Hi all

Just out of interest really..............
A colleague recently bought a new Barratt house and one or two things were
puzzling me.
The house is split over three floors being one of these trendy "town-house"
style buildings.
He showed me the electrical inspection document which lists the circuits,
protection measures etc.
There are 2 lighting circuits, ground floor then first-and-second floor.
Each of these was labelled as run in 1.0mm2 with a 1.0mm2 cpc. I thought
that the use of 1.0mm had been dropped, or was it just the stuff with a
0.75mm2 cpc?
Second question..........
In his kitchen there is a panel of grid type switches which isolate the
below-worktop sockets for washer/dryer, fridge etc.
This implies that principle power users are all tapped-off the same point on
the ring - I thought that this was generally to be avoided.
From memory I don't think the kitchen had a separate ring although the same
argument would apply either way.

Any comments appreciated

Phil

On 2007-12-30 17:34:54 +0000, "TheScullster" said:

Hi all

Just out of interest really..............
A colleague recently bought a new Barratt house and one or two things were
puzzling me.
The house is split over three floors being one of these trendy "town-house"
style buildings.
He showed me the electrical inspection document which lists the circuits,
protection measures etc.
There are 2 lighting circuits, ground floor then first-and-second floor.
Each of these was labelled as run in 1.0mm2 with a 1.0mm2 cpc. I thought
that the use of 1.0mm had been dropped, or was it just the stuff with a
0.75mm2 cpc?

1mm^2 seems to be the common lighting size.


Second question..........
In his kitchen there is a panel of grid type switches which isolate the
below-worktop sockets for washer/dryer, fridge etc.
This implies that principle power users are all tapped-off the same point on
the ring - I thought that this was generally to be avoided.
From memory I don't think the kitchen had a separate ring although the same
argument would apply either way.


It can still be part of the ring.

The arriving cable goes to switch1, then 1 goes to 2, 2 goes to 3, 3
goes to 4,.... until the last one where the departing cable is
connected. It's still a ring, but the wiring accessories are simply
very close together. It would be a problem if the arriving and
departing cables both went to 1 and then 2,3,4 were connected to that
as well at a single point. However, the conductors probably wouldn't
fit in the terminals of 1 since there would be 5 in this example.
Maintain the architecture of the ring and it's two as normal. There
isn't anything specificying the minimum distance between wiring
accessories on the ring as long as they part of it, AFAIK.

"Andy Hall" wrote in message news:4777dddf@qaanaaq...
On 2007-12-30 17:34:54 +0000, "TheScullster" said:

Hi all

Just out of interest really..............
A colleague recently bought a new Barratt house and one or two things
were
puzzling me.
The house is split over three floors being one of these trendy
"town-house"
style buildings.

Reminder to self: Must get shares in stairlift companies.

TheScullster wrote:

There are 2 lighting circuits, ground floor then first-and-second floor.
Each of these was labelled as run in 1.0mm2 with a 1.0mm2 cpc. I thought
that the use of 1.0mm had been dropped, or was it just the stuff with a
0.75mm2 cpc?

1mm CPCs were phased (pun not intended) out on 2.5mm^2 T&E power cables
since it was not always effective under fault conditions with 30+A
protective devices.

For lighting circuits protected at 6 or 10A, a 1mm^2 CPC is fine (and
normal for 1mm^2 T&E cable)

Second question..........
In his kitchen there is a panel of grid type switches which isolate the
below-worktop sockets for washer/dryer, fridge etc.
This implies that principle power users are all tapped-off the same point on
the ring - I thought that this was generally to be avoided.
From memory I don't think the kitchen had a separate ring although the same
argument would apply either way.

Much would depend on how they wired it.... but you are right, it could
be a bit dodgy. You could do it use a lighting style "loop in wiring"
on the sockets. The difficulty there being you would need a pair of
switch drop wires per socket to give you proper isolation switching
since you need to break both poles. Using a single wire would only break
the live to each socket.

Taking the face plate off one of the appliance sockets would probably
tell you. A single cable would indicate they had done what you suspect.

--
Cheers,

John.

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"Owain" wrote


However, the circuit might also be a radial, in which case I hope it's a
30A one in 4mm

Owain

The circuit according to the spec is fed with 2.5mm cable so I assume it's a
ring.

Phil

"Dave Plowman (News)" wrote

I doubt it
would make much difference in practice if they were all high loads given
the switch panel is likely to be near the centre of the ring, if the CU is
at the front door as in most new builds.


Good point Dave

scullsterhome wrote:

The circuit according to the spec is fed with 2.5mm cable so I assume it's a
ring.

The Schedule of Test Results should positively identify all/any ring
circuits as such (in column 8, under the heading of "continuity" if
forms based on the standard model have been used).

--
Andy