Single ovens on 6mm cable

[surreysparks]

I have a customer who has bought 2 single ovens both drawing approx 3.4kw. Instructions state not to be connected to plug top/sw spur, fair enough.
Existing cooker wired in 6mm back to board on 32a mcb. When met with this situation before have wired new circuit back to board with 16 or 20a mcb and downrated existing mcb to same to cover both ovens.
Its a no no to run new cable back to board, tiles, laminate, panelling etc.
Only option I can think of is 2 module enclosure with 2 16a mcb`s. This can be mounted in housing top box. Any thoughts? Would you still have 2 20a D.P switches for isolation or are the 2 mcb`s sufficient for this purpose.?

 

[riveralt]

Are you saying you are a qualified electrician because if you are you should certainly know the answer the question you are raising.
Do you understand the purpose of an MCB?
Do you know how to calculate diversity?
At the very least you be able to find a solution in the on site guide.

 

[ban-all-sheds]

Are you saying you are a qualified electrician

Looking at his previous posts it seems that he definitely claims to be.

 

[ebee]

Three reasons that you might be using a certain MCB & cable combination in any circuit.

1/ Short circuit

2/ Earth fault

3/ Overload

If the load is limited by virtue of its characteristics ie it is a fixed load like a cooker or shower then you might not need 3/.

If you decide that an earth fault is covered by an RCD then you might not need 2/

(although most designers would only consider this in a TT installation and still rely on 2/ and merely consider the RCD to be a back up protection in this respect in a TN installtion)

It might be best to consult an electrician if you going down the building control notification route

 

[PrenticeBoyofDerry]

So what about when you are considering the rating of DP switches? As the OP surprisingly has a problem with this!

 

[plugwash]

Getting back on topic what do the manufacturers instructions say? Do they specify a specifc rating (or range of ratings) of protective device must be used? if so what do they say? If they say "max MCB 20A" or whatever then you need to respect that.

If you are planning to hide the box containing the MCB then you should provide easilly accessible switching like you would with any cooker to allow it to be turned off quickly in the event of problems.