I'm currently upgrading a kitchen by replacing a freestanding gas oven
(at the end of a run of kitchen units) with a built-under gas oven and
hob, plus a cooker hood, and fitting new worktop. I need to run some
lecky behind the new oven housing, to power the two gas igniters and the
cooker hood, and for that I'm proposing to hijack the existing
(redundant) radial cooker circuit, which comes down from the ceiling -
ie, an FCU for the cooker hood behind its s/steel chimney, with a cable
drop straight down to a double 13A socket behind the oven.

First, is there anything wrong with that scheme wiring-wise? (BTW I'm
not concerned about preserving the cooker circuit for potential future
use with an electric oven.)

Secondly, what are the regs about accessibility of the FCU and the 13A
socket? Is it a 'nice-to-have' or is it compulsory that they can be
accessed easily to isolate the relevant appliance? Thing is, in this
case it would be really pretty awkward to achieve this - I don't want to
have to disturb the rest of the kitchen, and because the extractor
will sit on a narrow stretch of wall spanning the back door and a
window, there's nowhere obvious to fit a switch that wouldn't look crap.

In the case of the oven housing, I hope there might be space at the back
to make an access hole in one side, to enable a hand to reach in from
the adjacent unit to the 13A socket; however I won't know until the
appliance is delivered (and I need to finalise the wiring the same day...)

Thanks!
David

Lobster said the following on 01/11/2005 23:49:
I'm currently upgrading a kitchen by replacing a freestanding gas oven
(at the end of a run of kitchen units) with a built-under gas oven and
hob, plus a cooker hood, and fitting new worktop. I need to run some
lecky behind the new oven housing, to power the two gas igniters and the
cooker hood, and for that I'm proposing to hijack the existing
(redundant) radial cooker circuit, which comes down from the ceiling -
ie, an FCU for the cooker hood behind its s/steel chimney, with a cable
drop straight down to a double 13A socket behind the oven.

First, is there anything wrong with that scheme wiring-wise? (BTW I'm
not concerned about preserving the cooker circuit for potential future
use with an electric oven.)

No problem, however the cooker feed will probably be 6 sq mm protected
by 30/32A device, so if you want to do the new bits of the wiring in 2.5
sq mm, reduce the size of the protection device (i.e. fuse or MCB) in
the consumer unit to 20A (or less).


Secondly, what are the regs about accessibility of the FCU and the 13A
socket? Is it a 'nice-to-have' or is it compulsory that they can be
accessed easily to isolate the relevant appliance? Thing is, in this
case it would be really pretty awkward to achieve this - I don't want to
have to disturb the rest of the kitchen, and because the extractor will
sit on a narrow stretch of wall spanning the back door and a window,
there's nowhere obvious to fit a switch that wouldn't look crap.

The wiring regs 553-01-06 specifies that "a socket outlet on a wall ...
shall be mounted above ... any working surface to minimize the risk of
mechanical damage to the socket outlet or its associated plug and its
flexible cord ..."

Approved document M of the building regs covers accessability also, but
it looks like it would not apply to these outlets in a kitchen.

Generally speaking, it is good practice to make allowance for
maintenance and isolation and you should make a reasonable effort to
make access straighforward if not exactly simple.

In the case of the oven housing, I hope there might be space at the back
to make an access hole in one side, to enable a hand to reach in from
the adjacent unit to the 13A socket;

Sounds good. Don't be tempted to affix the socket outlet/fixed wiring
to the carcass of the kitchen units/oven housing - this is considered
cowboy practice (although kitchen fitters do it all the time!).

HTH

"Lobster" wrote in message
...
I'm currently upgrading a kitchen by replacing a freestanding gas oven
(at the end of a run of kitchen units) with a built-under gas oven and
hob, plus a cooker hood, and fitting new worktop. I need to run some
lecky behind the new oven housing, to power the two gas igniters and the
cooker hood, and for that I'm proposing to hijack the existing
(redundant) radial cooker circuit, which comes down from the ceiling -
ie, an FCU for the cooker hood behind its s/steel chimney, with a cable
drop straight down to a double 13A socket behind the oven.

First, is there anything wrong with that scheme wiring-wise? (BTW I'm
not concerned about preserving the cooker circuit for potential future
use with an electric oven.)

Secondly, what are the regs about accessibility of the FCU and the 13A
socket? Is it a 'nice-to-have' or is it compulsory that they can be
accessed easily to isolate the relevant appliance? Thing is, in this
case it would be really pretty awkward to achieve this - I don't want to
have to disturb the rest of the kitchen, and because the extractor
will sit on a narrow stretch of wall spanning the back door and a
window, there's nowhere obvious to fit a switch that wouldn't look crap.

In the case of the oven housing, I hope there might be space at the back
to make an access hole in one side, to enable a hand to reach in from
the adjacent unit to the 13A socket; however I won't know until the
appliance is delivered (and I need to finalise the wiring the same day...)

Thanks!
David

means of isolation must be easily accessible with the appliance fitted and
must be double pole, a switch on a socket outlet is not suitable, within
2mtrs in the case of a cooking appliance.

Rumble wrote:

snip advice

Thanks a lot for that, much appreciated.

In fact today's investigations things have changed a bit today having
started the work; in that I've found a ring main inside some boxing
which I can tap into and extend the ring main; a better result really.
(Unfortunately the cooker circuit had to go anyway, as it ran neatly
through the middle of the hole in the wall for the extractor!)

I've decided to address the 'access to the cooker hood power' issue by
fitting a switched, DP, FCU into the ring main; it will sit just to the
left of the s/steel chimney. However, unless I don't mind
surface-mounted wiring (and I do) I'm not clear the flex inside the
cooker hood should be connected to the FCU. The easy way would be to
run the flex under 6" of horizontal, buried capping between chimney and
FCU, but you aren't supposed to bury flex, are you? It still seems to
me the best way, as it avoids any electrical junctions within the steel
chimney (and the flex is only 2-core with no earth provision, which
seems very odd to me.) The other way would be to put a non-switched FCU
within the chimney, and have a DP switch outside, however there's
defintely not room for that within the very short chimney.

So what do I do?!

David

powerstation wrote:

means of isolation must be easily accessible with the appliance fitted and
must be double pole, a switch on a socket outlet is not suitable, within
2mtrs in the case of a cooking appliance.

Thanks - I'd planned on having a DP double socket outlet behind the unit
for the igniters; surely that's OK isn't it?

David

Lobster said the following on 02/11/2005 18:52:
Rumble wrote:

snip advice

Thanks a lot for that, much appreciated.

In fact today's investigations things have changed a bit today having
started the work; in that I've found a ring main inside some boxing
which I can tap into and extend the ring main; a better result really.
(Unfortunately the cooker circuit had to go anyway, as it ran neatly
through the middle of the hole in the wall for the extractor!)

I've decided to address the 'access to the cooker hood power' issue by
fitting a switched, DP, FCU into the ring main; it will sit just to the
left of the s/steel chimney. However, unless I don't mind
surface-mounted wiring (and I do) I'm not clear the flex inside the
cooker hood should be connected to the FCU. The easy way would be to
run the flex under 6" of horizontal, buried capping between chimney and
FCU, but you aren't supposed to bury flex, are you? It still seems to
me the best way, as it avoids any electrical junctions within the steel
chimney (and the flex is only 2-core with no earth provision, which
seems very odd to me.) The other way would be to put a non-switched FCU
within the chimney, and have a DP switch outside, however there's
defintely not room for that within the very short chimney.

So what do I do?!

David

Well, Firstly, you shouldn't really bury the flex from the cooker hood,
because (unless you can disconnect the flex at the cooker hood end), you
would have to dig the plaster out to remove the cooker hood for
maintenance or repair.

Secondly, the fact that the flex from the cooker hood is only two core
means that the internals of the unit are double insulated (Class II).
Exposed metal parts should *not* be separately earthed unless
specifically mandated in the installation instructions.

Thirdly, unless otherwise mandated by the instruction manual, there is
no need to provide an isolating switch for the cooker hood; an
unswitched FCU (with appropriate fuse) will give adequate protection
against fire and shock.

Fourthly, again unless otherwise mandated by the instruction manual,
there is no need to provide an isolation switch for the ingiter/clock
circuits for the gas hob and oven, provided you make the socket outlet
reasonably accessible (so you can isolate by pulling the plug).