Allowable Cooker Connection Unit outlet plate positions behind built-in oven?

[BobT007]

Query regarding the position of the oven cooker connection outlet behind the oven, and its implications.
(Sorry bit long, but a number of overlapping questions in my head about this.)

My oven installation instructions shows a diagram with a hatched area and states “the mains socket for the appliance must either be located in the hatched area (a) or outside the area where the appliance is installed” - see diagram:

(Note: This is a Bosch 2.99 kW oven requiring to be hardwired with 13A fuse protection. So rather than a normal Cooker Connection Unit / Cooker Cable Outlet connection I probably need to use (?) a Fused Connection Unit with Flex Outlet with 13A fuse instead, to satisfy the oven fuse protection specs.)


Do you know, is this location specification an electrical issue (maybe related to heat issues caused by proximity behind the oven?) or simply to do with the physical dimensions of the oven, that may not allow the physical space to put a connection outside the hatched area?

For instance, if installing the oven in a cabinet with the minimum dimensions shown in the instructions (see diagrams below), the back of the oven (which bulges out horizontally across approx. 2/3 of the rear on the left side, and approx. the top 3/4 vertically) would almost touch the back wall/panel, so in the area behind the bulge of the oven there would physically not be any room for an outlet.

One of the reasons I am querying this is that, according to my careful measurements, (neither my fitted kitchen oven housing cabinet unit nor the oven are in place yet, so just measurements so far), it looks like the Cooker Connection Unit / Fused Connection Unit (the back box position is already fixed) will be fully within the hatched area horizontally, BUT not fully within vertically - the top of the CCU / FCU will have around 20mm poking out of the top of the hatched area, but still clear of the oven rear bulge, and with (relatively speaking) plenty of space all around the CCU/FCU because my kitchen oven cabinet unit is 20mm deeper than the minimum specified in the installation diagrams (so CCU/FCU would be about 50mm away from the non-bulged part of back of oven).


So, recapping:

1. I am thinking the instruction regarding the "mains socket" location having to be in the hatched area is simply to do with the space needed to fit the outlet, rather than possible heat issues affecting the electrics etc., but am interested in the opinions of those with more experience with this kind of thing.

2. generally, do you know what kind of heat exposure Cooker Cable Outlet plates, and Fused Connection Units (and the ‘standard wiring’ that may be inside them coming from the consumer unit) can tolerate? Is there an official safety specification for such fittings with regards heat tolerance?

3. And, whatever the actual reason is for this precisely defined hatched area (perhaps they are just being helpful and saying ‘this is the area where there will definitely be enough space’!) does anyone know if manufacturers (Bosch in this case) would make a big deal of it, if something went wrong and your Cooker Connection was not fully within this specified "hatched area"!?


If you are still reading! Thanks,

 

[AndyPRK]

More to do with the lump on rear of oven and heat.

Surprised it doesn’t come with a plug.

 

[BobT007]

More to do with the lump on rear of oven and heat.

"... and heat" or "than heat" ?

 

[EFLImpudence]

"... and heat" or "than heat" ?

Could be either. Above the lump might be too hot.

 

[AndyPRK]

AND Heat.

Don't want to get the fuse any hotter than necessary.

I fitted an AEG cooker, and the instructions located certain external surfaces would be hot. (near elements i expect)

Heat rises, so that location at the bottom seams sensible

 

[BobT007]

Don't want to get the fuse any hotter than necessary.

So, if there might be a heat issue, would you perhaps be inclinded to fit a normal cooker connection unit behind oven, and fit in a fused connection unit with 13A fuse (for the specified fuse protection requirement) somewhere else between cooker connection unit and consumer unit?

 

[AndyPRK]

If they have said to put the "the mains socket" in hatched area, then they will have tested that, and satisfied themselves its ok.

Have you purchased the oven yet? It seam's to suggest it comes with a plug, and you need to fit a socket. In which case you fit a socket
As heat rises it should be ok down there.

I wouldn't go fitting an extra 13A fuse. Waste of time and extra connections to fail.
A 32A MCB will probably trip before a 13A fuses will blow

 

[AndyPRK]

Do you have an existing CCU behind the oven ?

 

[BobT007]

Have you purchased the oven yet? It seam's to suggest it comes with a plug, and you need to fit a socket. In which case you fit a socket
As heat rises it should be ok down there.

Yes, purchased, Bosch HQA574BS3B ("Connection rating 2990 W", "Plug type - no plug (electrical connection by electrician)", "Fuse protection 13A")

Do you have an existing CCU behind the oven ?

Just starting kitchen re-fit - behind planned new oven position is old back box (no CCU fitted), with 2.5mm2 wiring from there to DP isolation switch on wall, and from there 2.5mm2 back to consumer unit.

(and as mentioned above, the back box position is almost entirely within the hatched area (according to my measurements) but not fully, with top approx. 20mm may be 'sticking out' top of hatching, but back box location is certainly clear of the bulged area of the oven rear, which is on left 2/3, and back box is in the right 1/3)

 

[AndyPRK]

What size mcb is in the CU for cooker

 

[BobT007]

What size mcb is in the CU for cooker

Well, it was going to a 32A, but connection at CU has been disconnected (didn't even realise, but must have been disconnected when electricians were round doing some new cabling a while back), so could be reconnected to whatever MCB size is best - 16A, 20A, ... ?

 

[AndyPRK]

Yeah with 2.5mm cable you want 16 or 20.

Then just connect the oven up to the CCU and don’t worry about it

 

[ebee]

Heat rises

We were chastised at shool for saying "Heat Rises" it`s not the heat that rises it is the hot air (or onther gases) that rise because they are hot.
Conduction/Convection/Radiation .
Actually we were taught about "Centrifugal Force" back in those days too - apparently it no longer exists!

 

[XrayDave]

We were chastised at shool for saying "Heat Rises" it`s not the heat that rises it is the hot air (or onther gases) that rise because they are hot.
Conduction/Convection/Radiation .

Actually we were taught about "Centrifugal Force" back in those days too - apparently it no longer exists!

Quite right (bit in red). It is the medium - be it a liquid like water or a gas like air - that moves upwards (because it is less dense) whillst the coder (more dense fluid - be it liquid or gas) falls. Incidentally, this wouldn't happen at all if it wasnt for gravity.

[Bit in blue] Cenrifugal force never existed - it is what people (incorrectly) call the force they feel which stops them flying off at an angle. The correct force (or at least force name) is centrepetal (means centre-seeking). It is all to do with your frame of reference.

If you are observing a rotating system from the outside, you see an inward centripetal force acting to constrain the rotating body to a circular path.

However, if you are whirling around on a inside the ride, you experience an apparent centrifugal force pushing you away from the center of the circle. What you are feeling is the inward centripetal force that is keeping you from going off on a tangent.

This is a similar misunderstanding like when you are pushing against a wall. You are aware of the force you are putting on the wall, but you aren't aware of the same force (but in the opposite direction) being applied to you by the wall (this is because the wall 'bends' and pushes back on you in the same way that when you pull on a bowstring, you can feel the bowstring pulling on you). Hard concepts to get your head around.

Whoever said Physics was simple?!

XRD

 

[ebee]

Hmm - I gathered the "Force" was by an attempt for things to stay as were unless some force acting somewhere , which I think tallies with the piece of string idea as you spin things around, same thing I thinks (in part) but you have put it ever so eloquently than I.

The good thing is, the "laws" or rules we learned to apply tend to hold true enough for most use anyways (good luck I think) so we can still talk about it existing even though it actually does not.

Electrons no longer flow the way they used to do - well maybe they did but we guessed it wrong therefore we adopted the wrong guess as if it was actually fact.