Sorry another... gas hob & single oven Q!

goo · 28 Aug 2006

Hey guys would be grateful of any advice here...

EXISTING - We have a gas cooker wired to an outlet box below the worktop, fed from Cooker connection unit with integral switch above the worktop. The CCU is supplied from the fuse box by 6mm cable (radial)with 30amp fuse.

PROPOSED - The old gas cooker is being replaced by a new electric single oven (2250w) which has a plug and a new gas hob (electric ignition) which also has a plug. According to instructions both can simply be plugged into a socket.

Ideally I would like the hob and oven to be plugged into sockets below the worktop, (or wired to flex outlets) and fed by FCU's above the worktop. However I still would like to use the existing radial which supplies the old cooker. What would be the simplest way of doing this?

?? Could the new oven be wired to the existing cooker outlet box as before (below worktop)and change the CCU for a 20amp DP switch (above worktop)?Would then a spur from the switch to a FCU (to supply the hob) be ok?

Hope there is enough info above to create a clear pic - any comments would be most appreciated!

The Jeep · 28 Aug 2006

How about this:
Replace the cooker outlet below the worktop with a double unswitched socket.
Put 13A plugs on each appliance to protect them and their cables.
Replace the cooker control unit with a 20A DP switch + neon.
Replace the 30A fuse with a 15A one (or 16A MCB if you upgrade the CCU).
The DP switch now controls the complete cooker electrics. The 6mm² cable is now way over-rated, but that's OK. The new fuse will protect the circuit from overload.
Oh yes, have the circuit tested, particularly with regard to earthing.

The Jeep · 29 Aug 2006

Hey Goo, how's it working out for ya?
I should add that you should fit the fuse rating in the plugtops that the manufacturers recommend for their appliances (and cable if supplied).

goo · 30 Aug 2006

Terrific! That makes things nice and straight forward - thanks for your good advice Jeep!

Both hob and oven have fused plugs already fitted and will get the circuit tested.

One last Q though... we also have a hood (again with plug fitted), is it possible to connect this to the kitchen radial so that all associated appliances work from the same circuit? i.e. a spur from the 20A DP switch to a FCU?

The Jeep · 30 Aug 2006

Hi Goo, glad to be of assistance - I don't see any particular advantage in having the associated hob hood/extractor on the same circuit as the cooker; it would be quite happy on the kitchen ring, with an appropriate (3A likely) fuse in its plug.
But, yes, your idea would work and then you could just run 2.5mm² from the FCU (fitted with a 3A fuse) to a single unswitched socket by the hood (surface clipped or chased & capped) and put a 13A fuse in the hood plug so the one in the FCU would blow in preference, making it easier to change.
Your cable linking the 20A DP switch and the FCU should be the same rating as that going to the CCU.
I guess you should do what's most convenient, as long as the appropriate protection is there.

JohnD · 30 Aug 2006

A flex outlet by the hood will look much neater than a plug and socket. It is unfused so no duplication with the fuse in the FCU.

The Jeep · 30 Aug 2006

Sounds good, John D

goo · 30 Aug 2006

Hey guys...

Think I will go with supplying the hood from the 20A DP switch as it's going to be much easier to do this rather than from elsewhere on the kitchen circuit.

The flex outlet is a great idea - will look better than a socket and plug.

Think that thats me all sorted out! Thanks for all your advice - very much appreciated.

Cheers

RF Lighting · 30 Aug 2006

If you use a flex outlet you need to use a FCU, rather than a 20A DP switch, otherwise the cooker hood will not be protected by the correct size fuse.

A 20A DP switch is fine if you use a plug and socket arrangement to connect the hood.

JohnD · 30 Aug 2006

Very good point, RF, I must have missed that

(All these cooker hood questions are starting to look alike to me)

You can get an FCU with cord grips and facility for a flex outlet which could be used up by the fan if you like, with a 3A or 5A fuse in it.

goo · 30 Aug 2006

My thinking on this was...

From the 20A DP switch take a spur for a FCU (which will be located 150mm above worktop height near to the switch) which will then control the flex outlet installed near the hood.

I realise that you can get the FCU's with the flex outlet but thought that running the flex from the hood down to this level would look untidy... so thought the flex outlet idea would be perfect.

What do you guys think?

The Jeep · 31 Aug 2006

Erm, I actually meant, as Goo suggested, a switched FCU in line with the DP switch at worktop level, then going up to the socket outlet (now flex outlet, which looks neater, I agree). That way the fan can be easily switched off/on from next to the main cooker isolator.
Someone must be doing a cheap run of electric cookers, eh...?

pinns · 3 Sep 2006

Long time Lurker, first time Poster, go easy on me!

Have been reading Goo's post with interest , it matches my situation except I have MCB fuses in CU.
I got a bit confused along the way, so can I summarise what I have understood from your replies, feel free to jump in and correct me:

1) There is an existing dedicated cooker circuit of 6mm cable from 30a fuse in consumer unit.

2) Goo changes cooker connection point under worktop for a double unswitched socket, (with appropriately rated fuses in each plug for oven and hob ignitor).

3) Replaces existing neon cooker switch above worktop to a 20a DP switch with neon.

4) Changes 30a fuse in consumer unit for 15a (or in my case, 16a MCB) to protect his new appliances.

5) From DP switch runs 6mm cable a short distance to site of new switched FCU (3a fuse) above worktop.

6) Runs 2.5mm cable (chased into wall?) up to flex outlet situated near to hood, then connects hood flex into outlet.

7) Gets Electrician to test.

Did I miss anything?

---------------------

Sorry to be so annoying/pedantic, but I wanted to make sure I had grasped all your points!

Also, I am still uncertain about point 6 - does the cable from FCU to Flex Outlet have to be as large as 2.5mm cable or can it be 1.0mm, and is it ok to bury this in the wall? (behind tiles)

Many thanks for your assistance!

pinns

The Jeep · 3 Sep 2006

pinns said:
Long time Lurker, first time Poster, go easy on me!

.............>>>>>>>>

Also, I am still uncertain about point 6 - does the cable from FCU to Flex Outlet have to be as large as 2.5mm cable or can it be 1.0mm, and is it ok to bury this in the wall? (behind tiles)

Many thanks for your assistance!

pinns

The Jeep · 3 Sep 2006

Sorry, I messed up: just been having some beers, but still feel able to advise on this:

Firstly, welcome pimms, glad you've come out from lurking behind your VDU....

You're spot on with what you say, but I am rethinking things here and would suggest that a regular 45A cooker control unit, particularly a nice 1-gang one, would be better than the 20A DP. It will probably come with a neon and appropriate labelling, like 'cooker'. This keeps everything nice 'n' chunky in case anyone wants to upgrade the oven some time.

But, yes, 2.5 mm² for the run to the fan outlet from the FCU, as this future-proofs things and it's not a great deal of expense. By all means bury it in a chase, cover it with capping, then filler and or plaster then tiles.

Hope this helps!

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Sorry another... gas hob & single oven Q!

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