On 14 Jan 2004 21:25:14 GMT, wrote:

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

To summarise - the oven is rated at 5.18kW (22A @ 230v) (double under
counter oven) and the hob at 5.4kW (23A @ 230v).

[ ... ]

This cannot be an uncommon application, but what is the best way to proceed,
with the regulations.

BTW the CU is only a few metres from the oven hob, max 4m or cable from CU
to DP switch then 1m to the appliances.


The Regs allow you, sensibly, to treat the hob + oven as comprising a
single cooking appliance, to which you apply standard Domestick diversity
rules for a cooker. The combined Hamperage from your ratings is 45A.
The Diversity allowance for domestic use is "10A + 30% of the rest
+5A if you've a socket on the control panel". In your case, ass-U-ming no
such socket, the diversity-corrected load is (10 + 35*0.3) = 20.5A.
Thus it's well within Regs to use a single circuit, with a 32A MCB,
wired in 6mmsq as far as the switch (4mmsq kind-of OK on short run without
thermal insulation, but don't arse about, use 6mmsq). From the DP switch
make the connections to the hob and oven in 2.5mmsq if you already have it,
or 4mmsq if you're buying new (might as well allow for the odd Christmas
lunch peak load).

I do hope your hobnoven come with thermally resistant oversleeving for the
L and N conductors where they're connecting in to the hob, though - it
does get warm in these appliances (no s**t Sherlock ;-) and plain PVC
gets soft and less useful at higher temps (70C upwards is the usual guide)...

HTH - Stefek

Have you ever wired anything up before. Stating regulations willy
nilly does not constitute a safe and constructive answer to help the
OP along. If I came across a cooker and hob wired the way you suggest
I would probably condemn the whole installation on the grounds anyone
who plays around with one part of the electrical installation
regardless of knowledge or competence will probably have had a go at
the rest of the wiring.
It's generally not good practice to run multiple supplies from one
isolator, especially without providing any protection in the way of
upstream CPD's.


SJW
A.C.S. Ltd.