Quick oven wiring question

[JohnW2]

Ok well seeing as you both have said that 1.5 would do, I could just use the existing 1.5 which I believe is butyl already, and then buy some of that online. Then I could return the screwfix lot and get back the huge amount they charged me!

Fair enough.

actually its currently H05RR-F

As you probably know, the 'RR' indicates that it is rubber insulated and rubber sheathed and, as you said, that's probably butyl.

Kind Regards, John

 

[ekmdgrf]

Ok so it looks like i'll be safe with 2.5 then. I can't get 4mm anywhere this evening anyway and need to fit it today really.

It would be good to hear some other opinions, but I would personally be happy with 2.5mm² flex.

First thing to check would be the manufacturer's instructions. My oven is iirc, 2.2KW. It ran quite happily on a 13A plug while I was refurbing the kitchen. Yet the MI state the device must be supplied by 2.5mm cable.

Personally I'd wire it in 2.5mm cable and down the MCB to a B16. This argument has been had before and I think it was largely agreed that it was hard to conceive a situation where you'd end up with a fault that drew > 16A but < 32A, so there was nothing wrong with leaving the MCB as it is.

 

[JohnW2]

First thing to check would be the manufacturer's instructions. My oven is iirc, 2.2KW. It ran quite happily on a 13A plug while I was refurbing the kitchen. Yet the MI state the device must be supplied by 2.5mm cable.

Well, no matter how you look at it, that's a silly MI! .. roll on the BYB next year

Personally I'd wire it in 2.5mm cable and down the MCB to a B16. This argument has been had before and I think it was largely agreed that it was hard to conceive a situation where you'd end up with a fault that drew > 16A but < 32A, so there was nothing wrong with leaving the MCB as it is.

Indeed. Not only 'nothing wrong with it' but, if one is happy that it is 'unlikley' that the oven could create an 'overload' (as opposed to a negligible impedance 'fault') - which is surely true of an oven - then it is also regs-compliant. As you imply, for the ultra-cautious/nervous, a B16 and 2.5mm² flex is obviously 'foolproof' - but a B32 and even 1.5mm² flex would also, in reality, be 'OK'.

Kind Regards, John

 

[monkey73]

ok so there are obviously many conflicting opinions.

I have ordered the 2.5mm Butyl cable from TLC so as I understand, I have these options:

1)

32A MCB (As it is now) ---> 6mm2 T+E ---> 45A Cooker supply socket with extra socket for hob ---> Direct connection from back of this socket to oven in 2.5mm2 Butyl Flex.

2)

16A MCB (Change from 32A) ---> 6mm2 T+E ---> 45A Cooker supply socket with extra socket for hob ---> Direct connection from back of this socket to oven in 2.5mm2 Butyl Flex.

Option 2 means opening up the CU and changing the MCB which i've not done before. If i DO do this and leave everything else the same including the 2.5mm butyl cable, then are all the other components in the chain correct? (i.e the 6mm cable and the 45A socket?)

Option 1 for all intents and purposes is correct from what people have said, but it is not necessarily to "done thing", is that right? But it's perfectly safe and it's a very unlikely scenario that it would be a problem. If i've understood all that correctly then it's much easier for me to go with option 1. If someone can confirm this (again!), that would be great.

Also if anyone is wondering, I knew I oversized the circuit for my current needs, but the oven I'm putting in now will only be in place for a short while before I gut the kitchen and build an extension and have a much bigger double oven or 2.

 

[EFLImpudence]

Option 1 for all intents and purposes is correct from what people have said,

Yes.

but it is not necessarily to "done thing", is that right?

No.

But it's perfectly safe and it's a very unlikely scenario that it would be a problem.

It's less than unlikely.

If i've understood all that correctly then it's much easier for me to go with option 1. If someone can confirm this (again!), that would be great.

Yes, there is no doubt.

Also if anyone is wondering, I knew I oversized the circuit for my current needs, but the oven I'm putting in now will only be in place for a short while before I gut the kitchen and build an extension and have a much bigger double oven or 2.

When you do that you can connect it to the same outlet.
A much bigger double oven consists of the same parts; just more of them.

 

[JohnW2]

ok so there are obviously many conflicting opinions.

I don't think it's as bad as it may seem. I think every approach which has been suggested would be compliant with regulations - it's primarily that some people feel inclined to be even more cautious than those regulations!

I have ordered the 2.5mm Butyl cable from TLC so as I understand, I have these options:
1) 32A MCB (As it is now) ---> 6mm2 T+E ---> 45A Cooker supply socket with extra socket for hob ---> Direct connection from back of this socket to oven in 2.5mm2 Butyl Flex.
2) 16A MCB (Change from 32A) ---> 6mm2 T+E ---> 45A Cooker supply socket with extra socket for hob ---> Direct connection from back of this socket to oven in 2.5mm2 Butyl Flex.

Yep, the only difference being whether you stick with the 32A MCB or change to a 16A one.

Option 2 means opening up the CU and changing the MCB which i've not done before. If i DO do this and leave everything else the same including the 2.5mm butyl cable, then are all the other components in the chain correct? (i.e the 6mm cable and the 45A socket?)

Yep, but unless you have the knowledge and skill to be competent and confident/comfortable to be opening up the CU and changing the MCB, you probably shouldn't attempt to do that yourself.

Option 1 for all intents and purposes is correct from what people have said, but it is not necessarily to "done thing", is that right?

I wouldn't personally say so. The great majority of cooker circuits are 32A (sometimes even higher), yet I rather doubt that people often use flex larger than 2.5mm² to connect 16A (or lower powered) cookers/ovens to them.

But it's perfectly safe and it's a very unlikely scenario that it would be a problem. If i've understood all that correctly then it's much easier for me to go with option 1. If someone can confirm this (again!), that would be great.

As you have observed, opinions (about 'extreme cautiousness') vary, but I would personally be totally happy with it.

Also if anyone is wondering, I knew I oversized the circuit for my current needs, but the oven I'm putting in now will only be in place for a short while before I gut the kitchen and build an extension and have a much bigger double oven or 2.

As above, I would say that a 32A/6mm² cooker circuit was by far the most common one comes across, so I wouldn't say that it is really 'oversized'.

Hope that helps.

Kind Regards, John

 

[monkey73]

Good, thanks to both again, I think we can put this to bed with option 1 and be done as dusted!

Thanks

 

[JohnW2]

Good, thanks to both again, I think we can put this to bed with option 1 and be done as dusted! Thanks

You're welcome. That's certainly what I would do. Even though I would be comfortable changing the MCB, I wouldn't bother.

Kind Regards, John