Rewiring options

[GowerOsprey]

Hi all

I am in the process of planning (i.e. I won't be installing it, but I'm trying to figure out what I want and where!) the rewiring of my kitchen, since knocking down a wall to combine our kitchen with the dining room.

Current situation:
The builder left me with a thick cable coming from a rose(?), replacing an identical one, which is currently connected to the hob; he did this to allow us to continue using the kitchen whilst waiting for our units and new appliances.
The oven has a three-pin plug which we connect to a socket that was originally in the dining room.
There is an external light which has a three-pin plug which I also plug into this socket.

My future (proposed) situation:
I would like to connect the new oven and hob, as well as the external light, to switched FSUs.
I am also having underfloor heating.

The Issue:
I was intending to use the redundant immersion heater circuit to power the U/floor heating, but this would require a lot of fiddly work to get the outlet from upstairs (outside the bathroom) to a suitable position in the kitchen-diner.

A friend (an engineer with a large white-goods company) who supplied my new oven and induction hob says that they can be powered through a normal 13A socket; I had thought of running a spur from the current double socket for this purpose. This would mean that the current hob cable would become redundant.

Can I therefore use this for the u/floor heating? Do I need to use thinner cable, or simply change the mcb in the fuse box? Or both?

Could I even power the hob, oven and u/floor heating from this one cable?

Hope this make sense and someone is able to advise!

 

[PrenticeBoyofDerry]

If you are having new kitchen installed, I would redesign your installation.
It would be hard to say what you could do or what you cannot with your existing set up. Only that it sounds like you are already asking for a high load to be taken from one socket-outlet that could well already be a spur.
Ideal situation independent circuits for hob, oven and UFH.
You also need to consider under worktop appliance and above worktop appliances.
Do you have RCD protection at the consumer unit/fuse board?

 

[EFLImpudence]

Hope this make sense

I'm afraid it doesn't.

The hob will need its own circuit to which you may as well connect the oven as well.
Would this be the thick cable? Roses are on the ceiling for light fittings.
Proper kitchen hobs cannot be plugged in

The UFH can be spurred from a socket or wired from the consumer unit at the most convenient position.

 

[GowerOsprey]

Okay, I'll try to explain it more clearly (I hope!):

At the moment, I have:
- A double socket, into which I plug my oven and outside light. I believe that this is a part of the downstairs ring main, not a spur.
- A thick cable coming out of one of these [http://www.screwfix.com/p/crabtree-4-terminal-20a-junction-box/70677]. There is one cable going into it and one coming out, which is connected to the hob. This has not been chased yet.

I need:
- An additional double socket, about 1m away from the current double socket
- One of these [http://www.screwfix.com/p/crabtree-45a-dp-sw-neon/98632] for the oven
- Same again for the hob
(EFL, your post suggests these could both come from the same, thick cable; but would they need separate switches?)
- One of these [http://www.screwfix.com/p/lap-13a-switched-fused-connection-unit-white/29377] for the outside light
- Another connection for an RCD for underfloor heating.

PrenticeBoy, I would love to be able to start over again but am limited by funds and the circumstances of the room and current circuit layout. Not sure if I have RCD protection for fuse board, what would I be looking for to check?

So, if the oven and hob are connected via the thick cable, can I also get a spur from this for the new double socket?
I could then spur from the existing double socket for the UFH?

 

[PrenticeBoyofDerry]

RCD

Untitled

• PrenticeBoyofDerry
• 29 Jul 2009
• 5

Have a test button on. Likely to say 30mA

The thick cable does sound like it is provision for a cooker circuit, you could indeed have both hob and oven connected to this, will need a little additional work for independent isolation.
If funds are restricted and you intend to keep work to a minimum but still want a well designed, functional circuit, instead of spurring from ring final circuit, extend it, so it is still kept to a full ring.
But you are going to need RCD protection, the current requirements state it>

 

[GowerOsprey]

Yeah, my consumer unit has one of those.

Could I ask a dumb question (or three!)?
Does a spur only have one cable going in (or out) of the pattress/mounting box?
If its part of a ring main, will it have two cables, one in and one out?
If I extend the circuit as you recommend, do I just run a cable from the existing socket to the new socket, then another cable back to the second cable in the first socket?

 

[EFLImpudence]

Does a spur only have one cable going in (or out) of the pattress/mounting box?

Yes, the end of a spur will.

If its part of a ring main, will it have two cables, one in and one out?

Yes, but so does a radial (except the last one).
So you can't tell if the circuit is a ring or a radial by looking.
Where the spur starts on a ring or a radial there will be three cables

If I extend the circuit as you recommend, do I just run a cable from the existing socket to the new socket, then another cable back to the second cable in the first socket?

Yes, but not really much point for a short spur to one socket.

 

[PrenticeBoyofDerry]

Yeah, my consumer unit has one of those.

Could I ask a dumb question (or three!)?

never a dumb question, often dumb not to ask them!

Does a spur only have one cable going in (or out) of the pattress/mounting box?

If a spur was taken from a RFC (or a radila circuit), then you would have three sets of grey sheathed cables. Two would be from the ring and the third would be the spur. If it was a fused spur it would have a supply in and a load out, so two sets. If it was the end outlet on a spur it would only have one cable, this is also true if it were the end socket on a radial circuit also.

If its part of a ring main, will it have two cables, one in and one out?

Not necessarily, RFC and radials will both have two sets of cables in them, unless it is the end outlet of the radial. If you look at your consumer, is the circuit labelled up or do you have documentation of installation.
If not one way which may help is by removing cover of CU (isolate first)
and the RFC generally have two red or brown going to the MCB/Fuse, this would be normally 32A, it is not an absolute certainty that it is a RFC but normally a fair indication. To be sure you would need to test for continuity of all conductors (end to end and loop of phase and cpc/earth)
A radial circuit would have only one phase conductor to the MCB/Fuse, again this is not always the case and verification would be needed.

If I extend the circuit as you recommend, do I just run a cable from the existing socket to the new socket, then another cable back to the second cable in the first socket?

Extending the socket is a little more complexed than that, as you need to have a complete, uniformed ring, ideally without hidden joint boxes that are inaccessible, unless maintenance free ones are used.
The best way to extend an RFC would be by the addition of more than one socket.

Some helpful links:
RFC and Radials
//www.diynot.com/wiki/electrics:installation_techniques:route
//www.diynot.com/wiki/electrics:installation_techniques:walls
MF junction boxes

 

[dhutch]

And obviously, the standard warning that if you are having to ask these questions, although there is no harm in working out what you can or cannot do, that you should ultimatly get a qualified electrican to do the work.

There are various routes in finding someone, but when I moved to a new area I used the NIC EIC site.
http://niceic.com/Page/SearchContractors


Daniel

 

[ban-all-sheds]

I won't be installing it, but I'm trying to figure out what I want and where!) the rewiring of my kitchen, since knocking down a wall to combine our kitchen with the dining room.

Forget, completely, the rewiring.

Decide where you want your kitchen appliances, cupboards, walls etc, tell your electrician, and let him do the necessary.

The builder ....

Does he not have an electrician?

Can I therefore use this for the u/floor heating? Do I need to use thinner cable, or simply change the mcb in the fuse box? Or both?

Leave things like that to the electrician.

Could I even power the hob, oven and u/floor heating from this one cable?

Please stop trying to do electrical design work.

 

[ban-all-sheds]

I am also having underfloor heating.

Why?

What are you expecting it to do?

Have you checked if the floor has the necessary insulation? If not have you considered what it will be like having a step up into the kitchen?