Hi all,

Am going to replace and move CU. will be using longer meter tails (with
a suitable switchfuse)

Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom. joist
depth is 185mm so I can run the meter tails through the existing holes.

the route is up the wall, through the ceiling - floor void then through
a wall and the down to the new CU location.

In article ,
Stephen H writes:

Hi all,

Am going to replace and move CU. will be using longer meter tails (with
a suitable switchfuse)

Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom. joist
depth is 185mm so I can run the meter tails through the existing holes.

the route is up the wall, through the ceiling - floor void then through
a wall and the down to the new CU location.

Sounds OK, as long as they are always 50mm behind any surface, or are
surface mounted.

If I was looking to do this, I would probably use SWA (indeed, this
is what I've seen used where this has been done) or concentric supply
cable which is easier to handle for the same CSA:
http://www.diynot.com/wiki/electrics...lit_concentric

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Stephen H wrote:


Hi all,

Am going to replace and move CU. will be using longer meter tails (with
a suitable switchfuse)

Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom. joist
depth is 185mm so I can run the meter tails through the existing holes.

the route is up the wall, through the ceiling - floor void then through
a wall and the down to the new CU location.

I do not *think* that contravenes any specific regulation.

What you need to do is consider damage potential. If the holes in the joists
are half way between top and bottom and so (presumably) 50mm from either
floor or ceiling surface, then it is highly unlikely anyone could bang a
nail through the cables from either direction.

Which all sounds OK if I undertsnad you correctly.

If the cables are surface mounted on the walls at both entry and exit, there
is no problem there either.

--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"She got her looks from her father. He's a plastic surgeon."

In article ,
(Andrew Gabriel) writes:
If I was looking to do this, I would probably use SWA (indeed, this
is what I've seen used where this has been done) or concentric supply
cable which is easier to handle for the same CSA:
http://www.diynot.com/wiki/electrics...lit_concentric

But don't do what they've done in the second picture down that page!

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
In article ,
(Andrew Gabriel) writes:
If I was looking to do this, I would probably use SWA (indeed, this
is what I've seen used where this has been done) or concentric
supply cable which is easier to handle for the same CSA:
http://www.diynot.com/wiki/electrics...lit_concentric

But don't do what they've done in the second picture down that page!

Andrew - We have our own pictures of such things. There is no need to link
to a lesser site:-)

http://wiki.diyfaq.org.uk/index.php?...Earthing_Types

--
Adam

In article ,
"ARW" writes:
Andrew Gabriel wrote:
In article ,
(Andrew Gabriel) writes:
If I was looking to do this, I would probably use SWA (indeed, this
is what I've seen used where this has been done) or concentric
supply cable which is easier to handle for the same CSA:
http://www.diynot.com/wiki/electrics...lit_concentric

But don't do what they've done in the second picture down that page!

Andrew - We have our own pictures of such things. There is no need to link
to a lesser site:-)

http://wiki.diyfaq.org.uk/index.php?...Earthing_Types

I pointed at that page for the details of how to make off concentric
wiring. I couldn't find any details/pictures of this on our diyfaq.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
In article ,
"ARW" writes:
Andrew Gabriel wrote:
In article ,
(Andrew Gabriel) writes:
If I was looking to do this, I would probably use SWA (indeed,
this is what I've seen used where this has been done) or
concentric supply cable which is easier to handle for the same
CSA:
http://www.diynot.com/wiki/electrics...lit_concentric

But don't do what they've done in the second picture down that
page!

Andrew - We have our own pictures of such things. There is no need
to link to a lesser site:-)

http://wiki.diyfaq.org.uk/index.php?...Earthing_Types

I pointed at that page for the details of how to make off concentric
wiring. I couldn't find any details/pictures of this on our diyfaq.

Well that will give me something to do in the new year:-)



--
Adam

Stephen H wrote:
Hi all,

Am going to replace and move CU. will be using longer meter tails
(with a suitable switchfuse)

Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom.
joist depth is 185mm so I can run the meter tails through the
existing holes.
the route is up the wall, through the ceiling - floor void then
through a wall and the down to the new CU location.

As Andrew says 50mm from the surface is fine.

Your new CU now seems to be going into a different position to the one it
was going to be in. Is a certain female changing her mind about where you
are allowed to put your new CU? If so then decide where you want it and say
to her whilst pointing at the said spot "the CU cannot go there". Job done.

--
Adam

Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom.
joist depth is 185mm so I can run the meter tails through the
existing holes.

the route is up the wall, through the ceiling - floor void then
through a wall and the down to the new CU location.

I do not *think* that contravenes any specific regulation.

What you need to do is consider damage potential. If the holes in the
joists are half way between top and bottom and so (presumably) 50mm
from either floor or ceiling surface, then it is highly unlikely
anyone could bang a nail through the cables from either direction.

Which all sounds OK if I undertsnad you correctly.

If the cables are surface mounted on the walls at both entry and
exit, there is no problem there either.

Pedantic question: would those carrying out building control checks and
EICRs ignore as de minimis any bits where the bends in the meter tails
mean they are out of sight but less than 50mm from the surface of the
ceiling? I have in mind that 25mm tails have a minimum bend radius of
roughly 70mm. So - unless a few inches of the ceiling are cut out
either side to expose the S-bend - there must be a bit just after they
go into the ceiling and just after where they come out which technically
doesn't comply. And IIRC the provision in the regs for a 150mm "safe
zone" only applies to cables in walls, not cables in ceilings.

Of course I hope for the OP's sake the answer is that even a bolshie
inspector would not quibble.

--
Robin
reply to address is (meant to be) valid

In article ,
Robin wrote:
Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom.
joist depth is 185mm so I can run the meter tails through the
existing holes.

the route is up the wall, through the ceiling - floor void then
through a wall and the down to the new CU location.

I do not *think* that contravenes any specific regulation.

What you need to do is consider damage potential. If the holes in the
joists are half way between top and bottom and so (presumably) 50mm
from either floor or ceiling surface, then it is highly unlikely
anyone could bang a nail through the cables from either direction.

Which all sounds OK if I undertsnad you correctly.

If the cables are surface mounted on the walls at both entry and
exit, there is no problem there either.

Pedantic question: would those carrying out building control checks and
EICRs ignore as de minimis any bits where the bends in the meter tails
mean they are out of sight but less than 50mm from the surface of the
ceiling? I have in mind that 25mm tails have a minimum bend radius of
roughly 70mm.

As installed when a new meter was fitted, bend diameter 60mm.

--
From KT24

Using a RISC OS computer running v5.18

Robin wrote:

Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom.
joist depth is 185mm so I can run the meter tails through the
existing holes.

the route is up the wall, through the ceiling - floor void then
through a wall and the down to the new CU location.

I do not *think* that contravenes any specific regulation.

What you need to do is consider damage potential. If the holes in the
joists are half way between top and bottom and so (presumably) 50mm
from either floor or ceiling surface, then it is highly unlikely
anyone could bang a nail through the cables from either direction.

Which all sounds OK if I undertsnad you correctly.

If the cables are surface mounted on the walls at both entry and
exit, there is no problem there either.

Pedantic question: would those carrying out building control checks and
EICRs ignore as de minimis any bits where the bends in the meter tails
mean they are out of sight but less than 50mm from the surface of the
ceiling? I have in mind that 25mm tails have a minimum bend radius of
roughly 70mm. So - unless a few inches of the ceiling are cut out
either side to expose the S-bend - there must be a bit just after they
go into the ceiling and just after where they come out which technically
doesn't comply. And IIRC the provision in the regs for a 150mm "safe
zone" only applies to cables in walls, not cables in ceilings.

Of course I hope for the OP's sake the answer is that even a bolshie
inspector would not quibble.


The "50mm wall rule" is regulation 522.6.6 which does not apply to ceilings
- only "walls and partitions".

Regulation 522.6.5 applies to cables in ceilings and in summary says:

50mm above ceiling and below floor (above) *when passing through a joist or
support* only.

Cables may lie on the ceiling in other locations and often do.

If the joist is a problem, clause (v) of the same regulation says you may
mechanically protect it against nails and screws - (eg with steel plate).

As you are not likely to use an SDS on a ceiling, 3mm or so plate should be
enough.




--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"A fanatic is one who can't change his mind and won't change the subject."

Robin wrote:
Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom.
joist depth is 185mm so I can run the meter tails through the
existing holes.

the route is up the wall, through the ceiling - floor void then
through a wall and the down to the new CU location.

I do not *think* that contravenes any specific regulation.

What you need to do is consider damage potential. If the holes in
the joists are half way between top and bottom and so (presumably)
50mm from either floor or ceiling surface, then it is highly
unlikely anyone could bang a nail through the cables from either
direction. Which all sounds OK if I undertsnad you correctly.

If the cables are surface mounted on the walls at both entry and
exit, there is no problem there either.

Pedantic question: would those carrying out building control checks
and EICRs ignore as de minimis any bits where the bends in the meter
tails mean they are out of sight but less than 50mm from the surface
of the ceiling? I have in mind that 25mm tails have a minimum bend
radius of roughly 70mm. So - unless a few inches of the ceiling are
cut out either side to expose the S-bend - there must be a bit just
after they go into the ceiling and just after where they come out
which technically doesn't comply.



And IIRC the provision in the regs
for a 150mm "safe zone" only applies to cables in walls, not cables
in ceilings.

The regs say "within 150mm of the top of a wall":-) And they are about as
comprehensive as a Star Trek captains directional coordinates.


Of course I hope for the OP's sake the answer is that even a bolshie
inspector would not quibble.

Out of Sight, Out of Mind

http://www.youtube.com/watch?v=pI2UN...eature=related


--
Adam

And IIRC the provision in the regs
for a 150mm "safe zone" only applies to cables in walls, not cables
in ceilings.

The regs say "within 150mm of the top of a wall":-) And they are
about as comprehensive as a Star Trek captains directional
coordinates.

I only have access here to the draft regs and in those 522.6.6 reads "A
cable concealed in a wall or partition at a depth of less than 50 mm
from the surfaces of the wall or partition shall: ... (iii) be installed
in a zone within 150 mm from the top of the wall or partition or within
150 mm of an angle formed by two adjoining walls or partitions." I took
the opening words to mean 522.6.6 does not aply at all to cables in a
ceiling (or floor). I thought that's also why 522.6.6 and 7 were
separeate and distinct from 522.6.5 which does deal with ceilings and
floors. But looking at that again in the light of Tim Watts' comments I
can see it might be a way out.
--
Robin
reply to address is (meant to be) valid

The "50mm wall rule" is regulation 522.6.6 which does not apply to
ceilings - only "walls and partitions".

Regulation 522.6.5 applies to cables in ceilings and in summary says:

50mm above ceiling and below floor (above) *when passing through a
joist or support* only.

That is the 50mm rule I had in mind.

Cables may lie on the ceiling in other locations and often do.

Yes indeed, but I had thought that under the 17th edition such cables
routinely needed RCD protection. Looking at (the draft) text in the
light of your comments I see though that it does indeed only require a
50mm gap from the top and bottom of a joist or batten it passes through.
Seems a bit bizarre to me given how tight they have made the regs for
walls but I guess they have risk-assessed it on th basis that far fewer
people fix thinsg to ceilings/floors than to walls. So thanks for
educating me - and for providing at least a small example of where some
small risk was accepted.

--
Robin
reply to address is (meant to be) valid

On 31/12/2012 12:42, ARW wrote:
Stephen H wrote:
Hi all,

Am going to replace and move CU. will be using longer meter tails
(with a suitable switchfuse)

Now is it acceptable to route meter tails between the ground floor
ceiling and the first floor floorboards?

There are already holes in joists halfway between top and bottom.
joist depth is 185mm so I can run the meter tails through the
existing holes.
the route is up the wall, through the ceiling - floor void then
through a wall and the down to the new CU location.

As Andrew says 50mm from the surface is fine.

Your new CU now seems to be going into a different position to the one it
was going to be in. Is a certain female changing her mind about where you
are allowed to put your new CU? If so then decide where you want it and say
to her whilst pointing at the said spot "the CU cannot go there". Job done.


not really, its just I'm optimising the meter tails route from meter
cupboard to new CU location before buying materials and actually doing
the job.

Basically route one was through wall from meter cupboard into d/stairs
family room

travel up almost to ceiling, turn left travel for 2 metres then hole
through wall above door way into hall way and then into CU in hall way.

Main issue with this route 1 is that the meter tails have to then cross
the room light switch cable which is by door.

2nd route is similar but actually go up into ceiling-floor void, through
the joists, then drop back down to above door and then through to CU.
Main advantage is less 3mm plate steel needed.

Hence my question.

Pedantic question: would those carrying out building control checks
and EICRs ignore as de minimis any bits where the bends in the meter
tails mean they are out of sight but less than 50mm from the surface
of the ceiling? I have in mind that 25mm tails have a minimum bend
radius of roughly 70mm.

As installed when a new meter was fitted, bend diameter 60mm.

Do you happen to know what cable that is pl? In the light of what you
have I've checked the manfr's specs for the tails he they state a
minimum bend radius of 4 x the diameter (as in the OSG) and a diameter
of 11.2 giving a minimum radius of 45mm. That's a good deal less than
the 70mm I thought but still adds up to a diameter of nearly 90mm.
Something more flexible would be worth knowing about "just in case".

--
--
Robin
reply to address is (meant to be) valid

In article ,
Robin wrote:
Pedantic question: would those carrying out building control checks
and EICRs ignore as de minimis any bits where the bends in the meter
tails mean they are out of sight but less than 50mm from the surface
of the ceiling? I have in mind that 25mm tails have a minimum bend
radius of roughly 70mm.

As installed when a new meter was fitted, bend diameter 60mm.

Do you happen to know what cable that is pl? In the light of what you
have I've checked the manfr's specs for the tails he they state a
minimum bend radius of 4 x the diameter (as in the OSG) and a diameter
of 11.2 giving a minimum radius of 45mm. That's a good deal less than
the 70mm I thought but still adds up to a diameter of nearly 90mm.
Something more flexible would be worth knowing about "just in case".

--
The OD (sheath) is 10mm, but I've no tables to turn that into cable size.
And I've no idea of the size of the "Company fuse", the meter has a max
rating of 100A.

--
From KT24

Using a RISC OS computer running v5.18

The OD (sheath) is 10mm, but I've no tables to turn that into cable
size. And I've no idea of the size of the "Company fuse", the meter
has a max rating of 100A.

Thanks for looking/measuring.
--
Robin
reply to address is (meant to be) valid