Induction hob for preexisting 4mm T+E

[Jackster]

I have been told by a local spark that one can not run an induction hob on a 4mm T+E.

From my understanding, most induction hobs are 7-8kW and "require" 6-10mm T+E but our housebuilder only put 4mm because they are cheap.
Or maybe I am cheap for not coughing up £500 for a £150 induction hob "upgrade" when we bought...

Anyway, there is a 4mm T+E installed and I don't want my local spark coming and running new cable in my new build house. CBA with the mess.

I am aware of the 13amp ones but after using a full-power one at my old house, doubt a 13amp one will suffice my expectations.

So are there any mid-powered induction hobs models out there that can run on 4mm?

Note that a 2kW oven will have to be moved onto the kitchen circuit if I get this done.
We have a microwave, dishwasher, washing machine, kettle and Foodi Ninja (2kW pressure-cooker/grill machine).
All these devices won't be on at the same time so this should be okay on the kitchen circuit? B32 breaker in the CU.

Also, if 4mm should not be used on 32amp equipment. Why did my house builder put the 4mm T+E on a B32 breaker?

 

[Baddegg]

Also, if 4mm should not be used on 32amp equipment. Why did my house builder put the 4mm T+E on a B32 breaker?

4 mm is fine, (installation conditions permitting) On a 32a breaker, depending on installation method 4 mm will carry a max 46a (not with a 32a ocpd obviously)....although to be honest I think I’d have paid for the larger cable at build stage to future proof and save all this grief but good luck with it ?

 

[davesparks]

I have been told by a local spark that one can not run an induction hob on a 4mm T+E.

Note that a 2kW oven will have to be moved onto the kitchen circuit if I get this done.

Also, if 4mm should not be used on 32amp equipment. Why did my house builder put the 4mm T+E on a B32 breaker?

Did the local spark support this statement with any reference to the wiring regulations?

A 2kW oven shouldn't be put on the socket circuit, it's not strictly prohibited but strongly advised against.

Depending on the installation conditions and cable calculations 4mm could be used for a 32A circuit. Was this actually installed by the builder, or was it an electrician working for the builder?
Do you have an electrical installation certificate for the installation?

 

[buzzlightyear]

From my understanding, most induction hobs are 7-8kW and "require" 6-10mm T+E but our housebuilder only put 4mm because they are cheap.
Or maybe I am cheap for not coughing up £500 for a £150 induction hob "upgrade" when we bought...

Most manufacturers put in a cable to the rating of the hob plus tells inthe installation book what rating of the cable to use.

 

[littlespark]

A lot of these hobs come with a flex cable attached to connect to the cooker outlet, and they’re lucky if it’s 4mm.

yes, I know, the type of flex has a different ccc to t&e

the circuit should have been 6mm to begin with. Majority of people have seperate hob and oven now, and the two could be doubled up, rather than oven on rfc with every other high powered kitchen appliance.

 

[Lucien Nunes]

A 25A MCB can get you out of trouble with 4.0mm as a couple of methods give an Iz between 25 and 32A.

 

[HappyHippyDad]

Did the local spark support this statement with any reference to the wiring regulations?

A 2kW oven shouldn't be put on the socket circuit, it's not strictly prohibited but strongly advised against.

Depending on the installation conditions and cable calculations 4mm could be used for a 32A circuit. Was this actually installed by the builder, or was it an electrician working for the builder?
Do you have an electrical installation certificate for the installation?

I know you're a stickler for precision Dave so I'll correct you a little, of course I fully expect you to point out my unseen error .
Cookers/ovens/hobs with a rated power exceeding 2kW on their own dedicated radial circuit (Appendix 15, note (iii)). So a 2kW cooker would be deemed OK on a socket circuit, a 2.01kW cooker would however require a dedicated circuit.

 

[telectrix]

I know you're a stickler for precision Dave so I'll correct you a little, of course I fully expect you to point out my unseen error .
Cookers/ovens/hobs with a rated power exceeding 2kW on their own dedicated radial circuit (Appendix 15, note (iii)). So a 2kW cooker would be deemed OK on a socket circuit, a 2.01kW cooker would however require a dedicated circuit.

oops, davesparks and hippyhappy---- handbags at dawn.

 

[Jackster]

Interesting info. Thanks for the replies, everyone.

So it is pretty much safe to say the 4mm T+E can handle the induction hob, and the over can go on the kitchen circuit.
Though ideally there should be a 6mm T+E with both on that.

Best bet would be a 6kW induction hob to be on the safe side?

 

[davesparks]

I know you're a stickler for precision Dave so I'll correct you a little, of course I fully expect you to point out my unseen error .
Cookers/ovens/hobs with a rated power exceeding 2kW on their own dedicated radial circuit (Appendix 15, note (iii)). So a 2kW cooker would be deemed OK on a socket circuit, a 2.01kW cooker would however require a dedicated circuit.

That is a good point, it is indeed on the borderline.

I guess it's going to come down to whether the power rating is just the element or if it includes the electronic clock and the lamp in the oven
[automerge]1594386885[/automerge]

So it is pretty much safe to say the 4mm T+E can handle the induction hob, and the over can go on the kitchen circuit.

Maybe, maybe not, we haven't seen the actual installation to be able to make that decision.

 

[Jackster]

Doh, I just double-checked the oven and it is 2,075 watts not 1900 watts.
Think I was looking at another oven a few weeks ago trying to get a better one.

Maybe, maybe not, we haven't seen the actual installation to be able to make that decision.

Ah...

It goes from the understands cupboard to the kitchen in the ceiling cavity.
Don't believe there is any insulation up there. And it should be clipped?

 

[FatAlan]

Do your heat and smoke alarms work ok?

 

[telectrix]

Doh, I just double-checked the oven and it is 2,075 watts not 1900 watts.
Think I was looking at another oven a few weeks ago trying to get a better one.



Ah...

It goes from the understands cupboard to the kitchen in the ceiling cavity.
Don't believe there is any insulation up there. And it should be clipped?

bear in mind yhat thatis the total ratingof the oven. youprobably won't be able to use oven and grill elements together, and even so, it's under 9Amps. can'tseea problem on the socket ring unles you have a washing macine and tumble dryer on at same time as oven. anyway, we all plug a 3kW kettle in and nobody bats an eyelid.

 

[7029 dave]

Its been done for decades, everybody knows a dedicated 32amp cooker circuit should be run in 6mm minimum.

 

[Pretty Mouth]

Its been done for decades, everybody knows a dedicated 32amp cooker circuit should be run in 6mm minimum.

@7029 dave , I would install 32A on 6mm too, just because it's always done that way. But I often wonder why? I could see 6mm being necessary for voltage drop concerns, or if using rewireable fuses. In the absence of these, and assuming method C, why wouldn't a 4mm conductor suffice?

 

[Ian1981]

6 mm for a cooker circuit is a throw back to the older 3036 fuses, where 6mm on a 30 amp fuse was the norm as it dealt with the issue of the fusing factor of the 3036 fuses being 2 rather than 1.45 , I2 < 1.45 Iz.
So a 6mm for a cooker circuit has just been recycled down the line without any thought on actual design.
Considering that a 15kw load is fine for a 32 amp mcb with diversity taken into account, 4mm is quite adequate for a cooker circuit, obviously if the calculations allow it, the same as any other selected conductor.

 

[davesparks]

Its been done for decades, everybody knows a dedicated 32amp cooker circuit should be run in 6mm minimum.

But everybody knows that a 32A socket radial should be 4mm, so what's the difference? Same size OCPD, same calculation, different cable size?

'everybody knows' isn't always correct, it can just mean that a lot of people are wrong.

6mm is traditionally used for cooker supplies yes, but that is out of tradition, not calculations. It harks back to the imperial cable sizes where the size used for a 32A radial was nearer to 6mm and so people just started using 6mm.

 

[7029 dave]

@7029 dave , I would install 32A on 6mm too, just because it's always done that way. But I often wonder why? I could see 6mm being necessary for voltage drop concerns, or if using rewireable fuses. In the absence of these, and assuming method C, why wouldn't a 4mm conductor suffice?

The OP stated it is a new build so method C is out the window we have been told that, which will reduce the CCC thats why 4mm wont suffice.

 

[Ian1981]

The OP stated it is a new build so method C is out the window we have been told that, which will reduce the CCC thats why 4mm wont suffice.

Why is method C out the window?
Our company do new builds, method C is common to a lot of the circuits installed

 

[7029 dave]

But everybody knows that a 32A socket radial should be 4mm, so what's the difference? Same size OCPD, same calculation, different cable size?

'everybody knows' isn't always correct, it can just mean that a lot of people are wrong.

6mm is traditionally used for cooker supplies yes, but that is out of tradition, not calculations. It harks back to the imperial cable sizes where the size used for a 32A radial was nearer to 6mm and so people just started using 6mm.

I would use the term common sense other than tradition, out of interest given the info we have, what size cable would you select.?
[automerge]1594462859[/automerge]

Why is method C out the window?
Our company do new builds, method C is common to a lot of the circuits installed

My understanding is that is a surface install.