planned conservatory wiring

[Damocles]

I agree, if you can manage it, it would be best to expand the ring to include all the new sockets. This is assuming the conservatory is a definite permanent and waterproof addition to the house. If there is any doubt about this it might be better to stay with just one spur coming in.

The first FCU must be BEFORE the existing spur socket in the existing room. Everything spurred must go after this first 13A fuse. You could put in the FCU either next to the existing socket (make a hole in the wall for the box on whichever side the cable enters and then go on with new cable), or next to the socket where the spur cable starts (if it starts somewhere else in the room at a different socket)

The second FCU would go where it is most convenient.

 

[brown-nought]

I agree with all the negative comments on the plan you originally suggested. So its on to plan B.

Part P requires you to give building notice, but that to one side, if the inspector is coming to assess other part of the work he will notice the wiring and will of course want to see that it complies. With Part P some jobs will slip under the radar but not if the inspector is already coming.

Extending the ring is the neatest solution. The lights can be run from a FCU with 5a fuse on the ring. . If you can access two adjacent sockets all you will need to do is to remove the cable between them and feed a new loop in starting at one socket and ending at the other. If you cannot reasonable access two sockets you can still split the ring by changing a double socket to two singles. One on the out leg and one on the return. Don’t extend the ring using junction boxes.

The main reg/inspection issues:-

1) Extend the ring in the same cable size (should normally be 2.5mm) and ensure the protective device is suitable (for a 2.5mm ring that’s a 32A MCB(or RCBO) Type B.)
2) Remove the old link between the in and out sockets otherwise you create a bridged ring which isn’t allowed
3) Only wire in permitted routes.
4) Fit the new conservatory sockets and switches between 450mm and 1200mm. (If you want different heights you may be allowed but ask the building inspector first).
5) Ensure that the sockets in the conservatory are protected by a 30ma RCD – they could be used to power outside equipment e.g. a garden mower.
6) Verify that your ring covers an area under a 100m squared.
7) Check you have continuity in the ring. I.e. the two legs of the L, N & E wires all are linked before you fit the final socket. (It will be tested by the electrical inspector)
8) The circuit is labelled at the Cu.
9) No unsheathed cables protrude from any fitting or back box. Use open grommets on metal back boxes where cables enter.
10) Bare earths wires are in green/yellow sheath and that switch cables are red/brown or marked with red/brown tape.

Have I missed anything??

 

[ban-all-sheds]

3a) Or use mechanical protection as per the regs.
3b) If the ring cable is grouped with others, or runs in insulation, verify that its capacity is OK.

7a) Check that your R1+R2 is OK, given the type of protective device and the type of supply, for a 0.4s disconnection time

8a) Place a permanent label near (not on) the CU if you've got mixed wiring colours.

 

[wemyss]

Some wonderful advice and all has been duly noted. Having assimilated all this I have decided to go down the following route.
There is a twin socket near the patio door which will lead out into the new conservatory. As suggested I will cut out and fix a FCU below this and then spur off from the twin into the conservatory in 2.5
In there will fit another FCU for the lighting and the ceiling fan and fused at 5A.
I presume a fan simply needs a 1.5 T&E.?
Fit steel capping over all exposed cable and label as necessary.
I’m fortunate in that we have a wooden suspended floor which was a godsend in installing my heating many years ago. But having been retired eight years I’m not so fond of crawling about under there trying to continue the ring into the conservatory even though I recognise from your comments it is the absolute ideal.
But after all its only going to supply 3 twin S/O used for table lamps etc and a wall lamp and fan.
I have a RCD in the garage from which all outside equipment such as garden equipment is used so will not fit one inside the conservatory.
I’m not aware of any inspection that will be made on completion. Planning permission had to be sought but conservatories at present (according to the conservatory man) do not have to conform to building regulations but are planned for next year.
As he rightly points out this is going to cause some waves in his business as the regs define that specific insulation values must be adhered to. However these can’t be attained in a conservatory which is after all mainly built out of glass.
wemyss

 

[Damocles]

I think the part P new building regs about wiring are specifically worded to include outbuildings, and I would presume conservatories. So beware, if building regs or planning are involved at all. Perhaps you might add the electrics after thay have all gone away?

I do remember conservatories being excluded from building regs, specifically as you say because they are meant to be a glorified greenhouse rather than a habitable room. I doubt this exemption applies to electrics.

I don't know what you mean to do about the existing outside light? Perhaps you might like to move it somewhere more convenient this year while there is no question about part P.

I would not argue with your reasoning about RCD protection. But I suspect an official inspector very well might. This could be solved by using an RCD fused spur before the first socket. Expensive though.

 

[ban-all-sheds]

This could be solved by using an RCD fused spur before the first socket. Expensive though.

£20-ish extra on the whole project?

Not going to break the bank, surely...