Junction box how does it work

Junction boxes are helpful for wire splices because they also allow one to easily locate the wire splice area. Guides Share:. Select From Over , Industrial Suppliers. Receive Daily Industry Updates. Search Over 6 Million Products.

An electrical junction box is a prime member of the electrical wiring network used at houses and buildings. The plastic or metal boxes shelter the electrical connections of a structure maintaining safety. A junction box has two defined sizes-. A three-wire box i.

Wire box for five or more wires measures 2 by 3 inches with a depth of 3. Now that you know, how a junction box is defined; let us talk about what it is used for. A junction box acts as the summit, where the electrical wires connect before continuing their path.

These boxes have different colors of wires portraying different elements. Such as black for heat, white as a neutral channel, and copper or green wire for grounding the connection. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Warning Since it can sometimes be a guessing game to figure out which breaker switch controls the room you're working on and often several different branch circuits feed through a single junction box, it's best to turn off the main breaker.

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The cables should be stripped to reveal the cable cores, but ensure that you do not do this back beyond the junction box itself. The cable leaving the junction box should be complete and intact. The cable cores will need to be stripped before being inserted into the terminals. Try to expose the minimum amount of the conductor as necessary.

UK wiring colours went through a change in March The traditional red live and black neutral were changed to brown live and blue neutral. The earth wire remains as yellow and green if sheathed but it can also come bare. As stated above, if bare, you should cover with some sleeve just to indicate that it is the earth.

For more information, please also see our project on the New Wiring and Cable Colours for a full explanation about the cable colours in use. Junction boxes must be fixed solidly to a firm, suitable surface and must be accessible. These rules are stipulated in the 17th edition regulations and must be adhered to. Screw the base of the junction box to a joist or rafter through the securing holes indicated in the image below.

This does not necessarily mean they have to be visible, they can be fixed in floor or roof voids. Accessible means that a builder or electrician can easily remove part of the floor or ceiling etc…. Junction boxes may not be buried in plaster or other similar materials. Likewise, the cables running into and out of the junction box should also be secured to a suitable, stable surface.

Cables should be clamped using cable clips or clamps. Please also check the rules very carefully for ring mains and radial circuits. You are limited in the length of cable you are allowed to use in both circuits and long spurs could make you exceed the limit and over load the circuit! If this is the case you are asking the circuit to use much more energy than the circuit is designed for. For detailed information on the rules and for more specialist advice please download the latest Approved Document P available from the Planning Portal website.

You can also read a brief synopsis on the electrical guidelines and what they mean by visiting our Approved Document P project here. Once the junction box has been fixed to a secure surface, and the wiring has been connected to the terminals and tested you can close the junction box, they must never be left open and exposed. The cover is screwed closed using the provided securing screw or possibly screws through the cover and fixing it to the base.

It is often necessary to adjust the wiring inside the junction box to allow the cover to close. Avoid simply forcing the cover closed with the screw as this can risk causing damage to cables.