For my cloakroom project, I am pondering on a few electrical and other
questions:

At present there is a central ceiling rose which has a lighting circuit
looping through it. In the conventional way, a pull cord switch is
connected to this and there is a separate feed of permanent and
switched phase, neutral and earth going to the ventilation fan.

To provide a little detail, the room is rectangular with the door at
one end of the long side. The ceiling joists run parallel to the long
dimension. The ventilation fan is towards one end of the room and
central and has a duct to deliver the exhaust air a few metres to the
edge of the house.

There is not easy access from above, so work will have to be done from
below. I would prefer to minimise repair work on the ceiling
plasterboard.

At one end of the room, further from the door, the throne will be
installed with concealed cistern covered with small granite shelf.
Above this, with a space for whatever, will be a wall cupboard which
will go to a height of about 200mm below the ceiling.

The intention is to do away with the ceiling rose and pull switch and
re-route the wiring to run on the walls. There will be a plate switch
inside the door, from which cable will run horizontally to the corner.
From there it will run vertically in the 150mm allowed space, behind
the cupboard, to the space above it.

Ideally, I would like to run a new cable from the existing ceiling rose
position, across the ceiling, above the plasterboard, drop it down
above the cupboard and make connections there.

This raises two questions:

1) In effect, this creates a spur - i.e. the daisy chain of the
lighting circuit comes to the ceiling rose position and the cable to
feed the lighting circuit to the edge of the room above the cupboard
would be teed from it. I suppose that I could run two cables and
effectively maintain the daisy chain. I can't find any rules on this
in BS7671 one way or the other.

2) I need a solution for jointing the cables at the ceiling rose
position. Crimps are the obvious choice since the hole will be
repaired and covered. However, I could do with a solution to provide
the second required level of insulation etc. Conventional junction
boxes don't seem very suitable because of the screw terminals, although
I suppose those could be removed; but also I don't really want to make
the ceiling hole larger if I can help it. Is heat shrink tube
permissible in this application to provide the second layer of
insulation? Any other ideas?


Ventilation:

3) I want to move the fan from its current ceiling mount position to
being fitted above the cupboard. There would then be a removable
grille above the cupboard. The idea is to make the ceiling clear, and
I should be able to reduce the noise of the already quiet Vent Axia fan
even further. I can't find any Building Regulations objection to so
doing. Anybody know different?

4) I believe the Buiding Regulations specify that the fan comes on when
the light is switched on and should run for a period of time after it
has been switched off. However, I am intending to have two sets of
lights; one being under-cupboard and the other some downlighters on the
long wall or wall lights. So the question arises of whether the fan
should come on when the "main" light is switched on or when either is
switched on. Obviously I could do the latter with relays.

Comments?

Andy Hall wrote:

This raises two questions:

1) In effect, this creates a spur - i.e. the daisy chain of the lighting
circuit comes to the ceiling rose position and the cable to feed the
lighting circuit to the edge of the room above the cupboard would be
teed from it. I suppose that I could run two cables and effectively
maintain the daisy chain. I can't find any rules on this in BS7671 one
way or the other.

Since the lighting circuit is a radial there is no actual requirement
for it to follow a linear progression from one light to the next. You
can split it any which way you find convenient - taking "spurs" or
adding branches when you need.

2) I need a solution for jointing the cables at the ceiling rose
position. Crimps are the obvious choice since the hole will be
repaired and covered. However, I could do with a solution to provide
the second required level of insulation etc. Conventional junction
boxes don't seem very suitable because of the screw terminals, although
I suppose those could be removed; but also I don't really want to make
the ceiling hole larger if I can help it. Is heat shrink tube
permissible in this application to provide the second layer of
insulation? Any other ideas?

IIUC heat shrink is acceptable in this case (it would be acceptable for
jointing a cable that you then buried in plaster, so entombing it in the
ceiling void should not be a problem).

Ventilation:

3) I want to move the fan from its current ceiling mount position to
being fitted above the cupboard. There would then be a removable
grille above the cupboard. The idea is to make the ceiling clear, and I
should be able to reduce the noise of the already quiet Vent Axia fan
even further. I can't find any Building Regulations objection to so
doing. Anybody know different?

Can't think of any reason why not.

4) I believe the Buiding Regulations specify that the fan comes on when
the light is switched on and should run for a period of time after it
has been switched off. However, I am intending to have two sets of
lights; one being under-cupboard and the other some downlighters on the
long wall or wall lights. So the question arises of whether the fan
should come on when the "main" light is switched on or when either is
switched on. Obviously I could do the latter with relays.

Comments?

I would go with the "main" light only. The also gives you an easy option
for circumventing the starting of the fan on any occasion that you wish
to so do. (which building reg were you thinking about BTW?)

--
Cheers,

John.

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

On 2006-08-12 02:42:54 +0100, John Rumm said:

Andy Hall wrote:

This raises two questions:

1) In effect, this creates a spur - i.e. the daisy chain of the
lighting circuit comes to the ceiling rose position and the cable to
feed the lighting circuit to the edge of the room above the cupboard
would be teed from it. I suppose that I could run two cables and
effectively maintain the daisy chain. I can't find any rules on this
in BS7671 one way or the other.

Since the lighting circuit is a radial there is no actual requirement
for it to follow a linear progression from one light to the next. You
can split it any which way you find convenient - taking "spurs" or
adding branches when you need.

That was my thought as well. I couldn't think of any reason to
follow a particular pattern - the lighting circuits are protected by 6A
MCB. However, the information about radial circuits is written in
terms of power circuits.




2) I need a solution for jointing the cables at the ceiling rose
position. Crimps are the obvious choice since the hole will be
repaired and covered. However, I could do with a solution to provide
the second required level of insulation etc. Conventional junction
boxes don't seem very suitable because of the screw terminals, although
I suppose those could be removed; but also I don't really want to make
the ceiling hole larger if I can help it. Is heat shrink tube
permissible in this application to provide the second layer of
insulation? Any other ideas?

IIUC heat shrink is acceptable in this case (it would be acceptable for
jointing a cable that you then buried in plaster, so entombing it in
the ceiling void should not be a problem).

Initially I was concerned about lack of mechanical support as well, but
realised that this isn't provided in screw terminal junction boxes
anyway.



Ventilation:

3) I want to move the fan from its current ceiling mount position to
being fitted above the cupboard. There would then be a removable
grille above the cupboard. The idea is to make the ceiling clear, and
I should be able to reduce the noise of the already quiet Vent Axia fan
even further. I can't find any Building Regulations objection to so
doing. Anybody know different?

Can't think of any reason why not.

4) I believe the Buiding Regulations specify that the fan comes on when
the light is switched on and should run for a period of time after it
has been switched off. However, I am intending to have two sets of
lights; one being under-cupboard and the other some downlighters on the
long wall or wall lights. So the question arises of whether the fan
should come on when the "main" light is switched on or when either is
switched on. Obviously I could do the latter with relays.

Comments?

I would go with the "main" light only. The also gives you an easy
option for circumventing the starting of the fan on any occasion that
you wish to so do. (which building reg were you thinking about BTW?)

There's some rather waffly stuff on this in the Approved Doc. to Part
F. Looking again, I just found a relevant comment that the fan "could
be controlled" by the main light switch. Good enough. The one for
the downlighters will do.

Andy Hall wrote:

Initially I was concerned about lack of mechanical support as well, but
realised that this isn't provided in screw terminal junction boxes anyway.

That's why junction boxes should always be screwed to something and the
cables clipped or otherwise secured near the entry points. It this case
if you use adhesive-lined heatshrink for the outer sleeving you should
be able to make a secure joint.

--
Andy

On 2006-08-12 09:53:02 +0100, Andy Wade said:

Andy Hall wrote:

Initially I was concerned about lack of mechanical support as well, but
realised that this isn't provided in screw terminal junction boxes
anyway.

That's why junction boxes should always be screwed to something and the
cables clipped or otherwise secured near the entry points. It this
case if you use adhesive-lined heatshrink for the outer sleeving you
should be able to make a secure joint.

Thanks.

Didn't realise that heatshrink was available with adhesive lining.
Presumably this is like hot melt glue....

Andy Hall wrote:

Didn't realise that heatshrink was available with adhesive lining.
Presumably this is like hot melt glue....

It's readily available - RS, Farnell etc. Sticks like **** to ...

--
Andy

On 2006-08-12 10:33:51 +0100, Andy Wade said:

Andy Hall wrote:

Didn't realise that heatshrink was available with adhesive lining.
Presumably this is like hot melt glue....

It's readily available - RS, Farnell etc. Sticks like **** to ...

Excellent.

I need to do an RS order this weekend, so it can go on that.

Andy Hall wrote:
For my cloakroom project, I am pondering on a few electrical and other
questions:

At present there is a central ceiling rose which has a lighting circuit
looping through it. In the conventional way, a pull cord switch is
connected to this and there is a separate feed of permanent and switched
phase, neutral and earth going to the ventilation fan.

To provide a little detail, the room is rectangular with the door at
one end of the long side. The ceiling joists run parallel to the long
dimension. The ventilation fan is towards one end of the room and
central and has a duct to deliver the exhaust air a few metres to the
edge of the house.

Make it far bigger than you think you need, then, and use a more
powerful fan, and if its hidden in the roof space, a really good quality
QUIET one that won't need replacing in 6 months...


There is not easy access from above, so work will have to be done from
below. I would prefer to minimise repair work on the ceiling plasterboard.

At one end of the room, further from the door, the throne will be
installed with concealed cistern covered with small granite shelf.
Above this, with a space for whatever, will be a wall cupboard which
will go to a height of about 200mm below the ceiling.

The intention is to do away with the ceiling rose and pull switch and
re-route the wiring to run on the walls. There will be a plate switch
inside the door,

Not legal unless the bathroom is very big. Outside with an isolator up
near the ceiling is conventional.

from which cable will run horizontally to the corner.
From there it will run vertically in the 150mm allowed space, behind
the cupboard, to the space above it.

Ideally, I would like to run a new cable from the existing ceiling rose
position, across the ceiling, above the plasterboard, drop it down above
the cupboard and make connections there.

This raises two questions:

1) In effect, this creates a spur - i.e. the daisy chain of the lighting
circuit comes to the ceiling rose position and the cable to feed the
lighting circuit to the edge of the room above the cupboard would be
teed from it. I suppose that I could run two cables and effectively
maintain the daisy chain. I can't find any rules on this in BS7671 one
way or the other.

All lighting is spur wired.


2) I need a solution for jointing the cables at the ceiling rose
position. Crimps are the obvious choice since the hole will be
repaired and covered. However, I could do with a solution to provide
the second required level of insulation etc. Conventional junction
boxes don't seem very suitable because of the screw terminals, although
I suppose those could be removed; but also I don't really want to make
the ceiling hole larger if I can help it. Is heat shrink tube
permissible in this application to provide the second layer of
insulation? Any other ideas?


Solder and heatshrink is allowed as is crimping. Those can be
permanently boxed in and meet regs. Unless you are an avid soldere ger
some crimps and a tool.

Ventilation:

3) I want to move the fan from its current ceiling mount position to
being fitted above the cupboard. There would then be a removable
grille above the cupboard. The idea is to make the ceiling clear, and I
should be able to reduce the noise of the already quiet Vent Axia fan
even further. I can't find any Building Regulations objection to so
doing. Anybody know different?

No, its fine. regs merely say you need a given airflow. How you achieve
it is up to you BUT fans in long tubes are very ineffective. IIRC
centrifugal fans are better than acxial.


4) I believe the Buiding Regulations specify that the fan comes on when
the light is switched on and should run for a period of time after it
has been switched off. However, I am intending to have two sets of
lights; one being under-cupboard and the other some downlighters on the
long wall or wall lights. So the question arises of whether the fan
should come on when the "main" light is switched on or when either is
switched on. Obviously I could do the latter with relays.

Best of all, use a humidity controlled fan with a manual override.


Comments?

On 2006-08-12 15:21:35 +0100, Owain said:

Andy Hall wrote:
This raises two questions:
1) In effect, this creates a spur - i.e. the daisy chain of the
lighting circuit comes to the ceiling rose position and the cable to
feed the lighting circuit to the edge of the room above the cupboard
would be teed from it.

Not a problem on a radial circuit, which lighting is.

2) I need a solution for jointing the cables at the ceiling rose
position. Crimps are the obvious choice since the hole will be
repaired and covered. However, I could do with a solution to provide
the second required level of insulation etc.

I would flush in a 2" conduit box (in fact you might already have one
behind the rose) and use a screw-on cover (as used for plastic conduit
systems). If you then paint over that it becomes "almost" invisible, yet
remains accessible

Or you could keep the ceiling rose location and use a PIR detector to
trigger the fan timer?

That's a thought if I could get a flush one. I want to avoid
projecting pieces.



Ventilation:
3) I want to move the fan from its current ceiling mount position to
being fitted above the cupboard. There would then be a removable
grille above the cupboard.

I'm not /quite/ sure about what you want. Are you talking about having

______
| |
[] V - R O O M
=====duct=====[] O -
[] I - - vent grill
| D -
|______|

where

[]
===[] is the fan blowing out the back to a duct
[]


In which case the VOID area might get rather dusty and I think I would
be inclined to go for a new duct-mounted fan mounted on
vibration-absorbing rubber mounts.

Something like that. Apart from noise reduction, I want to remove
the fan from the ceiling area. I was thinking of making a
compartmented area for the fan so that any dust is confined to it.




4) I believe the Buiding Regulations specify that the fan comes on when
the light is switched on and should run for a period of time after it
has been switched off. However, I am intending to have two sets of
lights; one being under-cupboard and the other some downlighters on the
long wall or wall lights. So the question arises of whether the fan
should come on when the "main" light is switched on or when either is
switched on. Obviously I could do the latter with relays.

I suggest not using relays - use double-pole switches, one pole on each
switch can switch the lights, the 2nd pole is paralled and switches the
fan. This may necessitate gridswitch.

Yes of course. Simple OR function. Extra cable to the switch, but
that doesn't matter.



I suggest you also put in a 13A fused power spur adjacent to the WC so
you can upgrade to one of those Japanese bottom-washing toilets at a
later date without having to disturb the tiling.

Well actually there's just the collar for the soil pipe in the floor at
the moment. I was thinking that another possibility would be to
create one of those French deals where there's just a hole in the floor
and a place either side to put each foot.




Owain

Andy Hall wrote:

On 2006-08-12 10:33:51 +0100, Andy Wade
said:

Andy Hall wrote:

Didn't realise that heatshrink was available with adhesive lining.
Presumably this is like hot melt glue....


It's readily available - RS, Farnell etc. Sticks like **** to ...


Excellent.

I need to do an RS order this weekend, so it can go on that.

You can also improvise I have found.... slice slivers off a glue stick
off with a sharp knife, and slide them into the heatshrink assembly
before heating. The whole lot should end up nicely sealed once heated.

--
Cheers,

John.

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

On 2006-08-12 18:18:03 +0100, John Rumm said:

Andy Hall wrote:

On 2006-08-12 10:33:51 +0100, Andy Wade said:

Andy Hall wrote:

Didn't realise that heatshrink was available with adhesive lining.
Presumably this is like hot melt glue....


It's readily available - RS, Farnell etc. Sticks like **** to ...


Excellent.

I need to do an RS order this weekend, so it can go on that.

You can also improvise I have found.... slice slivers off a glue stick
off with a sharp knife, and slide them into the heatshrink assembly
before heating. The whole lot should end up nicely sealed once heated.

Now that is creative. Excellent idea. Thanks.

On 2006-08-12 18:01:09 +0100, The Natural Philosopher said:

Andy Hall wrote:
For my cloakroom project, I am pondering on a few electrical and other
questions:

At present there is a central ceiling rose which has a lighting circuit
looping through it. In the conventional way, a pull cord switch is
connected to this and there is a separate feed of permanent and
switched phase, neutral and earth going to the ventilation fan.

To provide a little detail, the room is rectangular with the door at
one end of the long side. The ceiling joists run parallel to the long
dimension. The ventilation fan is towards one end of the room and
central and has a duct to deliver the exhaust air a few metres to the
edge of the house.

Make it far bigger than you think you need, then, and use a more
powerful fan, and if its hidden in the roof space, a really good
quality QUIET one that won't need replacing in 6 months...

It's a ground floor cloakroom. The duct runs in the space between
floor above and ceiling. The fan is OK - a Vent Axia - so no need to
change. There isn't any way to get access to the duct along any of
its length so hence the plan to conceal it.




There is not easy access from above, so work will have to be done from
below. I would prefer to minimise repair work on the ceiling
plasterboard.

At one end of the room, further from the door, the throne will be
installed with concealed cistern covered with small granite shelf.
Above this, with a space for whatever, will be a wall cupboard which
will go to a height of about 200mm below the ceiling.

The intention is to do away with the ceiling rose and pull switch and
re-route the wiring to run on the walls. There will be a plate switch
inside the door,

Not legal unless the bathroom is very big. Outside with an isolator up
near the ceiling is conventional.

It's a cloakroom - no bath or shower - so OK.



from which cable will run horizontally to the corner. From there it
will run vertically in the 150mm allowed space, behind the cupboard, to
the space above it.

Ideally, I would like to run a new cable from the existing ceiling rose
position, across the ceiling, above the plasterboard, drop it down
above the cupboard and make connections there.

This raises two questions:

1) In effect, this creates a spur - i.e. the daisy chain of the
lighting circuit comes to the ceiling rose position and the cable to
feed the lighting circuit to the edge of the room above the cupboard
would be teed from it. I suppose that I could run two cables and
effectively maintain the daisy chain. I can't find any rules on this
in BS7671 one way or the other.

All lighting is spur wired.


2) I need a solution for jointing the cables at the ceiling rose
position. Crimps are the obvious choice since the hole will be
repaired and covered. However, I could do with a solution to provide
the second required level of insulation etc. Conventional junction
boxes don't seem very suitable because of the screw terminals, although
I suppose those could be removed; but also I don't really want to make
the ceiling hole larger if I can help it. Is heat shrink tube
permissible in this application to provide the second layer of
insulation? Any other ideas?


Solder and heatshrink is allowed as is crimping. Those can be
permanently boxed in and meet regs. Unless you are an avid soldere ger
some crimps and a tool.

I have and can do both easily enough. I was more concerned about how
to achieve a sensible second layer of insulation and a mechanically
sound joint.




Ventilation:

3) I want to move the fan from its current ceiling mount position to
being fitted above the cupboard. There would then be a removable
grille above the cupboard. The idea is to make the ceiling clear, and
I should be able to reduce the noise of the already quiet Vent Axia fan
even further. I can't find any Building Regulations objection to so
doing. Anybody know different?

No, its fine. regs merely say you need a given airflow. How you achieve
it is up to you BUT fans in long tubes are very ineffective. IIRC
centrifugal fans are better than acxial.

They are, but a lot noiser as well.

The fan is adequate so I'm not concerned about that aspect.






4) I believe the Buiding Regulations specify that the fan comes on when
the light is switched on and should run for a period of time after it
has been switched off. However, I am intending to have two sets of
lights; one being under-cupboard and the other some downlighters on the
long wall or wall lights. So the question arises of whether the fan
should come on when the "main" light is switched on or when either is
switched on. Obviously I could do the latter with relays.

Best of all, use a humidity controlled fan with a manual override.

No shower or bath so no extra humidity...

On 2006-08-12 20:39:13 +0100, Owain said:

Andy Hall wrote:
Or you could keep the ceiling rose location and use a PIR detector to
trigger the fan timer?
That's a thought if I could get a flush one. I want to avoid
projecting pieces.

Elkay 374A
http://www.elkay.co.uk/product.asp?p...rgy_management

Hmm. that would work.





Well actually there's just the collar for the soil pipe in the floor at
the moment. I was thinking that another possibility would be to
create one of those French deals where there's just a hole in the floor
and a place either side to put each foot.

What, a S*n*f*o??? ;-)

Oh good grief no.

http://en.wikipedia.org/wiki/Squat_toilet

Take a look at the Japanese one. I imagine that the cistern is made
by Rinnai and doubles as a combi to save space. It seems to have a
flue....