Electric oven install needs FCU?

[deko]

Hello,

The age old question of how to connect an electric oven arises again.
So let me first begin with a picture, my current cooker circuit setup...

(Sorry about orientation, I took the picture the right way up?)

Starting at the consumer unit, I have a 32A breaker protecting a radial circuit wired in 6mm cable, via an isolator switch (no additional 13A socket) to a cooker connection unit. A single socket to power the gas hob ignition is spurred off of the ccu.

The oven is the Miele H2561 BP, max load 3.6kW, and came with a pre-installed flex and the following instructions...

"Connection of this appliance should be made via a fused connection unit or a suitable isolator."

The flex looks to be 1.5mm.

So obviously changes need to be made. Now before going any further, I'd just like to mention that in order to make both the fuse in the fcu and the fuse in the plug (for the hob ignition) accessible without having to pull out the oven, I'm going to have to install new components in the adjacent cupboard. Not my preference, but I just don't have the necessary clearance from the hob above.

I have a few questions on this, so it'll be easier if I assign them numbers.

1. The Cooker Connection Unit
Should I stay or should I go?
I was thinking of leaving it as is, disconnecting the 13A socket and extending the circuit by running some 6mm through to the back of the cupboard on the left and connecting to a FCU inside there.

2. The FCU
The max load on the oven is 3.6kW (15.65A).
Taking into account diversity results in 11.70A.
So I'm thinking a 13A FCU will do the job. However the oven specs on the website (not in manual) suggest a fuse rating of 16A. Should I be concerned?

3. The 13A socket for hob ignition
As I mentioned earlier, I'd like to make the plug for the hob ignition accessible so I can change the fuse if it blows. So was planning to move it into the cupboard alongside the FCU.
Assuming the FCU has 6mm cable coming into the supply side, will I be able to run a spur in 6mm to the socket using the same terminals?
Or would I be better off running some 2.5mm from the load side of the fcu to the socket. Bearing in mind the flex for the oven will be connected to the load side also. The flex is crimped at the ends.
Is there another better way altogether?

4. Components in the cupboard
If everything above is ok, will it be easy enough to run 6mm cable and flex to the fcu directly through the back of the backbox, so no cables are showing in the cupboard (aside from the hob plug and flex of course). Will the layout of the box allow that route or will it be too awkward?
Will I need an extra deep backbox?

I think that about covers it.
Any advice welcome.

Thanks
d.

 

[endecotp]

It says "or a suitable isolator". Why do you think your current isolator is unsuitable?
I think you should just wire the new oven into the existing connection unit.

 

[winston1]

Another manufacturer who does not know what he is talking about. Yon can't get 16 amp fuses for 13 amp FCUs. Miele, a foreign manufacturer, does not seem to know FCUs are not available or compliment in the majority of the its markets.

 

[EFLImpudence]

Starting at the consumer unit, I have a 32A breaker protecting a radial circuit wired in 6mm cable, via an isolator switch (no additional 13A socket) to a cooker connection unit. A single socket to power the gas hob ignition is spurred off of the ccu.

Just right.

The oven is the Miele H2561 BP, max load 3.6kW, and came with a pre-installed flex and the following instructions...
"Connection of this appliance should be made via a fused connection unit or a suitable isolator."
So obviously changes need to be made.

Why?

Now before going any further, I'd just like to mention that in order to make both the fuse in the fcu and the fuse in the plug (for the hob ignition) accessible without having to pull out the oven, I'm going to have to install new components in the adjacent cupboard. Not my preference, but I just don't have the necessary clearance from the hob above.

Don't do it, then.

However the oven specs on the website (not in manual) suggest a fuse rating of 16A. Should I be concerned?

Are you sure it does not say it should be on a 16A supply? There are no 16A fuses.

3. The 13A socket for hob ignition
As I mentioned earlier, I'd like to make the plug for the hob ignition accessible so I can change the fuse if it blows. So was planning to move it into the cupboard alongside the FCU.

Has it ever blown? Why would it?
The oven slides out after removing two or four screws.

I think you should just wire the new oven into the existing connection unit.

So do I.

 

[deko]

It says "or a suitable isolator". Why do you think your current isolator is unsuitable?
I think you should just wire the new oven into the existing connection unit.

I'm ok with the isolator, it's the bit about the fcu that I was drawing attention to. Sorry, should have deleted that bit from the quotes.
The flex attached to the oven looks to be 1.5mm, forgot to mention that originally, just edited original post.
Is there not a danger of this flex overheating if connected directly to the existing connection unit, given that the circuit is on a 32A breaker?

Another manufacturer who does not know what he is talking about. Yon can't get 16 amp fuses for 13 amp FCUs. Miele, a foreign manufacturer, does not seem to know FCUs are not available or compliment in the majority of the its markets.

My first assumption was that they expected me to downgrade the 32A breaker to a 16A in the CU. I guess this is one way to do it, but I was thinking if I get a different oven in the future then I may need to change the mcb back to 32A. It'd make more sense to insert a 13A FCU into the existing circuit and if not needed in future, remove it and connnect directly to ccu.

Are you sure it does not say it should be on a 16A supply? There are no 16A fuses.

Exact wording from web site specs, "Fuse rating in A -- 16".
No mention of 16A supply.

Has it ever blown? Why would it?
The oven slides out after removing two or four screws.

Just being over cautious I guess. Never had a mains powered hob ignition before .
If they're not known for blowing fuses then I'd be happy to leave the socket where it is and pull out the oven if there are any issues.
That would mean the only problem left is whether to FCU or connect directly.

Thanks all
d.

 

[EFLImpudence]

Exact wording from web site specs, "Fuse rating in A -- 16".
No mention of 16A supply.

Fair enough.

There is no mention (I don't think) of fusing in the actual manual - page 92
https://www.miele.co.uk/pmedia/ZGA/TX3587/10168910-000-03_10168910-03.pdf

although they do mention FCU - which they don't have in Europe.

whether to FCU or connect directly.

Connect directly.

Is there not a danger of this flex overheating if connected directly to the existing connection unit, given that the circuit is on a 32A breaker?

No, it doesn't work that way round.
The oven can only draw what it needs.

My first assumption was that they expected me to downgrade the 32A breaker to a 16A in the CU. I guess this is one way to do it, but I was thinking if I get a different oven in the future then I may need to change the mcb back to 32A. It'd make more sense to insert a 13A FCU into the existing circuit and if not needed in future, remove it and connnect directly to ccu.

I disagree. Much easier to change the breaker (and back) than alter the accessories.

 

[deko]

Before starting this thread, I did what I thought was the right research.
Now, I think the whole "FCU" was just a distraction, and a better approach would have been to focus the search on "16A oven".
That returned a heap of results referencing these '16A european ovens'.

Some people are still wiring via 13A FCU's and some are using 13A plugs.
However some ovens may draw more than that when in pyrolitic cleaning mode.
Which could mean there's a chance you'll be changing those 13A fuses from time to time.

So in summary, the best approach for me is to...

1. Leave the current CCU and socket in place.

2. Hardwire the oven into the CCU.

3. To keep in line with the manufacturers recommendations of a 16A fuse, de-rate the 32A radial to a 16A radial by changing the mcb in the consumer unit.

4. Don't worry so much about the 3A fuse blowing on the hob ignition (if it does just pull out the oven to inspect).

For anyone reading this in the future, I think the following is the most concise thread...

//www.diynot.com/diy/threads/wiring-up-a-16a-3-1kw-oven.345627/

A big thanks to EFLImpudence for that one too

d.