wiring for ovens etc

[finney]

I've just bought new bosch ovens etc. My problem is the instruction

have confused me.

We have a 32a fuse in the main consumer unit. this goes to a cooke isolating switch on the kitchen wall. from there one 6mm cable goes t the existing a 13a fused connection plate for the gas hob. We plan t just swap like for like. A second 6mm cable goes to another 13a fuse connection plate for the old single oven. Our new single is rated a

2.9kw and 13a so we plan to swap like for like (although with a muc longer cable as it is in another part of the room now).

Our problem is how to connect a new multi function oven. The spec i

3.6kw total connected load. Elsewhere it says it is fitted with a plu (which it isn't) and must be installed via an earthed socket with fus protection of 16a, unless the plug is not accessible then an all pol isolator must be used on the connection side. it later says in the G to permanently connect it and use the isolator.

Can I continue the 6mm cable from the single oven on to thi multifunction oven? [logistically the easier answer by far] if so ho do I achieve the 16a fuse protection? Is it ok to have both ovens o this same spur? Or should I come from the main consumer unit totall seperately using a 16a fuse there

-- finney

[Christian McArdle]

It sounds like a typical European device that would have its own 16A MCB protection at the consumer unit. Assuming you don't want to rewire in that manner,

I would suggest something like:

you've got space to mount them somewhere near the oven. Note that you also need a DP isolator. The MCB switch will meet this requirement, so you need a 20A DP switch if the cooker control unit is not close enough to the oven.

Christian.

[Christian McArdle]

Of course, i meant the MCB switch will NOT meet this requirement.

Christian.

[Dave Plowman (News)]

Yup.

Remove the existing FCU and replace it with a cooker connection unit. This is essentially a 45 amp connector block mounted on the back of a one gang plate with a cable outlet. Run 6mm cable from there to the oven. This type of oven doesn't normally have any internal or external fusing other than the main MCB.

You can also get what just amounts to a blank plate with cable outlet - designed for where you're using a continuous cable from switch to oven.

[Stefek Zaba]

Yup. Doing this means violating the letter of the installation instructions; but it's hard to conceive of this actually affecting safety materially. The fusing in the supply is to protect the cable, not the appliance: by running the cable as 6mm all the way, you're using cable which can take the nominal rating of the 32A MCB indefinitely. (Since the oven won't generate a load of more than 3.6kw = 15A@240V, you could wire its drop from the FCU in 4mmsq or even 2.5mmsq, but that would require calculations to show it's safe (they've been done here on this NG, and been so shown for 'reasonable' lengths of feed and tail; but sticking to 6mmsq keeps any 'ordinary' and/or picky NICEIC periodic-inspecting type in familiar territory...). It's *extremely* difficult to construct a plausible scenario where some appliance fault would be cleared by a 16A breaker but not a 32A one - the fault resistance would have to be unusually high and in a very precise band of values for that to happen.

Stefek