Advice on ensuring wiring is ok for new oven & hob...ple

[flameport]

It is highly unlikely that the new oven will require a 16A supply. More likely is that the total power of the grill and oven element combined is 3.6kW, and therefore when in use, the actual power is substantially less since both elements can't be used simultaneously.

The installation therefore consists of unplugging the old oven, and plugging the new one in.

If for some reason the new oven does actually use 3.6kW to heat a single oven cavity, I suggest you don't get that one, as it will simply increase your electricity bill for no noticeable benefit.

 

[ajrobb]

I suggest you keep the original certificates showing the 40 A rating for the cooker circuit. I suspect they would be needed if someone later wants to replace the new B20 RCBO with 32 A or 40 A. Your sparks should be able to advise.

 

[holmslaw]

..

 

[Stevethetiler]

Hahaha

Well, my old 2.8kw oven says 16a in the book but came with a 13a fused plug on the end of it!

I would prefer to err on the side of caution as its a £1000 oven and I imagine the draw on it can be quite high due to a pyrolitic cleaning cycle.

Say, for some reason, I had the oven on a pyrolitic cycle, and ignited the hob to fry an egg or something, thats the ONLY thing I would want to be frying!

Just got off the phone with one electrician who said, "nah mate....you will be fine with your existing 40a RCBO...."

Now, im thinking that having my oven fused that high isnt such a hot idea. I think (unprofessionally ofcourse) that 20a would be close to the actual rating of the oven and hob combined. (18a all in all) and that tis size RCBO (20a) would be the safest route to take.

 

[echoes]

What's the model number of the oven?

Usually the instructions state a minimum current rating for the circuit protection & isolation switch. The oven isn't capable of overloading a 40A circuit (or a 20A circuit, come to that), so either breaker would protect the cable against fault current.

 

[Stevethetiler]

What's the model number of the oven?

Usually the instructions state a minimum current rating for the circuit protection & isolation switch. The oven isn't capable of overloading a 40A circuit (or a 20A circuit, come to that), so either breaker would protect the cable against fault current.

I havent got it YET so I would have checked the book for more details BUT the oven is a Hotpoint with model no. of OS897DPIX - its a single oven with a large space that can be used as a double oven with a divider - also has the pyrolitic feature so i want to be doubly sure wiring is up to snuff....

Hope that helps!

 

[holmslaw]

..

 

[JohnD]

The 40A circuit was obviously designed for an all-electric cooker, and may be useful in future. Your 13A plug and socket are very convenient for fusing down for a 13A oven. It's very tiresome that the manufacturer has put a single oven on the UK market which nearly, but not quite, suits a 13A supply.

If it was my own house, I would be very tempted to run it on a 13A plug. The worst that could happen is that the plugtop fuse might blow, probably when it was on a pyrolitic cycle. More likely, though it wouldn't. Ovens rarely run at max load for long. This would also save the trouble and expense of altering the existing cooker circuit and RCBO (which is notifiable work).

Even changing the cooker circuit to a submain would IMO be preferable, then you could have a small kitchen CU with (say) a 6A gas hob, 40A electric coooker; and 16A or 20A oven supply, and then you could fit pretty well any appliance according to your whim.

 

[echoes]

The MI's state to connect this 3600W appliance to a standard plug(!). I doubt this will happen. No mention of requirements to fuse down.
Also instructions given to fit the cable to the oven itself.

So your 40 MCB would offer reasonable protection to the cable. It would also be reasonable to replace the 40A breaker with a 20A one.

Clicky

 

[JohnD]

The UK plug incorporates a fuse, so this will fuse down the 40A supply to 13A for you.

I can't find that oven on the Hotpoint UK website ovens page http://www.hotpoint.co.uk/hotpoint/2/products.do#/p/Ovens/pline/15/startMode/catalogo/

The MIs refer to a standard plug; but also say the power is 3400W to 3600W so this does not make sense for the UK*, I suspect it has been designed for a continental market and translated thoughtlessly into English. I see the website is actually on Indesit.

In Germany I have seen electric cookers plugged in using a typical 2-pin plus earth round plug, which looks rather undersized by UK standards

*It might be worth taking this up with the manufacturers and saying your current oven is supplied via a UK 13A plug and socket, so you want another one that connects the same way (i.e. was designed with the UK market in mind). UK single ovens usually are.

 

[Stevethetiler]

The UK plug incorporates a fuse, so this will fuse down the 40A supply to 13A for you.

I can't find that oven on the Hotpoint UK website ovens page http://www.hotpoint.co.uk/hotpoint/2/products.do#/p/Ovens/pline/15/startMode/catalogo/

The MIs refer to a standard plug; but also say the power is 3400W to 3600W so this does not make sense for the UK*, I suspect it has been designed for a continental market and translated thoughtlessly into English. I see the website is actually on Indesit.

In Germany I have seen electric cookers plugged in using a typical 2-pin plus earth round plug, which looks rather undersized by UK standards

*It might be worth taking this up with the manufacturers and saying your current oven is supplied via a UK 13A plug and socket, so you want another one that connects the same way (i.e. was designed with the UK market in mind). UK single ovens usually are.

This is the oven http://www.johnlewis.com/230718887/...396-8348-a30d-0000459c3f98&s_kwcid=paidsearch but its coming direct from Hotpoint themselves as a replacement.
The John Lewis site says 32a circuit...another different instruction lol.

I had thought about just putting a 13a plug on it but prefer to do things properly. I dont want to be changing fuses all the time no matter how infrequent it may be.

For the small cost involved (the RCBO is about £25, the dual CC plate is £6 and say, maybe £30 for the labour to do it), wouldnt it be better to just bite the bullet?

It *may* run fine with the 40a circuit fused down to 13a at plugtop, but I wouldnt be installing within the remit, would I? (how can any oven wiring be "easily accessible" when hardwired behind it as most ovens that require hardwiring are connected in this fashion - a plate behind the oven housing that the oven sits in! - unless you classify 2 screws and pulling the oven out as being "easily accessible!)

Obviously, if my existing 40a RCBO is going to do the job and not be a safety issue, I can avoid the cost of a spark and the new 20a RCBO and simply wire the Dual connection plate myself. Hardwire oven to one load outlet and the socket in the cupboard from the other load outlet (6mm). The gas hob would then be fused down via the 3a plug and my oven will be hardwired into the plate by Hotpoint.

The only downside to that, as others mentioned earlier, I would have a normal 13a socket on a 40a circuit.......so, I presume thats why its recommened to change the RCBO....

Note: I was not able to get a like for like replacement, the one on offer is an upgrade F.O.C so I really would like to take advantage of it. I dont have another choice really regarding ovens as I dont want to downgrade it (which was the only other alternative via warranty)

 

[echoes]

You'll never install that oven satisfactorily in the UK by following the instructions to the letter.
A fly in the ointment might be if your HOB needs fusing down to 3A. The MI's may say it does, but the OSG says that you may consider the combination of oven and hob as a single appliance on a suitably rated circuit (like your 40A one) ...

...so a dual outlet plate for your existing oven + gas hob on a 40A RCBO or 20A RCBO meets the requirements of the regs per se.

If in doubt then a single cooker outlet for the oven next to a single socket or unswitched FCU for the hob does the job, and would be about as compliant with MI's for both oven and hob as you could get.

 

[JohnD]

echoes, are you sure a 40A circuit and a 15A cooker are compliant? I'd have to think about where to look. The cooker cable would also have to be 6mm in order to be protected.

If so, then fitting a socket and a cooker outlet would be the most economical and least disruptive work. It would also mean he could change over to a huge electric range cooker in future if he wanted.

 

[echoes]

Well I'm not 100% certain and will be corrected gratefully, but consider the case of having two 3 kW ovens, or a 3 kW oven + 7 kW hob connected to a 40A circuit.
In this case the cables between the oven(s) and the outlets would not be designed to carry 40A, but they would never be expected to carry more than the load of an oven. The cables would however be protected against a short circuit fault.
There is nothing to stop the OP from running a 6mm² cable to his oven though, for the avoidance of doubt.

It's also analogous to the unfused-spur-on-ring scenario: the 2.5mm² spur cable is protected by a 32A breaker, which does not provide overload protection to the cable. But since that spur cable is not capable of being overloaded by anything you can reasonably be expected to connect to it (ref methods permitting), it's deemed OK (as we know).

 

[ajrobb]

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