As part of the planning for my new kitchen, I looked at the current layout
today. I would have helped my dad to rewire it but Part P seems to have put
paid to that. I would still like to know what to ask the electrician and
get an idea of what he will do. I've done plenty of searching on here and
found lots of useful information but not everything yet.

As is usual for a 70s two-bed semi, the current layout is inadequate and in
my case badly altered by previous owners. The house has a single ring main
with a 32A MCB and cooker radial also with 32A MCB.

The kitchen has two single sockets above the worktop on the ring, one each
side of the hob. From one, a spur cable runs diagonally unshielded under
the plaster to the cooker hood, with no form of isolation! The other single
socket has a spur cable going to a socket under the worktop, itself having a
spur cable along the floor to a small CU with RCD under the sink for
powering the garden circuit. The cooker outlet (with socket) supplies the
electric oven and igniter for the gas hob.

Obviously the diagonal hood cable is a no-no but I was wondering how the
cable(s) to the hood could be run. Dropping from the ceiling, as the two
sockets above the worktop are wired, would be feasible but where could an
isolation switch go? I wouldn't want it behind the chimney. How is it done
from below? Keeping to the vertical/horizontal from an accessory rule, a
cable dropped vertically from the hood could necessitate an accessory behind
the hob? I won't be having units on either side of the extractor. Is
putting the cable in metal conduit, a switched FCU to one side of the hob
and unswitched outlet behind the hood the best method?

Under Part P, must the approved person do absolutely everything? If I left
some nicely chased walls in the (to be) gutted kitchen, where the
electrician would want them, I gather he could use them? To save on
expensive electrician's time and cost, it would make sense to do as much
prep work as possible. Where does Part P draw the line on what is
electrical? Could I put back-boxes in?

I expect a new ring main to supply the kitchen would be desirable. The
kitchen items on the ring would take a dishwasher, fridge freezer, combi
microwave, gas hob, extractor and kettle. The washing machine and tumble
drier are in the downstairs loo - but that's another wiring issue.

I expect an electrician would route the cable along the wall in the adjacent
integral garage containing the consumer unit. Since the cable would not be
coming from the ceiling, would it be acceptable to run cables on the surface
(in trunking if necessary) in the void behind base units? This would be on
the right level for the hob and dishwasher outlets (accessed from units to
the side of these).

Even if the wall was chased horizontally on the line of the above-worktop
sockets, how would the dishwasher cable be dropped? The dishwasher will be
midway between the cooker and sink-drainer, with the outlet under the
drainer. Could the cable do a right angle above the drainer, in the
horizontal plane of the above-worktop sockets and vertical plane of
dishwasher outlet, even though there is no visible accessory at the point of
the right-angle?

Would the following be a valid new ring layout, with S being a switched
socket, the bottom two being for the dishwasher (right) and hob (left)
mounted under the worktop in accessible cupboards. Everything else is
above. The rough location of the appliances is shown, the cooker outlet for
the oven is not. Hopefully the ASCII art is readable.


Hood---|
(m/w) (kettle) |
|
---SS------SS------SS--------FCU----SS-------|
-| (Hob) |
| (f/f) (Oven} (D/W) |
| |
|-----------------S-------------------------S


This suggestion ignores adding RCD protection. Is it especially necessary?
Is the electrician likely to suggest it?

Lastly, I need to move the garden electrics, as the CU is mounted in the
sink unit that is being replaced, and the spur socket from which it is
unsuitably wired will no longer be there. As garden wiring is notifiable,
even though it is already there, I presume I cannot do the rewiring for
that? Would the electrician consider spurring from the bottom-right S above
if he did it?

Sorry there's lots here, but thanks in advance for any helpful answers.

James