Hello,


I'm starting to install some interlinked smoke and heat alarms. Can they
use L & N from different circuits, or sgould they have a seperate dedicated
one.

John M

--
John Mulrooney
NOTE Email address IS correct but might not be checked for a while.

On Sunday, 14 June 2015 13:03:03 UTC+1, John Mulrooney wrote:
I'm starting to install some interlinked smoke and heat alarms. Can they
use L & N from different circuits, or sgould they have a seperate dedicated
one.

All alarms must be on the same circuit.

It doesn't have to be a dedicated alarm-only circuit and there are good reasons for it not being so; but the alarms should then have battery or capacitor back-up.

On a mixed use circuit you are likely to notice a supply failure more quickly than if only the alarms are affected.

Owain

On Sun, 14 Jun 2015 05:20:35 -0700, spuorgelgoog wrote:

On Sunday, 14 June 2015 13:03:03 UTC+1, John Mulrooney wrote:
I'm starting to install some interlinked smoke and heat alarms. Can
they use L & N from different circuits, or sgould they have a seperate
dedicated one.

All alarms must be on the same circuit.

It doesn't have to be a dedicated alarm-only circuit and there are good
reasons for it not being so; but the alarms should then have battery or
capacitor back-up.

On a mixed use circuit you are likely to notice a supply failure more
quickly than if only the alarms are affected.

Or do what I do and put a prominent non-maintained emergency light on the
same circuit. Useful in its own right.

On 14/06/2015 13:55, Bob Eager wrote:
On Sun, 14 Jun 2015 05:20:35 -0700, spuorgelgoog wrote:

On Sunday, 14 June 2015 13:03:03 UTC+1, John Mulrooney wrote:
I'm starting to install some interlinked smoke and heat alarms. Can
they use L & N from different circuits, or sgould they have a seperate
dedicated one.

All alarms must be on the same circuit.

It doesn't have to be a dedicated alarm-only circuit and there are good
reasons for it not being so; but the alarms should then have battery or
capacitor back-up.

On a mixed use circuit you are likely to notice a supply failure more
quickly than if only the alarms are affected.

Or do what I do and put a prominent non-maintained emergency light on the
same circuit. Useful in its own right.

Yup that was my preferred solution as well. I also fitted a centralised
switch so that the alarms can be tested or silenced from one place
easily (since some are well out of reach on 10' high ceilings)


--
Cheers,

John.

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

On 14/06/15 13:02, John Mulrooney wrote:
Hello,


I'm starting to install some interlinked smoke and heat alarms. Can they
use L & N from different circuits, or sgould they have a seperate dedicated
one.

John M


The must be on the same circuit and generally are put on a lighting
circuit (ground floor preferred) so that circuit trip is immediately
apparent (evening/night at least).

"Tim Watts" wrote in message
...

The must be on the same circuit and generally are put on a lighting
circuit (ground floor preferred) so that circuit trip is immediately
apparent (evening/night at least).


If you do that then there should be a means of isolating the smokes whilst
still leaving the lights powered up.

--
Adam

On 14/06/15 17:07, ARW wrote:
"Tim Watts" wrote in message
...

The must be on the same circuit and generally are put on a lighting
circuit (ground floor preferred) so that circuit trip is immediately
apparent (evening/night at least).


If you do that then there should be a means of isolating the smokes
whilst still leaving the lights powered up.


Is there a recommended way? I presume it should not be *too* easy?
Emergency key type test switch or just an out of the way normal isolator?

In article ,
John Rumm wrote:
On 14/06/2015 13:55, Bob Eager wrote:
On Sun, 14 Jun 2015 05:20:35 -0700, spuorgelgoog wrote:

On Sunday, 14 June 2015 13:03:03 UTC+1, John Mulrooney wrote:
I'm starting to install some interlinked smoke and heat alarms. Can
they use L & N from different circuits, or sgould they have a
seperate dedicated one.

All alarms must be on the same circuit.

It doesn't have to be a dedicated alarm-only circuit and there are
good reasons for it not being so; but the alarms should then have
battery or capacitor back-up.

On a mixed use circuit you are likely to notice a supply failure more
quickly than if only the alarms are affected.

Or do what I do and put a prominent non-maintained emergency light on
the same circuit. Useful in its own right.

Yup that was my preferred solution as well. I also fitted a centralised
switch so that the alarms can be tested or silenced from one place
easily (since some are well out of reach on 10' high ceilings)

Thanks all inc. Tim & Adam, got the idea

John

--
John Mulrooney
NOTE Email address IS correct but might not be checked for a while.

On Sunday, 14 June 2015 17:08:02 UTC+1, ARW wrote:
If you do that then there should be a means of isolating the smokes whilst
still leaving the lights powered up.

Perhaps in theory, but I'm unhappy about having isolators on smoke alarms in case it's left off.

Anyway, I didn't fit an isolator as I used the smoke alarm circuit to back feed half the lights.

Owain

"Tim Watts" wrote in message
...
On 14/06/15 17:07, ARW wrote:
"Tim Watts" wrote in message
...

The must be on the same circuit and generally are put on a lighting
circuit (ground floor preferred) so that circuit trip is immediately
apparent (evening/night at least).


If you do that then there should be a means of isolating the smokes
whilst still leaving the lights powered up.


Is there a recommended way? I presume it should not be *too* easy?
Emergency key type test switch or just an out of the way normal isolator?


For a RCD protected circuit I would suggest a double pole key switch. For a
non RCD circuit (16th edition) an unswitched fused spur would be fine on a
TN supply.

--
Adam

On 14/06/15 19:00, Tim Watts wrote:
On 14/06/15 17:07, ARW wrote:
"Tim Watts" wrote in message
...

The must be on the same circuit and generally are put on a lighting
circuit (ground floor preferred) so that circuit trip is immediately
apparent (evening/night at least).


If you do that then there should be a means of isolating the smokes
whilst still leaving the lights powered up.


Is there a recommended way? I presume it should not be *too* easy?
Emergency key type test switch or just an out of the way normal isolator?

My BCO insisted I have a seperate smoke alarm circuit. They have green
LEDS in em - obvious when the wife has left the bath running and tripped
em again by letting water cascade through the floor


--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.

On 14/06/15 19:55, ARW wrote:


For a RCD protected circuit I would suggest a double pole key switch.
For a non RCD circuit (16th edition) an unswitched fused spur would be
fine on a TN supply.


OK -

Can I just query the rationale though? I was just thinking that it would
not shut them up as they've all got batteries of some sort and if it's a
matter of replacing them, most of the ones I know of plug into a base.

Sorry for being thick - I assume there is a good reason, just not one I
know of!

On Sun, 14 Jun 2015 14:28:40 +0100, John Rumm wrote:

Or do what I do and put a prominent non-maintained emergency light
on
the same circuit. Useful in its own right.

Yup that was my preferred solution as well.

Good idea, there is a non-maintiand emergenct light above the strairs
but I think it's on a lighting circuit not the dedicated smokes one.
I'm not going to play just at the moment...

I also fitted a centralised switch so that the alarms can be tested or
silenced from one place easily (since some are well out of reach on 10'
high ceilings)

Yep, ours has "locate", "test" and "silence".

No one has mentioned that the smokes wiring ought to be done in red
three core and earth. I'd also do it as a seperate circuit for the
smokes only even if the power comes of a lighting circuit rather tahn
just picking up the nearest bit of lighting power.

--
Cheers
Dave.

On 15/06/2015 00:52, Dave Liquorice wrote:
On Sun, 14 Jun 2015 14:28:40 +0100, John Rumm wrote:

I also fitted a centralised switch so that the alarms can be tested or
silenced from one place easily (since some are well out of reach on 10'
high ceilings)

Yep, ours has "locate", "test" and "silence".

Yup, that's the beastie - three rocker switches on a single faceplate.

No one has mentioned that the smokes wiring ought to be done in red
three core and earth. I'd also do it as a seperate circuit for the

Should be 3&E certainly... not sure if the colour requirement applies to
domestic though?

smokes only even if the power comes of a lighting circuit rather tahn
just picking up the nearest bit of lighting power.



--
Cheers,

John.

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

"Dave Liquorice" wrote in message
ll.co.uk...

No one has mentioned that the smokes wiring ought to be done in red
three core and earth.

Possibly because it is not required for a grade D LD2/LD3 domestic
install:-)

One of the troubles with smoke detectors is that there are 3 different regs
to refer to

You have
BS 5839-6
BS 7671
and Part B of the building regs.

--
Adam

"ARW" wrote in message
...
"Dave Liquorice" wrote in message
ll.co.uk...

No one has mentioned that the smokes wiring ought to be done in red
three core and earth.

Possibly because it is not required for a grade D LD2/LD3 domestic
install:-)

One of the troubles with smoke detectors is that there are 3 different
regs to refer to

You have
BS 5839-6
BS 7671
and Part B of the building regs.

Oh and there is the NICEIC who make up whatever rules they want to when
doing inspections.



--
Adam

On Mon, 15 Jun 2015 18:30:16 +0100, ARW wrote:

No one has mentioned that the smokes wiring ought to be done in
red
three core and earth.

Possibly because it is not required for a grade D LD2/LD3 domestic
install:-)

I did say "ought" not "must". B-) Makes sense to me to use red so
it's obvious its the smokes circuit when faced with a gert bundle of
cables.

Isn't the red PVC stuff a bit tougher than bog standard grey?

--
Cheers
Dave.

"Dave Liquorice" wrote in message
ll.co.uk...
On Mon, 15 Jun 2015 18:30:16 +0100, ARW wrote:

No one has mentioned that the smokes wiring ought to be done in
red
three core and earth.

Possibly because it is not required for a grade D LD2/LD3 domestic
install:-)

I did say "ought" not "must". B-) Makes sense to me to use red so
it's obvious its the smokes circuit when faced with a gert bundle of
cables.

Isn't the red PVC stuff a bit tougher than bog standard grey?

Do you mean red fp cable?

If you want a ******* cable to work with try the LSZH ones.

Cheers

--
Adam

In article ,
ARW wrote:
"Dave Liquorice" wrote in message
ll.co.uk...
On Mon, 15 Jun 2015 18:30:16 +0100, ARW wrote:

No one has mentioned that the smokes wiring ought to be done in
red
three core and earth.

Possibly because it is not required for a grade D LD2/LD3 domestic
install:-)

I did say "ought" not "must". B-) Makes sense to me to use red so
it's obvious its the smokes circuit when faced with a gert bundle of
cables.

Isn't the red PVC stuff a bit tougher than bog standard grey?

Do you mean red fp cable?

If you want a ******* cable to work with try the LSZH ones.

Pyro is even more fun.

--
Please note new email address:

On Monday, 15 June 2015 18:33:28 UTC+1, ARW wrote:
Oh and there is the NICEIC who make up whatever rules they want to when
doing inspections.

And then the Scottish Government housing office, and the local council housing office, and the local fire service, etc etc who all make up their own versions too.

Owain

On 15/06/2015 20:31, ARW wrote:
"Dave Liquorice" wrote in message
ll.co.uk...
On Mon, 15 Jun 2015 18:30:16 +0100, ARW wrote:

No one has mentioned that the smokes wiring ought to be done in
red
three core and earth.

Possibly because it is not required for a grade D LD2/LD3 domestic
install:-)

I did say "ought" not "must". B-) Makes sense to me to use red so
it's obvious its the smokes circuit when faced with a gert bundle of
cables.

Isn't the red PVC stuff a bit tougher than bog standard grey?

Do you mean red fp cable?

If you want a ******* cable to work with try the LSZH ones.

Cheers


Oh yes... Low Smoke Zero Halogen.....