When it comes to the name, ring main is a term which has been used for years and in all likelihood will continue to be used for many more to come, but it is in fact incorrect, it’s just easy to say! In short if you cannot correctly test whether the circuit you have is a ring main or a radial circuit then you should not, under any circumstances be working on it. The UK is the only country in the world to work with ring mains, or final ring circuits and without the correct testing equipment and knowledge of procedures it is impossible to tell the difference. The major difference between this type of consumer unit and the below type is that this one does not feature an RCD’s so in terms of it’s relevance today, is now considered a little old-hat! Now that you know exactly what elements make up a standard consumer unit and why they are needed it’s time to look at exactly how they are wired up and why this is done a particular way.

It is possible to extend a ring main if you need to. For help and information on how to do this, please see our extending a ring main project here. Cooker and Electric Shower Circuits This seems to suggest that moving forward, RCBO’s should be used for individual final circuits as opposed to RCD’s as the earth leakage across several appliances on the same RCD could be enough to tip the balance and cause nuisance tripping, especially where washing machines, dishwashers and the similar that can earth leak quite a bit, up to 5mA in some cases are featured. Consumer Unit with MCB and main double pole isolation switch Step 3 – Connect up Main Switch and RCD One of the most important jobs your electrician will (or should) do before starting such a job is to first ensure they test all of the existing circuits in the property to make sure they function correctly and have no issues. RCBO’s used in a consumer unit in place of RCD’s – Image courtesy of the BS7671 18th Edition Wiring Regulations High Integrity Consumer Unit / Three-way Split Consumer Unit

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Finally, for more help and information on staying safe when working around electricity, see our electrical safety project here. What is a Ring Main or Ring Final Circuit or Final Circuit? This consumer unit, like the RCBO version was mainly born out the nuisance tripping addition to the wiring regulations and in effect combines the best features of each of the other types of configuration. Ring circuits are normally fed with a 30 or 32 amp fuse or MCB, but if feed is supplied through a 4mm cable then the spurs could also be feed with 30 or 32 amp fuse or MCB. It’s also important to understand that RCD’s have a test button which creates a simulated earth leak with a resistor, and it is usually recommended that they are tested once a month to ensure they are operating correctly.

An RCD is a manually operated isolator switch, but it is also an automatic safety device that will trip and cut off as soon as it senses an earth fault, or indeed earth leakage. Once the safety side of the board is in place, the next items to be installed are the MCB’s, one for each required circuit. Obviously, when a consumer unit is being installed the power to your entire house is isolated so that everything can be connected up and tested before it put live for use!Aside form the Part P requirements, there are quite a few other rules that govern how a ring main is installed such as the type of cable that can be used, the total floor area the circuit covers, the total length of the circuit and whether it’ll be powering outdoor appliances, more on this below. Again, it entirely depends on your existing electrical layout as to how this is done, but your electrician will certainly know. This range of all metal enclosures are manufactured from steel and are compliant with the 17th Edition Wiring Regulations, Amendment 3. Enclosure kits are supplied complete with devices, DIN rail, neutral cable, neutral and earth terminals and a busbar. We would like to thank one of our forum members for answering this question in our busy electrical forum, more information can be found on testing circuits here.