Odd house wiring and CU replacement

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Some time ago I posted here inquiring about moving a CU in a cupboard away from the central heating boiler to make access easier e.t.c:

//www.diynot.com/forums/viewtopic.php?t=48642&highlight=

I haven't as yet done this but have recently been converting the surface mounted wall sockets to flush wall sockets in one of the rooms.

While doing this and turning off power to the plugs I noticed the wiring of the ring mains in the house seems to be odd if not incorrect.

The CU is an old bakerlite one that I swapped the old cartridge fuses for circuit breakers of the same rating as the fuses previous fuses. The CU has 6 breakers

6 - Upstairs lighting - 5 Amp
5 - Downstairs lighting - 5 Amp

4 - 20 Amp - Spur to what used to be Immersion heater.
3 - 20 Amp - All wall sockets in house on one ring main

2 -30 Amp - Spur to Electric cooker point - 3 sockets for gas cooker and washing machine run off this.
1 -30 Amp - Not used.

The lighting is as I would expect but it seems odd that the all the wall sockets except for the ones for washing machine and cooker are all on one ring main and breaker.

I was thinking while having an electriction replace and relocate the CU it would be a good idea to sort out the odd wiring to something like:

6 - Upstairs lighting - 5 Amp
5 - Downstairs lighting - 5 Amp

4 - Upstairs ring main (Not sure of rating????)
3 - Downstairs ring main

1 - ? - Connection to Shed in garden (Not sure of rating????)

The existing wiring in the house is grey sheathed with black and red wires and appears to be in good condition. My questions are:

1. Is the single ring main setup for all wall plugs odd or incorrect?

2.Would the connection for the shed just be on another circuit breaker?

3. I am intending on having an extension built on the back of the house in the near future. Would this just be done by breaking into the existing dowstairs ring main or do I need to consider this when having this work done e.g. an extra breaker?

4. The socket that used to run the ring main appears to only have one wire running back to the CU rather than two, is this just a spur direct of the CU?
As this cable is not used and runs from upstairs to CU could this be used when splitting the upstairs and downstairs ring mains. I am guessing there is another cable from the existing ring main running downstairs which could be used as other part of upstairs ring main?


5. How much of a job is it to separate the one single ring main for both upstairs and downstairs into two separate ones?
Is it a case of finding the first and last socket upstairs and running cable downstairs to CU?

6. I know this is obviously not a DIY job (I am not electrician and I guess this is Part P stuff?) but I would like to keep the costs down where possible. If anyone has any suggestions, for example could I run the cables from the various points (through walls e.t.c so that electrician can simply connect them up?

It did cross my mind that this is fast approaching a complete rewire of the house :eek: Ideally I would like to be able to keep the existing wiring with some alteration to change it as above, but I am not sure if this is feasible.

I can obviously ask the electrician who does this these questions but it would be good to get an opinion from people here so I have some idea of whats involved.

Thanks
Martin
 
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To properly answer this one would need a good look at the whole system. It is not unusual in older installations to have this arrangement (and yours could be getting on for 40 years old!). The sockets cct could well be a radial and not a ring, this would explain the 20Amp fuse and the single wire to the fuse holder. Changing to an upstairs downstairs split could be impossible without a rewire as, in the old days :) we used to wire up and down and not just left to right, so the cable may zigzag between the 2 floors. I am not sure what you mean by
the socket that used to run the ring main
though.

The shed cct would need to be RCD protected if you are installinmg sockets in it.

From your description I would, quite honestly, advise you to build the extension and have the whole place rewired at the extension first fix stage.
 

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