Is my existing feed suitable for this:

[EFLImpudence]

Ah, I missed your previous post. Could they have been added to the cooker breaker?

No, the ovens could have been just added to the cooker circuit in the kitchen.


I think I misunderstood your terminology.

He meant make the new cables a new 32A ring circuit which would be alright.
I thought you meant he was just going to join two 20A circuits together.

 

[Mottie]

No, the ovens could have been just added to the cooker circuit in the kitchen.


I think I misunderstood your terminology.

He meant make the new cables a new 32A ring circuit which would be alright.
I thought you meant he was just going to join two 20A circuits together.

The cooker feed which was for the old cooker is going to be utilised for the new induction hob. (Previously had a gas hob above the oven). The new cookers are going to be sited in a different position, nowhere near the hob and the LVT floor would have had to come up to extend that to the new oven locations.

Yeah, excuse my terminology. A new ring circuit from the spare 32a breaker will be just for the two ovens.

 

[EFLImpudence]

The cooker feed which was for the old cooker is going to be utilised for the new induction hob. (Previously had a gas hob above the oven). The new cookers are going to be sited in a different position, nowhere near the hob and the LVT floor would have had to come up to extend that to the new oven locations.

Fair enough.

Yeah, excuse my terminology. A new ring circuit from the spare 32a breaker will be just for the two ovens.

 

[briwire]

You wouldn't be able to tap into your "ring main" for those two appliances as you are limited to 13 amps, either via a plug or spur. So assuming the 20kW diversity stated above, you would be able to use the same supply as the one feeding the hob. The difficult part I would expect would be to fit two 6mm cables into your isolator so choose carefully. You could also end up with three 6mm cables in one box, which might be a bit tight. Try to choose one with plenty of room.

 

[EFLImpudence]

You wouldn't be able to tap into your "ring main" for those two appliances as you are limited to 13 amps, either via a plug or spur. So assuming the 20kW diversity stated above, you would be able to use the same supply as the one feeding the hob. The difficult part I would expect would be to fit two 6mm cables into your isolator so choose carefully. You could also end up with three 6mm cables in one box, which might be a bit tight. Try to choose one with plenty of room.

I think you are getting more confused than I was.

The ovens are each more than 13A anyway.

Cooker outlet plates could be used for each oven.

 

[Mottie]

To clear up any confusion, a new 2.5mm ring circuit is going to be created using the spare 32A breaker in the consumer unit. All that is going to be on that circuit will be two 20A double pole switched outlets. One for each oven as they are both just over 3Kw. The end!

 

[JohnW2]

To clear up any confusion, a new 2.5mm ring circuit is going to be created using the spare 32A breaker in the consumer unit. All that is going to be on that circuit will be two 20A double pole switched outlets. One for each oven as they are both just over 3Kw. The end!

Although they are "both just over 3kW" [i.e. just over 13A], after application of diversity they would both represent loads of less than 13A.

 

[Mottie]

Although they are "both just over 3kW" [i.e. just over 13A], after application of diversity they would both represent loads of less than 13A.

Everyone keeps mentioning 'Diversity'. My mate mentioned it too. What has a street dance troupe got to do with my kitchen electrics….…..

 

[JohnW2]

Everyone keeps mentioning 'Diversity'. My mate mentioned it too. What has a street dance troupe got to do with my kitchen electrics….…..

Not a lot, but it has a meaning in relation to electrical items, particularly cooking appliances

If (as with cooking appliances) they are thermostatically controlled, it is very unusual for all the bits (oven elements, hob rings etc.) to all be drawing current simultaneously and continuously for long periods of time, since each of them 'cycles on and off', under the control of thermostats

As a result, the average amount of power consumer (i.e. average current) over an appreciable period of time (say 30 mins, probably less), which is what determines cable heating etc, will be appreciably less than the total if 'everything were drawing current simultaneously and continuously throughout that period.

The usual calculation for domestic cooking appliances says that the 'after diversity' current (effectively the average current over an appreciable period of time) is "the first 10 A plus 30% of the rest of the theoretical maximum current (with 'everything drawing current simultaneously).

Hence,for example, if the 'rating' of a cooking appliance (which is that 'maximum with everything on simultaneously') were, say, 30 A, then the 'after diversity' ('average') current, used for design purposes would be 10 A plus 30% of the other 20 A - i.e. just 16A

Hope that helps.

 

[Mottie]

If (as with cooking appliances) they are thermostatically controlled, it is very unusual for all the bits (oven elements, hob rings etc.) to all be drawing current simultaneously and continuously for long periods of time, since each of them 'cycles on and off', under the control of thermostats

My mate said something similar but he said if you have them on the same circuit as your dishwasher, washing machine, kettle etc then I might throw the breaker if I have them all on, hence putting them on their own circuit.

 

[JohnW2]

My mate said something similar but he said if you have them on the same circuit as your dishwasher, washing machine, kettle etc then I might throw the breaker if I have them all on, hence putting them on their own circuit.

That's certainly a theoretical possibility, so it makes sense to have the cooking appliances on their own circuit (which is the 'usual' situation'). It may have seemed that I was, but I wasn't really uintending to imply/suggest otherwise.

However, given that the new circuit is going to just be feeding the two cooking appliances (and nothing else), it would probably be simpler (and probably a bit cheaper) for it to be a 4 mm² radial circuit, rather than a 2.5 mm² ring circuit.

 

[Mottie]

However, given that the new circuit is going to just be feeding the two cooking appliances (and nothing else), it would probably be simpler (and probably a bit cheaper) for it to be a 4 mm² radial circuit, rather than a 2.5 mm² ring circuit.

Probably would be if I didn’t have best part of a roll of 2.5mm t&e left over from…….2001. I'm still using red and black for L & N!

 

[JohnW2]

Probably would be if I didn’t have best part of a roll of 2.5mm t&e left over from…….2001. I'm still using red and black for L & N!

Fair enough. I still have a fair bit of black/red cable!

You could just use two runs of 2.5 mm² in parallel, to create a "5 mm² radial" (rather than a 2.5 mmª ring) if you so wished.

 

[ebee]

yep,
if you treat 2 x 2.5 as 5.0mm conductors and a 3.0 earthwire then you will not be far wrong, although a little bit of interpolation on the current carrying capacity, volt drop and expected Zs might be required because they are non standard sizes to look up in tables. The nearer the lengths match the better your "guess" would be.

 

[EFLImpudence]

There are certain regulations for "conductors in parallel".

You can't just count two separate wires that you have connected as such.