Extending induction hob cable

[Sheyac]

Hi

I've notified building control of a full rewire at my house and am now doing kitchen wiring.

I have an induction hob rated at 7.2kW that due to the kitchen design is quite far from the isolator (2.3 meters). I'm thinking of joining the hob cable to 4mm t+e clipped direct using a wago 222 connector in a wago junction box as a maintenance free method (it'll be behind drawer units). I will then connect to the 45A isolator and then to a 32A type B MCB (with RCD). Is this acceptable?

Thanks in advance

 

[EFLImpudence]

Not quite sure which cable you intend to join.

Is it the one from isolator to hob?

 

[Sheyac]

Hi, thanks for replying.

I intend to join the hob flex to the 4mm t+e. I then run the 4mm t+e into the isolator. From the isolator again 4mm t+e into CU onto a dedicated 32A MCB.

The hob installation manual says a minimum 2x 16A breaker arrangement is to be used, guessing they wrote it that way as it can be connected to 2 phases or a single phase.

Thanks

 

[EFLImpudence]

I intend to join the hob flex to the 4mm t+e. I then run the 4mm t+e into the isolator. From the isolator again 4mm t+e into CU onto a dedicated 32A MCB.

Ok. You could do that, or
Replace the hob cable to use one piece, or
Use a cooker connector plate near the hob, which is the 'normal' way.

The hob installation manual says a minimum 2x 16A breaker arrangement is to be used, guessing they wrote it that way as it can be connected to 2 phases or a single phase.

Yes, that's for Europe.
You have one 32A supply - there should be an instruction for that as well.

 

[AndyPRK]

yeah I would put a cooker connection plate near the hob.

And ideally a switch near by in accordance with the regulations.

 

[winston1]

yeah I would put a cooker connection plate near the hob.

And ideally a switch near by in accordance with the regulations.

What regulations? There is no requirement for an isolation switch nearby.

 

[flameport]

yeah I would put a cooker connection plate near the hob.

Entirely normal.
How and where would the previously mentioned Wago connectors be used?

 

[Sheyac]

To maintain the streamlined design of the kitchen we have allocated an area for switches (grid switch and hob isolator) in the short section of an L-shaped worktop whereas the hob is on the long section, about 2.5 meters away from where we want to put the isolator.

I have a backbox (currently unused) behind drawer units - could that be used?

If I were to use the wago connector in a wago enclosure then I'd mount that underneath the hob/in the service void. But obviously that wouldn't be easily accessible without removing the hob and thought maybe the wago way being maintenance free would satisfy the regulations regarding accessibility of connections.

 

[EFLImpudence]

To maintain the streamlined design of the kitchen we have allocated an area for switches (grid switch and hob isolator)

Do you realise that none of these is required? They are just personal choices.

I have a backbox (currently unused) behind drawer units - could that be used?

Yes but as you are redoing the kitchen, why not do it 'properly' and use the proper connector below the hob.
There isn't much point having a maintenance free connector when you might have to remove the hob for some reason.

If I were to use the wago connector in a wago enclosure then I'd mount that underneath the hob/in the service void. But obviously that wouldn't be easily accessible without removing the hob and thought maybe the wago way being maintenance free would satisfy the regulations regarding accessibility of connections.

Yes but having to access it to fit the hob means it cannot be inaccessible.
How are you going to fit the hob if the area below it is inaccessible?

 

[Sheyac]

Thanks for the response. I think I may have caused confusion with what I'm describing.

The layout of the kitchen on the long side of the L is an inbuilt washing machine next to the wall, then a big drawer unit (above which sits the hob), then another drawer unit and finally a corner unit that wraps round the corner of the L shape. As there are only drawers and the washing machine in the vicinity of the hob then there isn't really an accessible place nearby that's not above the worktop. Above the corner unit on the the short side of the L is where we want to site the switches to keep them accessible but also out of the way.


But if I'm understanding your post there is no requirement for accessible emergency isolation for any kitchen appliance?

 

[EFLImpudence]

But if I'm understanding your post there is no requirement for accessible emergency isolation for any kitchen appliance?

That is correct.

 

[Sheyac]

But I suppose the question still stands. How do I connect the hob to the consumer unit which is too far from the hob to use the flex (short of replacing the cable entirely and possibly voiding the warranty)? Is there a way of connecting to 4mm t+e? Either using the backbox behind drawers or a wagobox? Ideally I want to avoid creating a blanked plate or isolator above worktop level.

 

[ban-all-sheds]

I've notified building control of a full rewire at my house

What did you say, or by default allow them to assume, would be your route to compliance with Part P?

... Is this acceptable?

But if I'm understanding your post there is no requirement for accessible emergency isolation for any kitchen appliance?

I can't square you asking questions like this with you being competent to design an electrical installation.

What's going to happen about this?:

I being the person responsible for the design, construction, inspection & testing of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the design, construction, inspection & testing hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2015 except for the departures, if any, detailed as follows:

 

[ban-all-sheds]

But I suppose the question still stands. How do I connect the hob to the consumer unit?

You don't, directly.

You connect the hob to a cooker outlet plate (on the cooker circuit) which is installed on the wall below the hob.

 

[Sheyac]

Building control will test and sign off the installation, not me. I have told them I am not a trained electrician. I have also not done anything unusual on the lighting or ring circuits.

My questions about accessibility are because the definitions are a bit vague - is it considered accessible if I need to remove a kitchen drawer to access the connection for maintenance and inspection? What about if I have to remove the hob to access the connection?

The questions about isolation are because I see a lot of kitchens littered with FCUs above a worktop or grid switches (especially in new builds) - surely if an accessible means of isolation isn't required then the cheapest and easiest way of satisfying the regs would be to not install them! So why do they bother? And why have a big/ugly/expensive 45A neon lit isolator for the hob if its not needed? Makes me wonder if I'm missing a requirement or not reading regs correctly.