical Regulations — Click here for more information. Part P of the new building regulations could involve a check on any additional circuitry by qualified electricians when you sell your home.
This can affect your sale, you could be breaking the law and your house insurance may not be valid. Please be absolutely sure you know what you are doing and get all of your work checked by a qualified electrician. Make sure you turn all power off and isolate the circuits you are working on.
Junction boxes can be used to connect additional sockets to circuits, add lighting points, extend circuits, and in general they are a way of getting power from an existing source and taking it somewhere else. They can also be used for repairs. If a wire has become damaged, the damaged section can be cut out and teh two sections joined back together again using a junction box.
In short they are used for joining wires or running a spur from an electrical circuit safely. Whenever you need to join two or more electrical wires, then you should use a junction box. As a result they are commonly used and very useful for anyone involved in wiring and electrics. You might be thinking that block connectors do the same job and you would be right, but they do leave quite large sections of wiring exposed and if you have removed long lengths of the protective sleeve from wires, bare live wires can be easily accessible and cause an obvious danger.
Junction boxes have an advantage here in that all wiring and joins are housed within the junction box itself, leaving no exposed bare wires that can be touched or knocked.
Junction boxes can also be used to add lights and switches. For more information please see our lights and switches project. A typical junction box — These can be purchased from our online store here. Electrical junction boxes come in a range of different types. There are two key differences that you will need to look out for when purchasing your junction box:. There are also different styles of junction boxes that you can use.
Each will differ slightly depending manufacturer terminal layout, slightly different mouldings etc…. We will explain the differences between these types of junction box and their various benefits shortly, however it is important that you have the right rating whichever type that you choose. Junction boxes are rated in amps to protect them, you and the circuit. Some metal junction boxes can support light fixtures; plastic junction boxes cannot withstand this weight.
Additional differences include installation, in that plastic junction boxes are typically quicker and easier to install than metal ones. However, a standard junction box designed to simple cover wire splices can be either metal or plastic. All wire splices must be contained within a junction box for a building to meet electric code , although sometimes splices are missed and may present hazards as a result.
Any exposed wiring can be dangerous, but exposed wire splices are especially prone to accident because they can be tripped over, expel sparks or misrepresent themselves be misperceived as playthings by children or pets.
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