Two circuits off cooker switch?

[xr4x4]

Just to clear things up.

Kitchen hasn't been touched since the 80s, single bloke, gonna live out his days there. Kitchen probably never gonna be touched again.

AEG say 16amp dedicated supply for both microwave and oven, which is bonkers for a microwave.

Cooker aegbp7304001m
Microwave aegmcd2664em

So 32amp cooker supply gonna be split into two 2.5te, spider fashion each to there own outlet plate.

 

[JohnW2]

So 32amp cooker supply gonna be split into two 2.5te, spider fashion each to there own outlet plate.

If both oven and microwave are going to be hard-wired (which is what you seem to imply - i.e. no plugs/sockets), then those runs of 2.5mm² cable protected only by a 32A MCB is really not acceptable, unless you can argue that the appliances 'cannot create an overload' (conceivable argument for oven, unlikley for microwave). If both are rated 3 kW or less, then you could put in two 13A FCUs.

Kind Regards, John

 

[xr4x4]

Nope just checked, both need 16amp supply's.

The 2.5 will be shorter than 2 meters.

 

[JohnW2]

Nope just checked, both need 16amp supply's.

So the manufacture says (perhaps because the appliances were designed for mainland Europe). However, what do they specify as the maximum load/power of the appliances?

The 2.5 will be shorter than 2 meters.

If, as I suggested would probably be the case for the microwave (and possibly for the oven), the appliance is consdiered 'capable of producing an overload), then 2.5mm² protected only by a 32A MCB would not be acceptable, no matter how short the run. You could avoid that problem by using 4mm² cable, assuming it wasn't buried in insulation or something like that!.

Kind Regards, John

 

[xr4x4]

Hmm.. When I first created this post I didn't know the output of both the appliances. I guessed the oven would be 13/16a and the microwave would have a 13a plug.

Oven is 3500w so 16a, even though AEG say a min of 20amp fuse.
Microwave 1400w, grill 1000w, 15 amp fuse minimum. Microwave and grill can be used at tHe same time so 2400w, 10 amps.

I could continue the 6mm to a double ccu behind both the oven and microwave (same place) and wire them to that.

Only trouble with that is the oven and microwave will be fused at 32amps, which would be against mf requirements.

Bugger.

 

[sparkwright]

To be in line with the manufacturer's instructions, you could

Run one 6 mm2 cable from the wall switch to a new 2 way consumer unit fitted in a nearby kitchen cupboard.

At the 2 way board, fit one 20 amp MCB and one 16 amp MCB (as desccribed in the MI, right?).

Then from the new board run one 2.5 mm2 to one appliance,

and from the new board run another 2.5 mm2 to the other appliance.

 

[JohnW2]

Oven is 3500w so 16a, even though AEG say a min of 20amp fuse.
Microwave 1400w, grill 1000w, 15 amp fuse minimum. Microwave and grill can be used at tHe same time so 2400w, 10 amps.
I could continue the 6mm to a double ccu behind both the oven and microwave (same place) and wire them to that.

If you're quoting those instructions verbatim, ie that they specify only the minimum fuse sizes, then to have them both protected by a 32A MCB would obviously be compliant with those instructions. If that were the case, you could do as you say with a double outlet plate. Strictly speaking, the (probably flexible) cables from the outlet to the appliances would both have to be at least 4mm² if they were protected only by a 32A MCB (give or take the arguments I previously mentioned regarding appliances 'not able to create an overload').

Were it not for those MIs, application of diversity would allow the oven (as well as microwave) to be fed through a 13A FCU or 13A plug. Life might be easier next year!

Kind Regards, John

 

[EFLImpudence]

Nobody is going to quote a minimum size fuse or at least shouldn't.

 

[JohnW2]

Nobody is going to quote a minimum size fuse or at least shouldn't.

If they were talking about protection, you would obviously be right. However, they might just be using 'minimum fuse size' as a way of indicating (what they believe to be) the minimum current-providing 'capacity' of the circuit. I've certainly seen 'minimum fuse/MCB sizes' stated in instructions.

Kind Regards, John

 

[EFLImpudence]

More instructions from the Marketing Department.

 

[xr4x4]

AEG quote a minimum fuse size of 15a for the microwave.

http://media.datatail.com/docs/manual/161617_en.pdf

Page 31

 

[JohnW2]

More instructions from the Marketing Department.

Maybe - but if they want to specify a minimum circuit supply capacity, how else can they do it other than by talking about the fuse or MCB size? After all, in the absence of an OPD, a final circuit is theoretically able to supply as much current as the cutout fuse can tolerate and/or the maximum current which can flow before the cable melts (whichever happens first!)!

To merely state a maximum fuse/MCB size (for protection) could easily (and undoubtedly sometimes would!) presumably lead to some people trying to run appliances off circuits inadequate to supply them!

If they also have considerations of protection (presumably because their product does not have adequate internal protection), then maybe they should state both minimum and maximum fuse/MCB ratings?

Kind Regards, John

 

[EFLImpudence]

All they have to do, which is what I thought they did, is state that the appliance requires, for example -

a 16A supply (minimum for operation) and/or

a 16A fuse (maximum for safety because of appliance or flex supplied).

Maybe - but if they want to specify a minimum circuit supply capacity, how else can they do it other than by talking about the fuse or MCB size? After all, in the absence of an OPD, a final circuit is theoretically able to supply as much current as the cutout fuse can tolerate and/or the maximum current which can flow before the cable melts (whichever happens first!)!

They state how much current their appliance requires.
It is then up to someone who knows what they are doing to decide the circuit arrangements.
Hence, why the manufacturer states that "This appliance must only be connected by a competent person/qualified electrician".

To merely state a maximum fuse/MCB size (for protection) could easily (and undoubtedly sometimes would!) presumably lead to some people trying to run appliances off circuits inadequate to supply them!

I do feel your tolerance and understanding for idiots is getting rather excessive.
If the maximum supply is for safety then it is correct.
Hence, why the manufacturer states that "This appliance must only be connected by a competent person/qualified electrician".

If they also have considerations of protection (presumably because their product does not have adequate internal protection), then maybe they should state both minimum and maximum fuse/MCB ratings?

You do not need a minimum fuse/MCB rating.
An appliance requires a minimum supply for operation and may require a maximum opd for safety.
Hence, why the manufacturer states that "This appliance must only be connected by a competent person/qualified electrician".

 

[JohnW2]

All they have to do, which is what I thought they did, is state that the appliance requires, for example -
a 16A supply (minimum for operation) and/or
a 16A fuse (maximum for safety because of appliance or flex supplied).

Well, yes, but as I said, there isn't really any way (of which I know) of defining a (minimum) "16A supply" other than by saying that it has to have a fuse/MCB with a minimum of 16A rating. In other words, what you are saying above actually becomes:
"a supply with a minimum fuse of 16A and/or a supply with a maximum fuse of 16A."
... which is essentially what I said.

You do not need a minimum fuse/MCB rating. An appliance requires a minimum supply for operation and may require a maximum opd for safety. Hence, why the manufacturer states that "This appliance must only be connected by a competent person/qualified electrician".

As above, one effectively does require a minimum fuse/MCB rating, since that is the only way I know of expressing what the "minimum supply for operation" is. Do you know some way of specifying a minimum required supply other than by specifying a minimum fuse/MCB rating?

As I said before, there may also (but not necessarily) be a requirement for a maximum OPD for safety (in which case I see no alternative but to quote minimum and maximum OPD ratings - which could be the same). It's all very well citing the instruction that installation should be undertaken by a competent person/qualified electrician - but, at least until some same next year, (s)he is, strictly speaking, constrained by whatever the manufacturer may 'instruct'.

Kind Regards, John

 

[xr4x4]

I agree having a minimum is rather pointless, it's down to the person designing the circuit to make sure the appliance operates without tripping.

The maximum, I would assume is to keep the appliance/cable operating within safe limits.

Not having the oven or microwave yet means I can't check what cable they supply.

Edit...

My problem is, running 2 dedicated 16amp supply's, as well as other supply's just for a tiny kitchen (70s house only 1 ring final) just seems bonkers.