Induction hob plus oven wiring - rating?

[les24preludes]

Hi guys, I need to have an induction hob and oven connected up. Units are:
Hob: AEG HK654400XB Induction hob - HK654400XB | AEG - https://www.aeg.co.uk/kitchen/cooking/hobs/induction-hob/hk654400xb2/
Oven: Miele H2561BP Miele Ovens | H 2561 BP Oven - https://www.miele.co.uk/domestic/ovens-1451.htm?mat=10116060&name=H_2561_BP

There is an existing cooker circuit with isolator. Each wire, pos and neg, inside the isolator has an outer diameter including PVC cover of 5mm. So I need to know:
1. What the existing wiring is in cable size/capacity
2. If this is enough allowing for diversity
3. Or do I need a new feed from the fuse box for the induction hob, which seems the more greedy of the two.
Can someone fill me in on where to go here? I do know some basic DIY electronics so would understand ratings.

 

[telectrix]

generally, the existing circuit would be 6mm ( cross section, not diameter)and that is fine for up to 15kW (total rating) of cooking appliances. what size MCB is protecting the cable? best advice is to get a local spark to check and test the circuit and then advise on whether it will cope .

 

[les24preludes]

The cooker fuse for the existing circuit is 45A. Not sure if the cable is 6mm or 10mm. Can anyone give me a definitive answer based on the fact that the OD of each single wire is 5mm including PVC cover? What's that?

 

[westward10]

Is the bare earth solid or stranded.

 

[Christopher Bernard]

You could always measure the diameter if you're really that unsure.

10mm² ((√(10/π)) x 2) = 3.56mm diameter.
6mm² ((√(6/π))x 2) = 2.76mm diameter.
4mm² ((√(4/π))x 2) = 2.25mm diameter.

 

[Taylortwocities]

More tricky than that. The cable will be composed of 7 strands, so measure a strand, apply the formula and multiply by 7 to get the measured csa of the cable.
Hope you have a micrometer!
Not so easy, this electrickery stuff, is it?

 

[westward10]

Only this forum can blow things totally out of proportion.

 

[les24preludes]

Sounds like 6mm. Looking up Farnell specs, 6mm total OD is 4.85mm, rated 48A. Fuse is 45A That sounds close. 10mm is OD 6.3mm which is more than the 5mm I measured.

Using Ohm's law, 230v at 48A is 11kW which is what's required in total. Looks borderline but not impossible.

Earth is insulated yellow/green. Wiring was put in in the 1980s.

 

[telectrix]

is it a 45A fuse or a MCB? or are you going by the isolator rating?

 

[les24preludes]

It's a simple 1980s fuse box. 220x170mm. Space for 6 fuses and master on/off on RH. Cooker circuit has a 45A fuse.
Isolator has an on/off switch and a red light. 150mm by 90mm

 

[westward10]

Does this cable have a single solid earth or a stranded earth.

 

[les24preludes]

Looks like it's stranded like the pos and neg, with green/yellow PVC sheath.

 

[Taylortwocities]

I do know some basic DIY electronics so would understand ratings.

like the pos and neg

Les, please get someone on site who knows how electricity works.

 

[les24preludes]

Les, please get someone on site who knows how electricity works.

What's your point here - are you referring to me or what?

 

[telectrix]

he's basically saying that you are out of your depth and should seek the services of an electrician.

 

[telectrix]

Les, please get someone on site who knows how electricity works. Kills

corrected that for you.no charge.

 

[les24preludes]

OK - 2 points here. I've been designing and building tube amplifiers for 10 years and I can assure you they are complex designs and they all work. I said I was familiar with DIY electronics, tubes in my case. Not electrical house and appliance wiring and the associated regs. That's something else. So please no more sarky comments. I will be using an electrician to do the work - I'm not doing this myself. I'm just planning it at this stage because I want to know if the existing circuit is adequate for the load. Any questions?

 

[westward10]

So is the earth solid or stranded.

 

[les24preludes]

So is the earth solid or stranded.

Are you reading this thread? It's stranded with a yellow/green PVC cover.

 

[westward10]

If it is a flat T&E then having a stranded earth there is every chance it is 10.0, can you show a pic.

 

[Bobster]

So please no more sarky comments. I will be using an electrician to do the work - I'm not doing this myself. I'm just planning it at this stage because I want to know if the existing circuit is adequate for the load. Any questions?

Well, we've never heard that before haha.

 

[telectrix]

Are you reading this thread? It's stranded with a yellow/green PVC cover.

6.0mm is generally a solid cpc (earth core). 10.0mm is stranded. however, it could be imperial cable, 7/036 or 7/044. sorry to add to the confusion.

 

[Taylortwocities]

What's your point here - are you referring to me or what?

Yes, I was referring to you. There is no positive and negative in AC circuitry. Well there is, if you look at an AC sine wave.

But my point is that if you are thinking black is -ve and red is +ve, then you need to concentrate on other aspects of DIY than Electricity.

Sorry to be hard, but trying to stop you getting out of your depth.

 

[les24preludes]

Ah, right. Thanks for that. I have people coming over so no time now. I'm just going on what I can see with a torch inside the insulator, which I can only get about an inch off the wall. It doesn't look like a flat T&E. There are 3 wires, all stranded PVC sheathed. OD of each is 5mm including the sheath. Looking at Farnell specs, 6mm is 4.85mm OD which looks right and 10mm is 6.3mm OD which looks too thick. But as you say, it's not T&E inside the insulator.

 

[westward10]

Can you show a pic.

 

[westward10]

6.0mm is generally a solid cpc (earth core). 10.0mm is stranded. however, it could be imperial cable, 7/036 or 7/044. sorry to add to the confusion.

Assuming metric being an 80s property.

 

[telectrix]

Ah, right. Thanks for that. I have people coming over so no time now. I'm just going on what I can see with a torch inside the insulator, which I can only get about an inch off the wall. It doesn't look like a flat T&E. There are 3 wires, all stranded PVC sheathed. OD of each is 5mm including the sheath. Looking at Farnell specs, 6mm is 4.85mm OD which looks right and 10mm is 6.3mm OD which looks too thick. But as you say, it's not T&E inside the insulator.

look on the bright side. at least you'll not be tempted into buying a gas oven and sticking your yed in it.

 

[les24preludes]

OK - I see the point about AC. Just not thinking since I build DC circuits in electronics and when I see red and black wires my head goes "pos and neg". So going back to the point of the thread
1. How do I know if this is 6mm or 10mm wiring? 10mm is fine.
2. If it's 6mm wiring, and given the travel is 7 metres from the fuse box, is this circuit Ok for 11kW? Looking into this, I came across the following calculations:
100% of first 10amps and 30% of remaining load, add 5 amps if a 13a outlet in control unit. So 11kw= 47.83amps at 230v
30% of 37.83 = 11.349
11.349+10= 21.349a
So a 6mm cable should satisfy the regs. Does this sound correct?

 

[telectrix]

OK - I see the point about AC. Just not thinking since I build DC circuits in electronics and when I see red and black wires my head goes "pos and neg". So going back to the point of the thread
1. How do I know if this is 6mm or 10mm wiring? 10mm is fine.
2. If it's 6mm wiring, and given the travel is 7 metres from the fuse box, is this circuit Ok for 11kW? Looking into this, I came across the following calculations:
100% of first 10amps and 30% of remaining load, add 5 amps if a 13a outlet in control unit. So 11kw= 47.83amps at 230v
30% of 37.83 = 11.349
11.349+10= 21.349a
So a 6mm cable should satisfy the regs. Does this sound correct?

correct. as long as the cable is not covered in insulation, 6.omm .is good for a cooker/oven circuit up to 15kW (allowing for the diversity that you mentioned). you seem to be over complicating the issue.

 

[les24preludes]

Diversity covers a multitude of sins. I was thinking of a perfect storm like a Christmas dinner with a roasting turkey and four rings on the go on an induction hob. But as you say, that's probably overthinking things. Or alternatively setting the Miele oven on self-clean at the same time as cooking up a few kilos of boiled vegetables for a vegan lunch.... That's probably seriously overthinking it.....

 

[DPG]

at the same time as cooking up a few kilos of boiled vegetables for a vegan lunch.... That's probably seriously overthinking it.....

Vegan lunch - I'd stick the cooker on a 6A MCB then to make sure it tripped out!

 

[les24preludes]

Vegan lunch - I'd stick the cooker on a 6A MCB then to make sure it tripped out!

Good thing I'm not a vegan..... I'd also imagine that the percentage of vegan electricians may be on the small side.