Cooker Isolation Socket Fault

[Longclough]

I post the following post about wiring of a double oven and gas hob:

//www.diynot.com/forums/viewtopic.php?t=222222&postdays=0&postorder=asc&start=0[url][/url]

I had an Electrician carry this out for me. In the end he used the existing double socket and added a spur using 6mm2 to a cooker connection unit and then 6mm2 to the double oven.

When the electrician had finshed the wiring when he switched the breaker back on, there was no power to either the oven or hob. He checked all the wiring had a installed and found no fault. The electrician then asked if the cooker isolation switch had been disconnected, which it hadn't. On removing the socket cover to have a look at the wiring the oven powered up and gas hob worked. He checked the wiring and it all seemed ok.

Just after he had left I powered up the oven and heard a crackling sound from the cooker isolation switch. I got the electrician back and he believes that the isolation switch is faulty and is going to replace it. Is this likely to just be the cooker isolation or could this be down to something else?

 

[electronicsuk]

Unless the wiring is loose at the back of the switch, it could well be faulty.

I haven't read your original post, but don't like the sound of the part about "using the existing double socket". How much power does the oven require? Is this a dedicated circuit? I wouldn't be so concerned if it weren't for the fact that he probably didn't test his work, otherwise he would likely have found the fault before it came to switching on the oven.

 

[Longclough]

Yes it is an existing cicuit. Hob is gas so plugs in. Hence the socket, although only a single is really required. Oven is 4.9 Kw

Connected as follows:

CU (32 Amp MBC) --> 6mm2 --> Cooker isolation switch --> 6mm2 --> Double socket (gas Hob plugged in) --> spur to cooker connection unit --> 6mm2 to Oven

The previous wiring was up to the double socket. The electrician checked the double socket, cooker connection unit and wiring at double oven prior to switching the breaker.

 

[ColJack]

switching the cooker switch off may have killed it..
it was probably on it's last legs anyway..

try flipping it a few times to see if you can rub the oxidisation off the contacts..

 

[Longclough]

Electrician said he would just replace it. He wasn't confident in the current socket.

Coljack he adopted a simlar solution to your solution in my original post, although not quite as neat, but if it does the job I am happy and its hidden away.

 

[electronicsuk]

CU (32 Amp MBC) --> 6mm2 --> Cooker isolation switch --> 6mm2 --> Double socket (gas Hob plugged in) --> spur to cooker connection unit --> 6mm2 to Oven

Sounds fine then.

 

[kerai]

Sorry to reply to an old post.

I have a similar problem I have run a new 6mm cable from the consumer box, I have also purchased a 32amp fuse for the consumer box.

However I am not sure what I need to do next, ie do I need a 13amp spur switch or a 45amp cooker switch or can I connect the 6mm directly to the 3.6KW oven. (Please note nothing else is or will be connected to this circuit)

Thanks

MK

 

[holmslaw]

..

 

[kerai]

Thank you for advise Holmslaw, I have already booked an electrician to come over the weekend. I was only laying the new 6mm cable under the floorboards to cut on labour cost and purchasing the connection/connectors required.

The reason I also ask is because I have spoken to a qualified electrician who said a single oven can be connected to a 13amp socket, however I read my oven installation manual and it says this appliance should NOT be connected to a 13amp plug or spur. This has confused me.

Are you a qualified electrician and what is your professional advise.

Thank you

 

[Chri5]

You need to have the cable isolated between the appliance and CU, either a cooker switch, a cooker switch and socket (since there's ono o'load issues on the circuit you have suggested) or a simple 20 amp dual pole switch (which might suit asteticallly).

The logic is fire and service, both would require the oven to be isolated.

It is not acceptable to use the CU as a form of isolation for the circuit.

NB for 3600w / 3.6 kw oven = / 230v = 15.6 amps

On that basis a 20 amp fuse and a modest 2.5TE cable could have been used. A 30 amp / 4mm would have covered a cooker switch with a socket (13 amps socket + 15.6 amps =29 amp ish)

The 6mm is a good idea should you ever need a electric hob

 

[kerai]

Hi Chris

Thank you so much for your response.

Please correct me if I am wrong.

The electrician would simply connect the 6mm cable to the CU to a 32amp RCD Fuse.
Then, in the kitchen the 6mm cable is connected to a isolatation switch (cooker switch of 20amps NOT the 45amp) and from this the appliance is connected.

Thank you

MK

 

[Chri5]

Correct, just have to make sure the 20 amp switch has decent terminals. A 20 amp switch wouldn't normally have to cope with a 6mm cable.

If you want to future proof (as mentioned at some future date the gas hob may become electric and at that time the 20 amp switch wouldn't be suitable) use a cooker switch.

Hence way most run a 40 amp circuit in 6mm on to a 40 /45 amp cooker switch. It allows for all combinations of cooking appliance type.

 

[kerai]

Perfect response. Nice to know people understand, care and are willing to share their knowledge.