James94 Posted January 23, 2022 Share Posted January 23, 2022 (edited) Are we worrying for no reason? In the middle of having first fix electrics and got to the kitchen and he wants to do a separate radial for ovens and fridge freezer in 2.5mm. He says he’s done the calculations and this is all it requires. the pics show cables hanging In position and similar to what we want ovens like. Edited January 23, 2022 by James94 add pics Link to comment Share on other sites More sharing options...
ProDave Posted January 23, 2022 Share Posted January 23, 2022 Ovens don't actually use that much power, typically 2kW for a single oven. It is hobs that draw much more power. If you feel more comfortable and future proof use 4mm or 6mm for an oven feed, nothing wrong with being too big. Link to comment Share on other sites More sharing options...
James94 Posted January 23, 2022 Author Share Posted January 23, 2022 @ProDave thanks for the quick reply, been looking at the Bosch 8 series steam oven, oven, microwave/ovens, some are total kw 3.3 , 3.6kw Are these type low consumption? I might speak to him Wednesday and ask him to use 4mm, does a radial make any difference to having a ring? having an induction job in island on its own radial in 4mm. regards. James Link to comment Share on other sites More sharing options...
Dan F Posted January 23, 2022 Share Posted January 23, 2022 A lot of the new ones do have pyrolytic cleaning and/or fast heating modes though, and therefore are up to 3.7kW (16A). If you don't know what oven you are getting yet, you should ensure he allows for 16A. I would personally expect, and insist on, 4mm for anything that may be up to 16A. That is what our electrician has used. 1 Link to comment Share on other sites More sharing options...
Dan F Posted January 23, 2022 Share Posted January 23, 2022 (edited) 14 minutes ago, James94 said: does a radial make any difference to having a ring? Ovens/hobs are suppsoed to be radial, with dedicated isolator and i think breaker too. 14 minutes ago, James94 said: induction job in island on its own radial in 4mm What is the rating of the hob. Ours needed 6mm form what I remember. Edit: Our Bora hob is 7.6kW. It has 6mm wiring, dedicated isolator in the kitchen and its own 32A breaker (or RCBO, can't remember) in the consumer unit. Radial for fridge, dishwasher, freezer etc. is a good idea as it allows you to have a grid of isolators for all appliances in one place. Edited January 23, 2022 by Dan F Link to comment Share on other sites More sharing options...
James94 Posted January 23, 2022 Author Share Posted January 23, 2022 @Dan F I’m hoping to be able to afford the ovens I’m looking at and hope will all have pyrolytic cleaning so I will ask him to change it to 4mm,just piece of mind and more future proof. radials, they are all going to be on one radial, do they not have to be on there own individual radial or all on one ok? hob, my dream hob is the bora x pure. Which will be in island, now thinking might need bigger cable too,I’ll get spec. Regards. James Link to comment Share on other sites More sharing options...
James94 Posted January 23, 2022 Author Share Posted January 23, 2022 Link to comment Share on other sites More sharing options...
Dan F Posted January 23, 2022 Share Posted January 23, 2022 (edited) Yes, definitely get those upgraded. Easy now, not later. Quote do they not have to be on there own individual radial Yes, between per-appliance isolator and appliance. In terms of back to your consumer unit, they don't all need their own dedicated circuits nesecaily i don't think (although they often do) but there are limits/guidelines and you cant put everything on one either i don't think. Hopefully an electrician on the forum can coment on this.. Edited January 23, 2022 by Dan F Link to comment Share on other sites More sharing options...
James94 Posted January 24, 2022 Author Share Posted January 24, 2022 Multiphase supply voltage 380 – 415 V 2N/3N Single-phase supply voltage 220 – 240 V Frequency 50/60 Hz Maximum power consumption 7,6 kW (4,4 kW / 3,6 kW) Three-phase power supply/fuse protection 3 x 16 A (standard connection) Two-phase power supply/fuse protection 2 x 16 A Single-phase power supply/fuse protection 1 x 32 A (1 x 20 A / 1 x 16 Don’t understand these figures, our property will be single phase. How many wires will the hob require, at the minute the electrician has laid a 6mm cable.There will be plug sockets in the island too. regards. James Link to comment Share on other sites More sharing options...
Mr Punter Posted January 24, 2022 Share Posted January 24, 2022 9 minutes ago, James94 said: Don’t understand these figures, our property will be single phase. How many wires will the hob require, at the minute the electrician has laid a 6mm cable.There will be plug sockets in the island too. regards. James The 6mm T&E will be fine for this. The Sparky should make the choices on cable sizing, runs, isolation etc. It is his job to know. 1 Link to comment Share on other sites More sharing options...
Luke Salter Posted January 24, 2022 Share Posted January 24, 2022 for the X Pure... its one 32amp supply. 7.6kw. the info you have listed is for the Bora Classic . Link to comment Share on other sites More sharing options...
James94 Posted January 24, 2022 Author Share Posted January 24, 2022 Oh didn’t realise just got details from here, says x pure at top of page. https://www.bora.com/gb/gb/cooktop-extractor-systems/bora-x-pure/product/puxa/ so we will keep the 6mm he’s running to hob and ask him to change the cookers cable to 4mm. he has done all calculations and seem very knowledgeable, I don’t like questioning him but I just thought the cookers wire was to small.I’ll just say I want to future proof. Regards. James Link to comment Share on other sites More sharing options...
PeterW Posted January 24, 2022 Share Posted January 24, 2022 Why upgrade to 4mm for a single oven ..? A 2.5mm cable will handle 23-25A, and a number of the Bosch units come with a fixed lead that is only 1.5mm anyway. Up to 4.5kW then you are in the boundaries of a 20A RCBO, 20A isolator and 2.5mm cable 1 1 Link to comment Share on other sites More sharing options...
James94 Posted January 24, 2022 Author Share Posted January 24, 2022 We are hoping to have something similar to this or 4 ovens, this is why we a little concerned with 2.5mm radial. Regards. James Link to comment Share on other sites More sharing options...
PeterW Posted January 24, 2022 Share Posted January 24, 2022 But a radial is just rhat - it should feed a single oven via a single RCBO and an isolator. If you have 4 ovens, it is 4 radials. What it sounds like is that you want multiple ovens on the same circuit, and you need to be able to isolate each one (20A DP switch per oven) via an accessible switch. That would need a 4mm cable to the first point and then spur off for each oven with a switch, and for 4 ovens you need to consider diversity but you could even need a 6mm feed. 2 Link to comment Share on other sites More sharing options...
Dan F Posted January 24, 2022 Share Posted January 24, 2022 (edited) Sorry @James94 I was just sharing what our electrician used previously, @PeterW is right. I guess our electrician used 4mm because he was considering the 2.5mm 17A minumum rating (?). If you look it up though, this only applies to 60C rated cables, so they were being fairly conservative. With a 32A hob though, it seems 4mm is cutting it fine (would required 90C cable). If you give your electrician the Bora X Pure specs, he should know what to do. It's likely just a case of him assuming a hob with a lower rating. Edited January 24, 2022 by Dan F Link to comment Share on other sites More sharing options...
James94 Posted January 26, 2022 Author Share Posted January 26, 2022 Finally got him to change the wire, took some persuading but now have 4mm to cookers and 6mm to hob. I feel more at ease now that's sorted, thanks for everyone's help and advice. Regards James Link to comment Share on other sites More sharing options...
Nickfromwales Posted January 26, 2022 Share Posted January 26, 2022 Don’t be surprised if the electrician asks you if want to take over the installation on his behalf!! The guy will be qualified, working to the spec of the fixed equipment and appliances that YOU have give to him, and will have installed what is correct. 2.5mm2 radial to each oven with its own 20a DP switch is absolutely spot on for anything up to the 16a requirements. Converting now to 4mm is just a waste of time and money. On 24/01/2022 at 18:44, Dan F said: I guess our electrician used 4mm because he was considering the 2.5mm 17A minumum rating (?). Now we’re getting silly ?. That’s for adverse installations. Never once have I heard any domestic sparky quote or install to that allowance. Cables for domestic ask for an ambient of 20oC to be used, then possibly grouping factors etc may then affect the outcome, but a good sparky will mitigate that simply with segregation. Stick with the 2.5mm and get yourself off to the pub 1 Link to comment Share on other sites More sharing options...
Kelvin Posted September 4, 2023 Share Posted September 4, 2023 Holy thread resurrection and thank heavens for buildhub. We are boarding out and joiner commented on the size of the oven cables. We have two separate radial cables for the ovens. I said what’s wrong with them and he said they don’t look big enough. The ovens are 3.3 kW at 16A so installed 2.5mm cable. He reckoned they should be 4mm of even 6mm. I said no that’s completely unnecessary for ovens as they use very little power but you’d use it for induction hobs like we are. He still insisted that every kitchen he fits has much bigger cables for the ovens. Of course he’s got me doubting myself but the sparky knows his job and I shared the oven specs with at fit out time. Just spent 30 mins googling and found this thread. Sanity restored. I’ll tell him to stick to bashing in nails. 😂 1 Link to comment Share on other sites More sharing options...
TonyT Posted September 4, 2023 Share Posted September 4, 2023 How far away if the consumer unit? Link to comment Share on other sites More sharing options...
Kelvin Posted September 4, 2023 Share Posted September 4, 2023 3m Link to comment Share on other sites More sharing options...
TonyT Posted September 4, 2023 Share Posted September 4, 2023 2.5mm2 is more than adequate, tell joiner you are worried about the thickness of the partition timbers and start him worrying! 1 Link to comment Share on other sites More sharing options...
Temp Posted September 4, 2023 Share Posted September 4, 2023 Many builders run fatter cables on the assumption that someone might want to replace their oven with an oven and hob in the future. Link to comment Share on other sites More sharing options...
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