Morning all!

I'm hoping to replace a central light fitting in our kitchen by a
cluster of nine recessed LED ceiling lights and am looking for some
guidance on the best way forward.

The floor in the room above the kitchen is covered in solid laminate
so there's no easy way to lift any part of it for access to the joists
and wiring below.

I was planning to remove the existing centra light fitting and use its
mounting position and wiring to install the centre-most of the nine new
LED lights.

Running cabling ALONG between the joists around that centre light to
two more lights should be easy, but I'm wondering how I can drill the
necessary holes to run wiring sideways THROUGH the two pairs of adjacent
joists to feed the other two sets of three lights. Is it absolutely
essential to be able to lift the floor above, or cut into the kitchen
ceiling, in order to run the wiring?

Is there a 'trick-of-the-trade' or some clever (flexible ? ) device
that can be inserted through a recessed light mounting hole and allow me
to drill holes through the joists on either side for the new wiring?
Incidentally, I do have access to an 'endoscope type' TV camera that can
be inserted into a small pilot hole to look for possible obstructions.

Should I use low-voltage LED lamps or 240 volt ones - does anyone have
any recommendations on lamp styles/manufacturers/shades of white/beam
angles etc. ?

Any constructive suggestions from members of this NG will be most
gratefully received.

ATB - Dave.

In article , Dave Chapman
writes


Is there a 'trick-of-the-trade' or some clever (flexible ? ) device
that can be inserted through a recessed light mounting hole and allow me
to drill holes through the joists on either side for the new wiring?
Incidentally, I do have access to an 'endoscope type' TV camera that can
be inserted into a small pilot hole to look for possible obstructions.

Should I use low-voltage LED lamps or 240 volt ones - does anyone have
any recommendations on lamp styles/manufacturers/shades of white/beam
angles etc. ?


Not quite as scary as you might think.

Best to map out the approximate positions of your joists with a stud
finder and choose provisional positions for you downlighters.

Start cutting your holes and check with some probes (cable fishing rods
or some fence wire) that there are no obstructions and that your chosen
positions will work.

Working from your downlighter holes, probe to find the exact positions
of your joists and mark the surface. Then cut a slot in the PB or
lath/plaster just wide enough for 1.5mm2 T&E and just long enough to
bridge the joist.

Simply fish your cable through the joist bridges instead of drilling
joists. Then simply fill and finish, the T&E will be a few mm under the
surface.

Alternatively, you could cut a small notch in the bottom of the now
visible joist just big enough to accept the cable leaving a hole that a
bit of PB could be used to flush patch but I wouldn't bother as the hole
described above should be small enough for an easy fill with polyfila.

Have done this invisibly a number of times on ornate corniced ceilings.

I'll leave the recommendations on lamp types to others as I don't use
these myself.
--
fred
it's a ba-na-na . . . .

"fred" wrote in message ...
In article , Dave Chapman
writes


Is there a 'trick-of-the-trade' or some clever (flexible ? ) device
that can be inserted through a recessed light mounting hole and allow me
to drill holes through the joists on either side for the new wiring?
Incidentally, I do have access to an 'endoscope type' TV camera that can
be inserted into a small pilot hole to look for possible obstructions.

Should I use low-voltage LED lamps or 240 volt ones - does anyone have
any recommendations on lamp styles/manufacturers/shades of white/beam
angles etc. ?


Not quite as scary as you might think.

Best to map out the approximate positions of your joists with a stud
finder and choose provisional positions for you downlighters.

Start cutting your holes and check with some probes (cable fishing rods or
some fence wire) that there are no obstructions and that your chosen
positions will work.

Working from your downlighter holes, probe to find the exact positions of
your joists and mark the surface. Then cut a slot in the PB or
lath/plaster just wide enough for 1.5mm2 T&E and just long enough to
bridge the joist.

Simply fish your cable through the joist bridges instead of drilling
joists. Then simply fill and finish, the T&E will be a few mm under the
surface.

Alternatively, you could cut a small notch in the bottom of the now
visible joist just big enough to accept the cable leaving a hole that a
bit of PB could be used to flush patch but I wouldn't bother as the hole
described above should be small enough for an easy fill with polyfila.

Have done this invisibly a number of times on ornate corniced ceilings.


You do know that neither method is allowed by the regs don't you? If the OP
wishes to meet the regs then you would need the cable to be more than 50mm
from the bottom of the joists or use one of the approved cables with an
earthed metallic covering

For a little extra work the OP could cut a hole at the joist that needs to
be passed - say a 100mm diameter hole so that there is access to either side
of the joist, use a right angled drill to put a hole through the joist at
the correct height and then screw the piece of plasterboard back into place
before making good the damage.

--
Adam

On Thursday, 3 April 2014 18:46:34 UTC+1, wrote:

You do know that neither method is allowed by the regs don't you? If the OP
wishes to meet the regs then you would need the cable to be more than 50mm
from the bottom of the joists or use one of the approved cables with an
earthed metallic covering

Could you elaborate on what the regs are for ceilings Adam?

Reading from the wiki (http://wiki.diyfaq.org.uk/index.php?...and_Protection) it only makes reference to walls and partitions and is silent on the subject of ceilings (and floors too) so it could be useful to aid what is a common wiring task.

Mathew

"Mathew Newton" wrote in message
...
On Thursday, 3 April 2014 18:46:34 UTC+1, wrote:

You do know that neither method is allowed by the regs don't you? If the
OP
wishes to meet the regs then you would need the cable to be more than 50mm
from the bottom of the joists or use one of the approved cables with an
earthed metallic covering

Could you elaborate on what the regs are for ceilings Adam?

Reading from the wiki
(http://wiki.diyfaq.org.uk/index.php?...and_Protection) it
only makes reference to walls and partitions and is silent on the subject of
ceilings (and floors too) so it could be useful to aid what is a common
wiring task.


Will do a proper reply later but I am going out tonight.


The regs for cables passing through joists are very similar to cables in
walls but have no safe zone. It's reg 522.6.5 that I shall copy and paste:-)

--
Adam

On 03/04/14 20:36, ARW wrote:
"Mathew Newton" wrote in message
...
On Thursday, 3 April 2014 18:46:34 UTC+1,
wrote:

You do know that neither method is allowed by the regs don't you? If
the OP
wishes to meet the regs then you would need the cable to be more than
50mm
from the bottom of the joists or use one of the approved cables with an
earthed metallic covering

Could you elaborate on what the regs are for ceilings Adam?

Reading from the wiki
(http://wiki.diyfaq.org.uk/index.php?...and_Protection)
it only makes reference to walls and partitions and is silent on the
subject of ceilings (and floors too) so it could be useful to aid what
is a common wiring task.


Will do a proper reply later but I am going out tonight.


The regs for cables passing through joists are very similar to cables in
walls but have no safe zone. It's reg 522.6.5 that I shall copy and
paste:-)


I've got a very similar problem for my dormer roof ceiling. I might just
use steel conduit for that, buried in a layer of celotex as it will
literally be 2 straight sections screwed into a 90 bend and a besa box
on each end. The hardest part will be threading it - no bending.

The wiki does give details of how joists should be crossed, it's in the electrical installation section. A possible solution is also suggested, namely notching with the notch protected with a 3mm thick covering plate.

Richard

On 03/04/14 23:18, Tricky Dicky wrote:
The wiki does give details of how joists should be crossed, it's in
the electrical installation section. A possible solution is also
suggested, namely notching with the notch protected with a 3mm thick
covering plate.

Richard


I'm a little curious about the whole ceilings thing. I'm not going to
argue with Adam as he's a fine man who knows his area.

But - what about all those installations where lighting wiring is pulled
though end to end and left sitting on the top of the plasterboard
(because there's not enough access to clip it to the side of the
joists), ie 12mm give or take from the surface of the ceiling. It's
quite common...

On 03/04/2014 10:12, Dave Chapman wrote:

Running cabling ALONG between the joists around that centre light to
two more lights should be easy, but I'm wondering how I can drill the
necessary holes to run wiring sideways THROUGH the two pairs of adjacent
joists to feed the other two sets of three lights. Is it absolutely
essential to be able to lift the floor above, or cut into the kitchen
ceiling, in order to run the wiring?

You can do it from below...how easy it is depends a bit on the size of
the cutout you need for the new lights.

Is there a 'trick-of-the-trade' or some clever (flexible ? ) device
that can be inserted through a recessed light mounting hole and allow me
to drill holes through the joists on either side for the new wiring?

If the cutout is large enough, then you can sometimes get an angle drill
or other small drill into the hole.

e.g:

http://wiki.diyfaq.org.uk/index.php?...llation#Joists

With smaller holes you may find a flat bit and a couple of flat bit
extensions (each 12") will let you get in at a shallow angle and get a
hole into the joist each side of the hole.

The remaining way is to use an oscillating tool (or less elegantly a
widish spade bit to make some overlapping holes) to cut a rectangular
section of ceiling out under the joist - say 75mm by 10mm - just enough
to expose the full width of the joist and a small gap either side. The
cable can then be threaded down through the gap, under, and back up the
other side, before filling the hole.


Incidentally, I do have access to an 'endoscope type' TV camera that can
be inserted into a small pilot hole to look for possible obstructions.

Should I use low-voltage LED lamps or 240 volt ones - does anyone have
any recommendations on lamp styles/manufacturers/shades of white/beam
angles etc. ?

If going halogen then definitely 12V. For LED, whatever works out most
cost effective.

Any constructive suggestions from members of this NG will be most
gratefully received.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 03/04/2014 18:46, ARW wrote:
"fred" wrote in message ...
In article , Dave Chapman
writes


Is there a 'trick-of-the-trade' or some clever (flexible ? ) device
that can be inserted through a recessed light mounting hole and allow me
to drill holes through the joists on either side for the new wiring?
Incidentally, I do have access to an 'endoscope type' TV camera that can
be inserted into a small pilot hole to look for possible obstructions.

Should I use low-voltage LED lamps or 240 volt ones - does anyone have
any recommendations on lamp styles/manufacturers/shades of white/beam
angles etc. ?


Not quite as scary as you might think.

Best to map out the approximate positions of your joists with a stud
finder and choose provisional positions for you downlighters.

Start cutting your holes and check with some probes (cable fishing
rods or some fence wire) that there are no obstructions and that your
chosen positions will work.

Working from your downlighter holes, probe to find the exact positions
of your joists and mark the surface. Then cut a slot in the PB or
lath/plaster just wide enough for 1.5mm2 T&E and just long enough to
bridge the joist.

Simply fish your cable through the joist bridges instead of drilling
joists. Then simply fill and finish, the T&E will be a few mm under
the surface.

Alternatively, you could cut a small notch in the bottom of the now
visible joist just big enough to accept the cable leaving a hole that
a bit of PB could be used to flush patch but I wouldn't bother as the
hole described above should be small enough for an easy fill with
polyfila.

Have done this invisibly a number of times on ornate corniced ceilings.


You do know that neither method is allowed by the regs don't you? If the
OP wishes to meet the regs then you would need the cable to be more than
50mm from the bottom of the joists or use one of the approved cables
with an earthed metallic covering

While not a perfect solution, something like:

http://www.tlc-direct.co.uk/Main_Ind...ion/index.html

can make a poor situation better.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 03/04/2014 20:36, ARW wrote:

The regs for cables passing through joists are very similar to cables in
walls but have no safe zone. It's reg 522.6.5 that I shall copy and
paste:-)

From the 16th edition version:

522-06-05 A cable installed under a floor or above a ceiling shall be
run in such a position that it is not liable to be damaged by contact
with the floor or the ceiling or their fixings. A cable passing through
a timber joist within a floor or ceiling construction or through a
ceiling support (e.g. under floorboards), shall:

(i) be at least 50 mm measured vertically from the top, or bottom as
appropriate, of thejoist or batten, or

(ii) incorporate an earthed armour or metal sheath suitable for use as a
protective conductor, or shall be of insulated concentric construction,
or shall be protected by enclosure in earthed steel conduit securely
supported, or by equivalent mechanical protection sufficient to prevent
penetration of the cable by nails, screws and the like (see also
Regulation 471 -13-04(v)).



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 03/04/2014 23:32, Tim Watts wrote:
On 03/04/14 23:18, Tricky Dicky wrote:
The wiki does give details of how joists should be crossed, it's in
the electrical installation section. A possible solution is also
suggested, namely notching with the notch protected with a 3mm thick
covering plate.

Richard


I'm a little curious about the whole ceilings thing. I'm not going to
argue with Adam as he's a fine man who knows his area.

But - what about all those installations where lighting wiring is pulled
though end to end and left sitting on the top of the plasterboard
(because there's not enough access to clip it to the side of the
joists), ie 12mm give or take from the surface of the ceiling. It's
quite common...

Its much harder to nail into something that is just resting on the top
of the PB (it just moves) than it is to nail into a wire that is through
a joist but too close to the surface. The latter case especially since
you would probably be aiming to hit the joist.

Note that in the Reg Adam mentioned, there is a get out clause at the
end: "or by equivalent mechanical protection sufficient to prevent
penetration of the cable by nails" that basically means if you can
protect it mechanically, then closer than 50mm from the surface is OK.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 04/04/14 04:18, John Rumm wrote:

Note that in the Reg Adam mentioned, there is a get out clause at the
end: "or by equivalent mechanical protection sufficient to prevent
penetration of the cable by nails" that basically means if you can
protect it mechanically, then closer than 50mm from the surface is OK.

Ah - I see. It really IS just the joist then, not being 50mm from the
PB surface. Been trying to get my head around the thinking behind that
one. Originally I thought the "50mm" was more to do with not weakening
the joist.

My dormers are awkward:

100mm rafters
50mm celotex between
later to get 50mm celotex below, then PB.

The only sane way to get conduit in is perpendicular to the rafters,
then smooth bend down the dormer wall until it intersects with the
hipped roof - then it is in open attic.

Conduit will be fixed to rafters and celotex butted either side.

So I guess I could put flat steel plates over where the conduit crosses
the rafter, spaced off the rafter with tube-spacers/small-blocks/whatever.


Obviously the wall can be dealt with with a dummy accessory plate to
give a zone.


Hmm - that makes things much clearer... Ta.


Tim

On Friday, April 4, 2014 8:16:25 AM UTC+1, Tim Watts wrote:

Ah - I see. It really IS just the joist then, not being 50mm from the
PB surface. Been trying to get my head around the thinking behind that one.

My lack of understanding might've be along the same lines. I didn't realise the 50mm depth was specifically regarding *joists* and thought that it was being suggested to apply to the whole ceiling i.e. in between the joists also. I was scratching my head because of the amount of cabling I've seen sitting on top of the plasterboard and figured they can't all have been cowboy jobs.

It makes sense that, as has been mentioned, it is the joist region that will be attracting screws/nails and that any such fixings between them would likely just push the cable to one side.

Mathew

In article , ARW
writes
"fred" wrote in message ...
In article , Dave Chapman

Working from your downlighter holes, probe to find the exact positions of
your joists and mark the surface. Then cut a slot in the PB or
lath/plaster just wide enough for 1.5mm2 T&E and just long enough to
bridge the joist.

Simply fish your cable through the joist bridges instead of drilling
joists. Then simply fill and finish, the T&E will be a few mm under the
surface.

Alternatively, you could cut a small notch in the bottom of the now
visible joist just big enough to accept the cable leaving a hole that a
bit of PB could be used to flush patch but I wouldn't bother as the hole
described above should be small enough for an easy fill with polyfila.

Have done this invisibly a number of times on ornate corniced ceilings.


You do know that neither method is allowed by the regs don't you?

I do now :-).

Not saying I would give flying foobar either way though.

If the OP
wishes to meet the regs then you would need the cable to be more than 50mm
from the bottom of the joists or use one of the approved cables with an
earthed metallic covering

Does that apply to RCD protected circuits too? If so, more onerous
conditions than in a walls then? Quite funny as I suspect walls are far
more likely to be pierced for fixings than ceilings.

For a little extra work the OP could cut a hole at the joist that needs to
be passed - say a 100mm diameter hole so that there is access to either side
of the joist, use a right angled drill to put a hole through the joist at
the correct height and then screw the piece of plasterboard back into place
before making good the damage.

For me that would involve bashing through lath and plaster, breaking
through the ash deadening subfloor (getting showered in ash in the
process) and then drilling through. No marks for guessing which way I'll
be doing it but at least I wont be running on diagonals across the
ceiling.

--
fred
it's a ba-na-na . . . .

On 04/04/2014 16:28, fred wrote:
In article , ARW
writes
"fred" wrote in message ...
In article , Dave Chapman

Working from your downlighter holes, probe to find the exact
positions of
your joists and mark the surface. Then cut a slot in the PB or
lath/plaster just wide enough for 1.5mm2 T&E and just long enough to
bridge the joist.

Simply fish your cable through the joist bridges instead of drilling
joists. Then simply fill and finish, the T&E will be a few mm under the
surface.

Alternatively, you could cut a small notch in the bottom of the now
visible joist just big enough to accept the cable leaving a hole that a
bit of PB could be used to flush patch but I wouldn't bother as the hole
described above should be small enough for an easy fill with polyfila.

Have done this invisibly a number of times on ornate corniced ceilings.


You do know that neither method is allowed by the regs don't you?

I do now :-).

Not saying I would give flying foobar either way though.

If the OP
wishes to meet the regs then you would need the cable to be more than
50mm
from the bottom of the joists or use one of the approved cables with an
earthed metallic covering

Does that apply to RCD protected circuits too? If so, more onerous
conditions than in a walls then? Quite funny as I suspect walls are far
more likely to be pierced for fixings than ceilings.

Now this is a slightly odd one... it would appear the short answer is Yes.

reg 522.6.6 basically restates the clauses of 522.6.5 but for cables in
walls, and then adds on the the extra permitted "safe zones" (i.e. at
wall corners, and ceiling intersection etc).

The bit about RCD protection is then in 522.6.7, that basically says if
you are not compliant with 522.6.6, then you need additional protection
from an RCD as specced in 415.1.1

However I can't see any equivalent section referring back to 522.6.5

(there is also 522.6.8 that applies to walls with metallic components -
that basically says treat it as if the cable is less than 50mm depth
regardless of how deep it actually is)




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 04/04/14 17:40, John Rumm wrote:

(there is also 522.6.8 that applies to walls with metallic components -
that basically says treat it as if the cable is less than 50mm depth
regardless of how deep it actually is)

Such as external stud walls full of foil faced celotex?

Or do they mean structural metalwork, like girders and metal studwork?

On Thursday, April 3, 2014 10:12:40 AM UTC+1, Dave Chapman wrote:
Morning all!



I'm hoping to replace a central light fitting in our kitchen by a

cluster of nine recessed LED ceiling lights and am looking for some

guidance on the best way forward.



The floor in the room above the kitchen is covered in solid laminate

so there's no easy way to lift any part of it for access to the joists

and wiring below.



I was planning to remove the existing centra light fitting and use its

mounting position and wiring to install the centre-most of the nine new

LED lights.



Running cabling ALONG between the joists around that centre light to

two more lights should be easy, but I'm wondering how I can drill the

necessary holes to run wiring sideways THROUGH the two pairs of adjacent

joists to feed the other two sets of three lights. Is it absolutely

essential to be able to lift the floor above, or cut into the kitchen

ceiling, in order to run the wiring?



Is there a 'trick-of-the-trade' or some clever (flexible ? ) device

that can be inserted through a recessed light mounting hole and allow me

to drill holes through the joists on either side for the new wiring?

Incidentally, I do have access to an 'endoscope type' TV camera that can

be inserted into a small pilot hole to look for possible obstructions.



Should I use low-voltage LED lamps or 240 volt ones - does anyone have

any recommendations on lamp styles/manufacturers/shades of white/beam

angles etc. ?



Any constructive suggestions from members of this NG will be most

gratefully received.



ATB - Dave.

It's interesting that most of this discussion has addressed the wiring problems, which are probably the greater as the question of mains versus 12v is spurious if you can't get the wires in! Only one contributor made comment on the supply and he I disagree with.

From an electronics engineer's point of view, the compressing of electronic components into the lamp base to drop 240vac to 12v or less at around 0.5A is an anethema (thought this was the right word and I see it is a "thing of abhorrence") - this suits well what I want to say. The same applied to the CFL's we all loved and cherished so dearly and like mains LED's, it wasn't the light element that failed but the insy-winsy bits crammed into the base to make them go.

Proper mains to 12v transformers in a reasonable package size cost no more and often less than an LED bulb. and will have a far greater life than any 'on-board' voltage dropper system.

I recently re-lit my hall using 20W equivalent (3W @ 12v actual) COB type - that's Chip On Board - MR16 bulbs, and the household has been impressed by the light, the spread and the total lack of waste heat. Four of these in double adjustable holders has given us far better illumination than the previous two 50W halogens.

Rob

On 04/04/2014 18:22, Tim Watts wrote:
On 04/04/14 17:40, John Rumm wrote:

(there is also 522.6.8 that applies to walls with metallic components -
that basically says treat it as if the cable is less than 50mm depth
regardless of how deep it actually is)

Such as external stud walls full of foil faced celotex?

Or do they mean structural metalwork, like girders and metal studwork?

The later I believe...


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
o.uk...
On 04/04/2014 18:22, Tim Watts wrote:
On 04/04/14 17:40, John Rumm wrote:

(there is also 522.6.8 that applies to walls with metallic components -
that basically says treat it as if the cable is less than 50mm depth
regardless of how deep it actually is)

Such as external stud walls full of foil faced celotex?

Or do they mean structural metalwork, like girders and metal studwork?

The later I believe...


There might be a reason for that

http://www.dailymail.co.uk/news/arti...QUALIFIED.html

http://www.theiet.org/forums/forum/m...threadid=57216


--
Adam

"fred" wrote in message ...
In article , ARW
writes
"fred" wrote in message ...
In article , Dave Chapman

Working from your downlighter holes, probe to find the exact positions
of
your joists and mark the surface. Then cut a slot in the PB or
lath/plaster just wide enough for 1.5mm2 T&E and just long enough to
bridge the joist.

Simply fish your cable through the joist bridges instead of drilling
joists. Then simply fill and finish, the T&E will be a few mm under the
surface.

Alternatively, you could cut a small notch in the bottom of the now
visible joist just big enough to accept the cable leaving a hole that a
bit of PB could be used to flush patch but I wouldn't bother as the hole
described above should be small enough for an easy fill with polyfila.

Have done this invisibly a number of times on ornate corniced ceilings.


You do know that neither method is allowed by the regs don't you?

I do now :-).

Not saying I would give flying foobar either way though.

If the OP
wishes to meet the regs then you would need the cable to be more than 50mm
from the bottom of the joists or use one of the approved cables with an
earthed metallic covering

Does that apply to RCD protected circuits too? If so, more onerous
conditions than in a walls then? Quite funny as I suspect walls are far
more likely to be pierced for fixings than ceilings.

For a little extra work the OP could cut a hole at the joist that needs to
be passed - say a 100mm diameter hole so that there is access to either
side
of the joist, use a right angled drill to put a hole through the joist at
the correct height and then screw the piece of plasterboard back into
place
before making good the damage.

For me that would involve bashing through lath and plaster, breaking
through the ash deadening subfloor (getting showered in ash in the
process) and then drilling through. No marks for guessing which way I'll
be doing it but at least I wont be running on diagonals across the
ceiling.

Bloody northerners and there funny ceilings:-)



--
Adam

"Tim Watts" wrote in message
...
On 03/04/14 23:18, Tricky Dicky wrote:
The wiki does give details of how joists should be crossed, it's in
the electrical installation section. A possible solution is also
suggested, namely notching with the notch protected with a 3mm thick
covering plate.

Richard


I'm a little curious about the whole ceilings thing. I'm not going to
argue with Adam as he's a fine man who knows his area.

But - what about all those installations where lighting wiring is pulled
though end to end and left sitting on the top of the plasterboard (because
there's not enough access to clip it to the side of the joists), ie 12mm
give or take from the surface of the ceiling. It's quite common...


Installation methods 100,101 and 102 all show the cable laying on the
plasterboard.

--
Adam

On 05/04/14 07:13, ARW wrote:
"John Rumm" wrote in message
o.uk...
On 04/04/2014 18:22, Tim Watts wrote:
On 04/04/14 17:40, John Rumm wrote:

(there is also 522.6.8 that applies to walls with metallic components -
that basically says treat it as if the cable is less than 50mm depth
regardless of how deep it actually is)

Such as external stud walls full of foil faced celotex?

Or do they mean structural metalwork, like girders and metal studwork?

The later I believe...


There might be a reason for that

http://www.dailymail.co.uk/news/arti...QUALIFIED.html


http://www.theiet.org/forums/forum/m...threadid=57216



Hadn't come across that! What a bizarre and unfortunate combination of
faults.

Many thanks to all those who responded to my posting and for the
interesting and useful comments made.

ATB - Dave

Hello - me again!

I'm planning to install 9 low-voltage (12v) fire-resistant LED
downlights in our kitchen ceiling and have noted with interest all of
the comments so far made to my original posting.

I'm now wondering if there's any good reason why I can't use just one
suitably rated 240v - 12v transformer mounted above the old centre-light
position, supplying all 9 of the LED downlights using low-voltage cabling.

This low-voltage approach would obviate the possible problems
associated with running AC mains cabling through the joists to feed the
downlights with 240 v, and the installation of the wiring could then be
done much more safely using the 'cut slots in plasterboard, run wiring,
and replaster over' technique.

Any thoughts/comments on this alternative approach?

TIA - Dave.

On 08/04/14 17:26, Dave Chapman wrote:
Hello - me again!

I'm planning to install 9 low-voltage (12v) fire-resistant LED
downlights in our kitchen ceiling and have noted with interest all of
the comments so far made to my original posting.

I'm now wondering if there's any good reason why I can't use just one
suitably rated 240v - 12v transformer mounted above the old centre-light
position, supplying all 9 of the LED downlights using low-voltage cabling.

This low-voltage approach would obviate the possible problems
associated with running AC mains cabling through the joists to feed the
downlights with 240 v, and the installation of the wiring could then be
done much more safely using the 'cut slots in plasterboard, run wiring,
and replaster over' technique.

Any thoughts/comments on this alternative approach?

TIA - Dave.



It might be SELV (extra low voltage) but don't overlook the fire risk
that still exists.

"Dave Chapman" wrote in message
...
Hello - me again!

I'm planning to install 9 low-voltage (12v) fire-resistant LED
downlights in our kitchen ceiling and have noted with interest all of the
comments so far made to my original posting.

I'm now wondering if there's any good reason why I can't use just one
suitably rated 240v - 12v transformer mounted above the old centre-light
position, supplying all 9 of the LED downlights using low-voltage cabling.

This low-voltage approach would obviate the possible problems associated
with running AC mains cabling through the joists to feed the downlights
with 240 v, and the installation of the wiring could then be done much
more safely using the 'cut slots in plasterboard, run wiring, and
replaster over' technique.

Any thoughts/comments on this alternative approach?


My honest opinion is - Go for it.

Make sure the transformer is replaceable -ie it fits through a spotlight
hole.

Good luck with it.

--
Adam