Do I need an electrician to replace a hob?

[Rubber_Duck]

One of the elements on our ceramic hob has failed. Can I replace it with a similar ceramic hob myself or am I required to get an electrician to fit it? I've undertaken many minor electrical wiring jobs around the house over the years, so this is within my capabilities.

The existing hob has a rating of 6.0kW and it runs off the same 6mm cable as the oven which is rated at 5.4kW (32A MCB at the consumer unit). The circuit was installed by an electrician when our kitchen extension was built. I'd like to replace the hob with a Hisense one rated at 6.4kW. Is the extra 400W significant or can it be considered like for like? The old hob is 20 years old and no longer made.

 

[pete01]

The 400w wont make a difference and yes you can do it, just be careful when connecting into the hob as they are usually, really tight and a bit rubbish.

 

[morqthana]

Unless you (or another family member) has a pacemaker, get an induction one.

 

[Rubber_Duck]

Unless you (or another family member) has a pacemaker, get an induction one

We looked at one from IKEA that was a Which best buy. It has a 7.35kW rating. My understanding is that it would require its own 6mm cable.. I know there's such a thing as diversity but I was thinking about times like Christmas dinner when you've got every ring and both ovens on. I was under the impression that a 6mm cable wouldn't be able to handle the current draw.

We are planning to re-do the kitchen in a year or two, so was just looking for a quick and easy solution to tide us over.

 

[pete01]

Nope that would be fine aswell even at Christmas.

 

[JohnD]

32A MCB at the consumer unit

32A x 230V is 7360W

More than enough.

 

[Rodders53]

Get an Induction Hob rather than Ceramic (as long as you have magnetic base cooking pans). Much better control of cooking stuff.
NB It may be possible to repair the hob with a replacement of the failed element from a parts supplier.

Oven and Hob on same circuit? Diversity allows it: It is calculated as 10 A plus 30% of the full-load current that exceeds 10 A (plus 5 A if a socket is on the control unit).
32A MCB:
oven 5.4 kW + hob 7.4 kW = 12.8 kW (@230 V) = 51.3 Amps.
10 + (0.3 x 41.3 =12.4) + 5 = 27.4 or 22.4 if no 13A socket on the 'cooker' (oven and hob) control switch.

Induction hobs can be crippled set to a lower max current in their electronics if there is a trip issue found in practice. (Very very unlikely... we've been using cooker diversity in the UK for an exceedingly long time).

 

[Rubber_Duck]

32A x 230V is 7360W

More than enough.

Ok. So, if I understand both you and Pete 01 ...
Even though the total load of dual oven & induction hob would be 12.75kW, it's still ok to run both on a single 6mm cable which can only support 7.36kW because of diversity (all appliances not drawing at maximum load simultaneously). Is this correct?

 

[Rubber_Duck]

Get an Induction Hob rather than Ceramic (as long as you have magnetic base cooking pans). Much better control of cooking stuff.
NB It may be possible to repair the hob with a replacement of the failed element from a parts supplier.

Oven and Hob on same circuit? Diversity allows it: It is calculated as 10 A plus 30% of the full-load current that exceeds 10 A (plus 5 A if a socket is on the control unit).
32A MCB:
oven 5.4 kW + hob 7.4 kW = 12.8 kW (@230 V) = 51.3 Amps.
10 + (0.3 x 41.3 =12.4) + 5 = 27.4 or 22.4 if no 13A socket on the 'cooker' (oven and hob) control switch.

Induction hobs can be crippled set to a lower max current in their electronics if there is a trip issue found in practice. (Very very unlikely... we've been using cooker diversity in the UK for an exceedingly long time).

Sorry, only saw this after I posted my reply to JohnD. Thanks for the calculation which explains it. My preference would be to go with induction, however, I've been married long enough to leave it to the wife to make the final call.

 

[Rubber_Duck]

Thanks everyone for helping me out on this. It's been very interesting learning how things work.

 

[pete01]

Ok. So, if I understand both you and Pete 01 ...
Even though the total load of dual oven & induction hob would be 12.75kW, it's still ok to run both on a single 6mm cable which can only support 7.36kW because of diversity (all appliances not drawing at maximum load simultaneously). Is this correct?

Yes thats right you can have upto 15kw, even 20kw would be ok.

 

[ericmark]

Unless you (or another family member) has a pacemaker, get an induction one.

The new pacemakers it seems are now compliant, and can be used with the induction hob.

I know there's such a thing as diversity

The induction hob puts a larger % of energy into the food, and the food needs the same amount of energy as it has always needed, so an induction hobs average power use must be less than a resistive hob. And the MCB/RCBO if correctly sized will just trip should too much current be used, so no danger. But highly unlikely it will trip.

My stand-alone cooker with an induction hob with all switched on together can use around 70 amps, but it has never tripped a 32 amp overload.

We went for stand alone, because the oven was better, it has things like closed door grilling, mothers built in oven, also had closed door grilling, but it used a timer to keep swapping power between the elements, where the stand alone ran both together, so closed door grilling worked with the stand alone, but was an unused gimmick with the built-in oven.

However although the stand alone is better at cooking, to have an eye level oven does have some advantages, don't need the extra room for wife's bum when she bends down to use the oven. Why anyone would put a built in oven under the hob, I have never worked out, the whole idea of a built in oven is not needing to bend down to use it.

 

[JohnD]

You have an extra room for it?

 

[mikehammer69]

The new pacemakers it seems are now compliant, and can be used with the induction hob.

The induction hob puts a larger % of energy into the food, and the food needs the same amount of energy as it has always needed, so an induction hobs average power use must be less than a resistive hob. And the MCB/RCBO if correctly sized will just trip should too much current be used, so no danger. But highly unlikely it will trip.

My stand-alone cooker with an induction hob with all switched on together can use around 70 amps, but it has never tripped a 32 amp overload.

We went for stand alone, because the oven was better, it has things like closed door grilling, mothers built in oven, also had closed door grilling, but it used a timer to keep swapping power between the elements, where the stand alone ran both together, so closed door grilling worked with the stand alone, but was an unused gimmick with the built-in oven.

However although the stand alone is better at cooking, to have an eye level oven does have some advantages, don't need the extra room for wife's bum when she bends down to use the oven. Why anyone would put a built in oven under the hob, I have never worked out, the whole idea of a built in oven is not needing to bend down to use it.

Now that you mention it it’s a truly awful layout the oven under the hob

If i recall some kitchen fitters used to put the oven at worktop level which was great and then the microwave on top in of it which was too high altogether

I’d always have microwaves stand-alone anyhow they always seemed to give so much trouble

Mostly about managing space . Off the top of my head I reckon kitchen fitters are obsessed with counter space

 

[morqthana]

We went for stand alone, because the oven was better, it has things like closed door grilling,

You can't see what's going on with closed door grilling. I actually bought a standalone wall mounted electric grill because I like to see what's going on....