I will soon be routing cables for my kitchen re-furb and wondered about
the
best practice here. This is an extension with solid floor so all cabling
routed in loft then drops to fittings etc.

Personally, I routed the cables horizontally in the kitchen (it's basically
the only time I would consider horizontal shallow buried unprotected runs).
The sockets come thick and fast and are horizontally adjacent. It saves a
lot of cable and means you don't run into total ring length issues which can
quickly come up if you are using 4m per socket drop plus the distance
between.

Christian.

Hi all

I will soon be routing cables for my kitchen re-furb and wondered about the
best practice here.
This is an extension with solid floor so all cabling routed in loft then
drops to fittings etc.
Currently cables are clipped neatly to joist sides in loft space and pass
through drilled holes when running perpendicular to joists.
This obviously means that when I re-insulate with 100mm or more, the cables
are buried and need down rating accordingly.

In new installs, is this insulation issue considered i. e. are cables
trailed across the joists with insulation pushed underneath.
Any recommendations on best practice appreciated, bearing in mind BCO
involvement and Part P of course!


TIA

Phil

On Fri, 10 Mar 2006 11:50:38 -0000, Christian McArdle wrote:

Personally, I routed the cables horizontally in the kitchen

Me too, but I think the OP was more concerned about the loft. Put the
insulation under the cables, cut a channel in it if required.

--
Nigel M

On Fri, 10 Mar 2006 12:15:25 -0000, TheScullster wrote:

but I am considering separating these [rings].

Don't consider it, do it.

--
Nigel M

"Christian McArdle" wrote

Personally, I routed the cables horizontally in the kitchen (it's
basically
the only time I would consider horizontal shallow buried unprotected
runs).
The sockets come thick and fast and are horizontally adjacent. It saves a
lot of cable and means you don't run into total ring length issues which
can
quickly come up if you are using 4m per socket drop plus the distance
between.

Good point, what is the length limit for 2.5 T&E ring circuit?
At the moment, the kitchen is just an extension of the downstairs ring, but
I am considering separating these.

Phil

At the moment, the kitchen is just an extension of the downstairs ring,
but
I am considering separating these.

No need for consideration. Anything else is unacceptable. I actually have 3
different socket circuits in my kitchen. One general purpose. One
fridge/freezer only, to reduce the risk of food spoilage. Finally, one for
laundry appliances and dishwasher so there are no heavy loads on the general
purpose ring.

Christian.

TheScullster wrote:

Good point, what is the length limit for 2.5 T&E ring circuit?

That depends...

-----------------------------------------------------------------
Max. cct. lengths for 30/32A ring circuit using 2.5mm^2 T&E cable
================================================== ===============
Earthing type
Overcurrent device Rating TN-S PME
------------------------- ------ ---- ----
Cartridge fuse (BS 1361) 30 A 90 m* 90 m
Rewireable fuse (BS 3036) 30 A 91 m** 91 m
MCB Type B (BS EN 60898) 32 A 88 m 88 m
MCB Type C (BS EN 60898) 32 A n/a 76 m
================================================== ===============
Notes: * - requires R2/40.3 ohm, reg. 413-02-12
** - requires R2/40.36 ohm, ditto
n/a - not allowed, earth fault loop impedance too high.

(R2 is the resistance of the CPC, measured round the ring.)

See Table 7.1 in the OSG for more detail.

--
Andy