Each MCB is installed by clipping it onto a DIN bar and the "teeth" of the bus bar are inserted into the base of each MCB. This carries the live current into the MCB and the cable that supplies the given circuit are connected to the top section. If this is a new consumer unit install for an existing property then your electrician will have either marked each circuit to identify what it powers or will work each one out as he gets to it. In terms of the law, RCD’s are only required to be installed in a new build, where additions or major alterations are done to an existing property or when a rewire is carried out. Choosing a suitable consumer unit for a job will depend on several factors. So, here are some important things to consider about the installation before you decide which one to buy: Again, it entirely depends on your existing electrical layout as to how this is done, but your electrician will certainly know.

The fact you keep saying "signed off" in quotes like you think I'm some have-a-go cowboy is pretty irritating. I'm asking questions on this forum, hoping for some advice, to try and do the job properly. One said to use SWA, the other said it could 'probably be done with electrical cable in conduit' but I forgot to ask specifics as I didn't realise there was so many options / sizes. Surely someone can tell me what an accepted and safe cable is based on the photos I've provided?

What are RCD’s?

Once all of the MCB’s have been connected up, the final job then is to simply connect the earth running from the meter to the earth bar in the consumer unit When it comes down to it, the only person(s) able to do this are those that are Part P registered. If however you ignore this and do carry out electrical work that you’re not allowed to, this is illegal and also can invalidate your home insurance and cause potential issues when trying to sell your home. What materials they are going to use, ie cable sizes, brand of accessories (ie not utter carp that will cause issues later). Often I will supply these to them as my price via the wholesaler is often a lot less than they could get in a DIY shed. More recently RCBO’s have since come onto the scene. These are essentially a combination of an MCB and RCD so provide additional safety levels. Also they resolve the nuisance tripping issue highlighted in subsequent versions of the Wiring Regulations.

so, unless YOU understand what all the options, sizes, installation requirements are that BS7671 needs, then you need the so-called electrician - who is going to put his parts on the line when he fraudulently signs the paperwork as saying he did the stuff - to tell you what where and how you do what he is taking on. When purchasing a consumer unit, it will either come with a main switch and RCD and possibly a number of MCB’s or it will come empty. Depending on how it’s being wired up and what your electrician has chosen to use will depend on what you go for. Will anything I'm doing need to meet certain regulations? It'll obviously need to be inspected and signed off but I'm mainly thinking about the 2m distance of cable, as I've seen similar posts where all sorts of numbers are being thrown around about distance vs regulations. The split board shown here has one RCD and is a simple version to show the user how the board works, however most modern split load boards feature 2 RCD’s. Despite this there remains many still in use in many homes across the UK today, however whether they are still legal very much depends.Is your electrician a member of a competent person scheme? (NICEIC, NAPIT etc). Did he agree to do the notification as well? Then there is another process called NOTIFICATION. This is needed for new circuits and consumer units and is carried out with your local friendly building control. In pretty much every other configuration they are a required feature for each and every individual circuit.