Smoke Alarm Circuit Specification

[daiking]

Following on from my questions, I am a lot clearer on things so I'd like to start a fresh thread focussed on a design.

 

Smoke Alarms 1 & 2 were installed (badly) before the extension (shown by the dashed line) was built. They are connected by T&E not 3&E so were never interlinked even though they should be. I'm trying to find out the requirements I need to meet i.e. Buiding Regs and not break the bank. Consumer unit is under the cupboard under the stairs and the alarms have their own MCB switch. Alarm 1 has a JB with a cable in and out (floor void) and Alarm 2 has a single cable to it (in loft).

 

So it looks like the Consumer Unit feed alarm 1 which feeds alarm 2. In doing some work in the house I now have an 'easy' route from alarm 1 to alarm 2 to replace the joining cable with 3&E to make them interlinked. But this does not address the issues with other alarms I may or may not require.

 

The potential alarms are shown in the bubbles, 3, 4 & 5. The kitchen will require an alarm, shown as alarm 3 and I can get access to the normal ceiling area shown from above with 'moderate' difficulty. Nothing else planned for this open plan area.

 

I'm not sure if I require an alarm in the utility but seeing as it has the boiler, washing machine and tumble dryer and its under my bedroom, I think it should. This alarm has 'moderate' access back to the consumer unit but 'difficult' to link it to one of the other alarms.

 

Alarm 5 I am not sure if I require but it is another lounge area and has a gas fire. Again there is moderate access to installing in this room and linking to the other.

 

Also, it would be nice to have a reset switch, shown S1 by the open plan room. Will one downstairs be enough? Do I require S2 shown upstairs?

 

Alarm types to be confirmed once layout and requirement for alarms is decided. Also there's the loft(s) I suppose but no plans for those at the moment. 

 

Note, I don't intend doing the terminations myself now but I may have to put wires in the correct locations myself now for a professional to terminate at a later stage.

 

 

Edited August 8, 2016 by daiking

[daiking]

I'm due to cover up smoke alarm 1 very soon so will be taking the opportunity to put some cable in the floor and hope it's suitable. 

 

As before, the T&E from the CU is existing and goes alarm 1. From there, the 3&E will go to alarm 5, back to the space by alarm 1 out to alarm 3 and back, then up through a cavity wall to the loft to alarm 2 as shown. Approximately 33m which should be ok for 5 smoke alarms on 1mm2 cable. 

 

The link between 2 and 4 will be trick and worked out later. 

 

 

If I moved alarm 1 about 500mm so it was under the landing not the bathroom floor, I could maybe come back to this later although the I would need to leave a cable or drawstrings in place between 1 and 2 or I find another route up to the loft from 3 up the bedroom wall or something.

 

 

[daiking]

From further investigations I am confident I have identified the "power" lead to the first alarm and the lead between the two existing alarm positions. I've disconnected this joint between them but to keep things safe I have terminated the end of each lead in separate old fashioned junction boxes and switched off the MCB. This is under the carpeted landing so reasonably accessible at the moment.

 

I've also sort of laid a length of 3&E as described above so the bathroom floor should not need raising for this issue at least. I'll look for alarms themselves in a couple of weeks.

Edited August 16, 2016 by daiking

[daiking]

I have now managed to, during other works, run a 3&E cable from point 1 to point 5 to point 3 to point 2. I could have the semblance of a functioning alarm system at this rate. Just need to decide detector type and position of a couple, 3 being the most confusing, on the 'soffit' from the kitchen vaulted ceiling.

 

Number 4 is tricky and I don't know how to get to it as it is in the new part of the house and will be messy to get at. I don't think its needed but I would prefer one in there as the master bedroom is above and the gas boiler, washing machine and tumble dryer are all int here.

[ProDave]

Check manufacturers instructions. some are happy to be on a vertical or sloping wall, some not. Keep at least 300mm from a corner or a light fitting.

 

If you can't get a link cable from the old to new part of the house, use radio link bases to link them. Then you only need power to the alarm in the old part of the house.

 

Not the cheapest, but Aico are my favourite make.
 

[daiking]

1 hour ago, ProDave said:

Check manufacturers instructions. some are happy to be on a vertical or sloping wall, some not. Keep at least 300mm from a corner or a light fitting.

 

If you can't get a link cable from the old to new part of the house, use radio link bases to link them. Then you only need power to the alarm in the old part of the house.

 

Not the cheapest, but Aico are my favourite make.
 

 

Aico definitely seems to be the way to go.  I don’t want to go wireless because of the cost and the wireless thing when I’m sure an electrician could easily figure something out – up through the original wall cavity into the loft is probably the best bet at the moment to connect to location 2.

 

I’ve got the Aico fitting instructions for locating near walls and on slopes etc  but kitchens should be heat sensors not optical/ionisation sensors and I’m not sure that it will be effective in the planned location although it will be within 5m  and don’t really want to run a cable round in trunking to another location.

 

And I need to think about locating a reset/kill switch…

[ProDave]

I have always managed to get Aico RF bases for about £20-£30 each on ebay. That's a couple of hours of a sparky's time trying to fish a cable through a long impossible route. Sometimes it is the cheapest option.
 

[Temp]

Do the Aico support a reset/kill switch? Wonder if I can add one to mine.

 

In case it matters, I think you can only interlink alarms of the same make/model. 

 

[Onoff]

22 minutes ago, Temp said:

Do the Aico support a reset/kill switch? Wonder if I can add one to mine.

 

In case it matters, I think you can only interlink alarms of the same make/model. 

 

 

Good chance:

 

https://www.eielectronics.com/downloads/accessories-manuals.html?download=179:accessories-manuals

[daiking]

3 hours ago, ProDave said:

I have always managed to get Aico RF bases for about £20-£30 each on ebay. That's a couple of hours of a sparky's time trying to fish a cable through a long impossible route. Sometimes it is the cheapest option.
 

 

That's why its a job for me and hopefully I won't need a sparky for this. There is already a cable (T&E) from the CU for smokes. 

 

1 hour ago, Temp said:

Do the Aico support a reset/kill switch? Wonder if I can add one to mine.

 

In case it matters, I think you can only interlink alarms of the same make/model. 

 

 

AFAIK Yes. 

[daiking]

When wiring the alarms in this fashion:

https://www.aico.co.uk/technical-support/basic-wiring-diagrams/

 

Does one use junction boxes with a spur to each alarm or can you run 2 cables into each terminal in the base and forego any other joint/junction paraphernalia?

 

[ProDave]

8 minutes ago, daiking said:

When wiring the alarms in this fashion:

https://www.aico.co.uk/technical-support/basic-wiring-diagrams/

 

Does one use junction boxes with a spur to each alarm or can you run 2 cables into each terminal in the base and forego any other joint/junction paraphernalia?

 

You can comfortably get two cables into an aico terminal box. If you are really tidy, and use 1mm (not 1.5) you can get 3 in if you want to make a spur.
 

[daiking]

4 minutes ago, ProDave said:

You can comfortably get two cables into an aico terminal box. If you are really tidy, and use 1mm (not 1.5) you can get 3 in if you want to make a spur.
 

 

Thanks that's good to know. I'm not doing this imminently but the cables themselves will soon be inaccessible. 

 

So so if I just make a small hole in the ceiling and poke a loop of 3&E through it for now, it will be ok?

[ProDave]

29 minutes ago, daiking said:

 

Thanks that's good to know. I'm not doing this imminently but the cables themselves will soon be inaccessible.

 

So so if I just make a small hole in the ceiling and poke a loop of 3&E through it for now, it will be ok?

Yes.

 

Just bear in mind, if you are wanting to position the sensor on the ceiling to line up with something else, that the cable entry into an Aico sensor is NOT in the middle, but close to the edge. So if exact position is important, the cable needs to come out of the ceiling about 5cm out from where the centre of the sensor will be.
 

[daiking]

In an effort to get BR sign off, alarms, hallway and landing are now installed. Aico ei146. Everything seems to work correctly for the first time. Just need some blue insulation tape to identify the grey 3&E wire as the neutral.

 

Effectively a like for like replacement of existing alarms which were defunct anyway. Used the original idiot's T&E cable to first alarm so I've not touch anything near the CU and a new 3&E cable between alarms for the interconnect. I routed it to allow for the placement of other alarms and a control switch if desired/required at some point.