In uk.d-i-y, Gary wrote:

So you advise to wire from the DP switch in 2.5mm cable even though the
whole circuit is backed up by a 32A MCB?
Don't play with something you know nothing about.

"Advise" is over-strong, but it's both within the letter of the regs and
consistent with safe procedure. The two partloads are - if you read the
poster's original query - each going to draw no more than 24A (10 of your
best British keelowatts); and that's only under peak conditions when all
4 themostats/simmerstats on the hob cut in at once, or when both ovens
have their element thermostats switched on (e.g. when warming up) and
their fancy-dancy side-mounted auxilliary browning elements switched on
(or whatever else is in there to get the full load up to 10kW). Like I
said, if buying new anyway then 4mmsq would give a bigger margin for
safe operation; full paranoia would be 6mmsq all the way through, Just
In Case some other occupant at a later date decided to attach an all-in-one
older-style freestanding cooker to just one arm of the circuit beyond
the DP switch; but 2.5mmsq for the short (earth loop impedance considerations)
downstream sections to separate hob & oven *is* permissible, safe, and
practised, where the loads are as the original poster described.

These are thermostatically controlled loads, which have no way of causing
an overload beyond the rated power, and even in "full" use draw well under
the full rated power when considered over timescales of minutes: very
different from either a socket circuit, where multiple unknown loads can be
plugged in, or motor circuits where a stall or excess mechanical load can
cause a higher current to flow for a sustained period. And in just such
cases, the Regs foresee and allow for - and qualified penny-penching
circuit design engineers looking to cut another 60p off the materials
costs for the next Barratt box take full advantage of - sizing of conductors
according to the peak load, rather than according to the protective device.
You may not find it pretty; you may argue that it's cutting close to the
edge; and that it's a safe simplification to adopt the simpler principle
"all conductors should be capable of carrying for an indefinite period the
nominal current of the protective device" (In in Regs-speak). But that's
*not* the full story on either what the Regs say or what economical
engineering practice does to balance cost against compliance; and the
tweaks about "nature of the load" allowing sizing by design current rather
than nominal are used internally in equipment wiring (you don't think those
hob elements have 6mmsq conductors leading to them, do you?), and in the
widespread Continental practice of 0.75mmsq appliance flex, unfused,
connecting into 16A radial circuits with no closer fusing, as well as this
particular case of splitting out feeds to Modern Kitchen Hob-n-Oven
splitlevel units.

Still, don't mind me: I probably don't know what I'm talking about; and
probably never wired nuttin'...

Stefek