You can also read a brief synopsis on the electrical guidelines and what they mean by visiting our Approved Document P project here. As we have stated in the how to wire section above, junction boxes must be fixed solidly to a firm, suitable surface and must be accessible! These rules are stipulated in the latest 18th 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. Step 3 – Connect Wires: Once all stripped, connect the same core wire from each length of cable to the same terminal in the junction box e.g. brown live to live, blue neutral to neutral and earths to earth (remember to add some earth sheath to the earth wires – this is a legal requirement!). Make sure you screw each terminal screw down nice and tight Electricity is dangerous, that’s a fact! We are all taught this from a very young age. When it comes to the electrics in your home, unless you know what you are doing or are a “competant person” then you should leave it well alone!

In this guide we take a look at junction boxes and how they are wired up and used, read on to find out more. Working With Electricity and Junction Boxes 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.Junction boxes are rated in amps to protect them, you and the circuit. Make sure you have the right box for the right job. A ring main ( more about ring mains can be found in our project here) and also a radial circuit ( more about radial circuits in our project here) will need a 30 amp junction box, whereas a lighting circuit (although you can buy 5amp junction boxes) will need a 20amp junction box. Step 1 – Isolate Power: Before you do anything at all, first isolate the power to the circuit you are working on! Installations with plain green sleeving on the earth wires will typically be approaching 40 years old and are likely to require replacement.

Most electrical boxes are either metal or plastic: Metal boxes are generally made of steel, while plastic boxes are either PVC or fiberglass. Weatherproof metal boxes for outdoor use are generally made of aluminum. The main reason for this change was to ensure that any cabling used from that point onwards would harmonise (be the same) as those used in Europe. When it comes to wiring up junction boxes, as you would expect, there are some quite strict rules on how they are wired, where they can be placed and how any cables should be secured. All of this is covered below. If you use a metal connector to attach armored cables, you must also use a plastic bushing to protect the conductors utilized by the connector. Armored cable tends to be used in commercial wiring rather than residential homes.Junction boxes come with either 3, 4, 5 or 6 terminals so work our which you will need to complete your project. The terminals are where the connections will be made by inserting the wire core from either side or the wiring run and then screwing the terminal close to create a safe electrical junction and join.

If the box has breakaway plastic tabs (most often found on boxes that will be nailed to the surface), push the tabs out by hand or with a screwdriver.Step 3 – Connect to Terminals: Once all stripped, connect each core wire to an individual terminal ensuring that each type of core is connected to the same from the other cable, e.g. a 3 brown lives in one terminal, all 3 blue neutrals in another terminal and all 3 earths in another terminal. Also ensure that you add earth sheath to each bare earth wire – This has to be done by law! All of the earth wires connect to the earth terminal, and must have green/yellow sleeving over them. Junction Boxes - end of line Choose a junction box with conductor fill volume (which is the number of conductors allowed in a junction box) higher or equal to the number of wires (after multiplying them by 2 and adding in the ground wire) entering the junction box. It’s best to choose a fill volume higher than the number of wires you have to ensure there will be enough room. [1] X Research source This section explains how to wire a traditional or standard style junction box. It doesn’t matter about the rating or number of terminals, the process is the same in each case. Joining Two Sections of Wire Together

To find the right size junction box in cubic inches, count the number of wires entering the junction box. Multiply the total by 2 when working with 14-gauge wire or by 2.25 when working with 12-gauge wire. Then, select the largest ground wire and add 2 if it is a 14-gauge wire to 2.25 if it is a 12-gauge wire. If you have ever needed to join 2 sections of cable or wire together or create an additional spur for a new piece of cable then you should be well aware of the existence of the junction box and if not, this is the product you want if you are needing to do either of these jobs.Internally, there are mounting points for screws in each corner, so you should use the correct masonry plugs, anchors and fixings for the surface you are mounting to such as a wall, skirting board or ceiling. Likewise, the cables running into and out of the junction box should also be secured to a suitable, stable surface. If not, then “mechanical strain” could take place and over time, wires may become loose causing loose connections.