Best method to wire conservatory

[Alphamike583]

Hi there. I'm scratching my head to determine the best option for wiring a new conservatory. Basically the customer wants 2 double sockets, 1 wall light and 1 external security light, with both lights connected to a double switch.
The easiest method for connection would be to the "kitchen ring". This circuit has three double sockets on and then a cooker, an extractor and a fridge all as fused spurs.

The main CU has no RCD but has 1 spare way.

Shall I

1. Extend ring circuit, through the 2 new sockets and then fuse spur to the lights (this won't have RCD protection though)
2. Install RCD fused spur for sockets then spur off of that circuit for the lights?
3. Install RCD fused spur for sockets then a fused spur for lights all taken from the ring main
4. Install 32a MCB in spare way in CU then run 4mm cable to a submain containing a RCD, a 32a mcb for sockets and a 6a mcb for lights?

Obviously looking for the cheapest and easiest route.
The sockets in the conservatory will run a washing machine and Freezer but it needs to be future proof in that there is a high likelihood a 3kw heater could be plugged in when they realise the conservatory is cold!

 

[Amp David]

Only you can determine the cheapest route as you have seen the job.

Option 1 isn't an option IMO as regs do not allow it.

Suggesting the future use of a 3kw heater also questions extending the existing kitchen ring. Also why would anybody want a washer and freezer in a conservatory?

 

[Richard Burns]

Install a 32A RCBO in the CU and run a 4mm radial out to the conservatory and use a 5A FCU to spur off for the lights.
You can't install without RCD protection (at least on the sockets), the kitchen ring is the most heavily loaded in a domestic dwelling (and assuming the cooker is not electric or it is very loaded) and so not a good idea to add to that loading.

If you use 4 then the 4mm submain run would need RCD protection or earthed sheathing.

 

[i=p/u]

or surface mounted should i add ..

im getting good at this stuff

 

[Alphamike583]

I had thought about RCBO but forgot to put that in my options list!!! I think I may go for this option. Just to double check, there is no problem with me having 2 fused spurs (one for each light) run in a radial fashion so it goes CU-socket-FCU-Socket-FCU. The FCU will be switched thus serving as the light switch and then run 1.5 mm cable for the light in case someone puts a 5a fuse in the FCU in the future, although it will be fitted with 3a.

The reason for going for the 2 Switched FCU's is because the customer doesn't really want a FCU visible unless it will double as a switch. The alternative is one FCU going to double switch and then to the 2 lights.

 

[i=p/u]

it can work as a switch but hey, nice tidy in line fcu beside socket , l,n.e to switch, then l,n,e to light, put in bigger back box if you have hands and fingers like a farmer rugby player

is that me stereotyping

 

[GLENNSPARK]

I had thought about RCBO but forgot to put that in my options list!!! I think I may go for this option. Just to double check, there is no problem with me having 2 fused spurs (one for each light) run in a radial fashion so it goes CU-socket-FCU-Socket-FCU. The FCU will be switched thus serving as the light switch and then run 1.5 mm cable for the light in case someone puts a 5a fuse in the FCU in the future, although it will be fitted with 3a.

The reason for going for the 2 Switched FCU's is because the customer doesn't really want a FCU visible unless it will double as a switch. The alternative is one FCU going to double switch and then to the 2 lights.

you think you may go for this option? i`d say its the only real cost effective option you have got.....so as richard burns....

 

[rich.250]

I had thought about RCBO but forgot to put that in my options list!!! I think I may go for this option. Just to double check, there is no problem with me having 2 fused spurs (one for each light) run in a radial fashion so it goes CU-socket-FCU-Socket-FCU. The FCU will be switched thus serving as the light switch and then run 1.5 mm cable for the light in case someone puts a 5a fuse in the FCU in the future, although it will be fitted with 3a.

The reason for going for the 2 Switched FCU's is because the customer doesn't really want a FCU visible unless it will double as a switch. The alternative is one FCU going to double switch and then to the 2 lights.

I would as I=p/u said. Have one un switched fcu. And feed the light switch from there.
This seems the best option to me.

Although I might possibly look at the loading on the kitchen ring, and if it's sufficient to add two so and two lts. It would extend the ring the fuse down the lights as this method and fit an rcbo to the circuit.

 

[Richard Burns]

I had thought about RCBO but forgot to put that in my options list!!! I think I may go for this option. Just to double check, there is no problem with me having 2 fused spurs (one for each light) run in a radial fashion so it goes CU-socket-FCU-Socket-FCU. The FCU will be switched thus serving as the light switch and then run 1.5 mm cable for the light in case someone puts a 5a fuse in the FCU in the future, although it will be fitted with 3a.

The reason for going for the 2 Switched FCU's is because the customer doesn't really want a FCU visible unless it will double as a switch. The alternative is one FCU going to double switch and then to the 2 lights.

I Agree with the above posts.
Running SO FCU SO FCU is fine for a radial (or ring) but will mean a lot of extra cable to wire the lights. 1.0mm2 can take 13A if in free air/plaster or in conduit.
If you are looking for the cheapest option then 1 FCU and 1 2 gang switch run in 1.0mm2 cable and feeding the switch will be the cheapest.