Mains operated interconnected smoke alarm

[loz2754]

I also thought there was a "heat resistant" type 3 core and earth cable. Perhaps I should use that for the interconnect?

No, the correct cable to use is PVC twin and earth, 1mm².

Twin and earth for the supply to the first smoke alarm, and 3 core and earth for the links from the first smoke alarm to the 2nd, from the 2nd to the 3rd, etc.

 

[Neptune]

No, the correct cable to use is PVC twin and earth, 1mm².

Twin and earth for the supply to the first smoke alarm, and 3 core and earth for the links from the first smoke alarm to the 2nd, from the 2nd to the 3rd, etc.

I was wondering if there is a heat resistant version of each of these cables or should I be using the conventional type?

 

[Dartlec]

I was wondering if there is a heat resistant version of each of these cables or should I be using the conventional type?

You can get LSF (Low Smoke and Fume) twin and earth, but it's not necessary. Normal 3 core and earth will be fine for interconnected smoke alarms in your sort of application.

 

[DJAndy]

Once, I have confirmed the presence of permanent live in the ceiling rose I will use the trunking and clips mentioned to complete this task.

If there is a ceiling void you might be able to use cable rods or similar to get a cable from your light fittings to the alarms without trunking. Takes longer but worth the effort.

 

[Neptune]

Morning Guys,
I've been advised that I require Grade D LD 2 interlinked mains wired detectors.
Can someone please advise if these would suffice:

Aico Ei141RC Easi-fit Ionisation Smoke Alarm 230V + 9V Alkaline Battery Back-up | Toolstation

• Long life ionisation sensor more responsive to flaming fires (paper, clothing) • Easi-fit base • RadioLINK base provides wireless interconnection • Low battery warning • Test/silence button • Fit in bedrooms BS EN 14604:2005 KM 552831. This alarm conforms to the latest British...

www.toolstation.com

Aico Ei144RC Easi-fit Heat Alarm 230V + 9V Alkaline Battery Back-up - https://www.toolstation.com/aico-ei144rc-easi-fit-heat-alarm/p49808 (kitchen)

I have also seen "optical" devices and don't understand the difference between these and the above ionisation ones.

Finally, are there any good practices in how the conduit should be laid out on the ceiling? For instance, should I go along the outer edge of the ceiling and then cut across to the detector or should the trunking go in straight lines across the ceilings, from one room to another.

I really appreciate your help with this.

 

[Strima]

You would need to buy the radio link bases with those. I’ve used them in the past and they’re very easy to instal and set up.

Where possible take the supply from the nearest light fitting, read the manufacturers instructions but generally they should be placed more than 300mm from any other fixture or wall. The bases are designed to accept 25x16 trunking and it would be advisable to use fire clips to support the cables.

 

[Neptune]

You would need to buy the radio link bases with those.

I was planning to hard wire the interconnect. Presumably the radio link bases wont be required in that case?

Also, can you please confirm that these meet the Grade D LD2 standard as I couldn't find this info anywhere.

 

[Neptune]

3 core and earth for the links from the first smoke alarm to the 2nd, from the 2nd to the 3rd, etc.

Is 1.5mm 3 core and earth required for this?

 

[DPG]

Is 1.5mm 3 core and earth required for this?

You'll need 3 core for the link.

 

[brianmoooore]

You'll need 3 core for the link.

Dangerous advice to a DIYer!!
T&E is '3 core'. 4 core, otherwise known as 3 & E is required.

 

[Dartlec]

I was planning to hard wire the interconnect. Presumably the radio link bases wont be required in that case?

Also, can you please confirm that these meet the Grade D LD2 standard as I couldn't find this info anywhere.

Grade D of the standard basically means mains powered with backup battery.

As of the 2019 BS 5839 standard there are now two levels though -

• Grade D1: the stand-by supply must be tamper-proof and last the full life of the alarm
• Grade D2: the stand-by supply is user-replaceable and will not last the full life of the alarm

So the one you've linked with a 9V battery would be Grade D2. Grade D1 is the type with a tamper proof lithium rechargeable battery installed.

Part B of the building Regulations suggests that Grade D2 is acceptable, so you would be covered.

LD2 then refers to where the alarms cover...

• LD2 – A system incorporating detectors in all circulation spaces that form part of the escape routes from the premises, and in all rooms or areas that present a high risk of fire to occupants.

As I understand it that means staircases or hallways (circulation spaces - one per level unless the hallways are long), with a heat alarm in the kitchen. Some guidance suggests the main lounge as well, but I don't believe that is set in stone - if there was an open fire in there then it could be said it presents a high risk of fire....

Optical or Ionisation are the different types of methods of detection, and each work better for certain types of fires (smouldering/flaming, etc). In general, optical is less prone to false alarms and are now the recommended option. They are less sensitive to smoke from toast, or steam from a shower room, though they are not recommended for use in a kitchen - a heat alarm is the preferred option there)

Ionisation alarms might be suitable for upstairs landings or stairwell - they are faster to react to fast flaming fires from paper, wood etc.

As previously mentioned, if you run the wiring in trunking, then you should use fire-rated cable clips to ensure against premature collapse of the wiring in the event of a fire. This applies to all trunking and cabling, not specifically ones supplying fire alarms though.

There is no specific 'right' way to run trunking on the ceiling - as long as the cabling within it is protected against premature collapse. It may be easier/neater to run around the edges, or the shorter direct route may be preferred.

3 Core and Earth is what you'll need for hard-wiring between then, though 1mm would be fine too.

 

[DPG]

Dangerous advice to a DIYer!!
T&E is '3 core'. 4 core, otherwise known as 3 & E is required.

Apologies, should have been clearer. Was agreeing that 3 core and earth is needed rather than twin and earth.

 

[i=p/u]

I smell smoke, good luck.

 

[Neptune]

Couple of further questions on this please:

- When slotting the trunking into the smoke detector, does some of the top and bottom section of the trunking disappear into the detectors base? I am trying to determine how neat my cut on the trunking needs to be.

- Secondly, when I am passing through walls (brick) as I go from the ceiling from one room to another, what are your recommendations on making this entry? I have an SDS drill but thought that it may not work right in the corner of the ceiling and wall.

- Thirdly, whilst the smoke detectors need to be daisy chained with the 3 core and earth cable, how do I install an Aico Fire Control Switch? Remote Control Alarm Switch 230v Mains - https://www.cef.co.uk/catalogue/products/1148678-remote-control-alarm-switch-230v-mains?gclid=16b5a446064114559754c4ddd79e91a2&gclsrc=3p.ds&msclkid=16b5a446064114559754c4ddd79e91a2

Is this just like another smoke detector in the sense that it should be included in the daisy chain i.e. one cable in and one out to the next detector?

Thanks for your continued support.

 

[Mike Johnson]

You need to get hold of "Electrical Contractors Handbook" Guides & Publications - Aico - https://www.aico.co.uk/technical-support/guides-publications/ free from Aico as a download or by post.

 

[Lister1987]

You need to get hold of "Electrical Contractors Handbook" Guides & Publications - Aico - https://www.aico.co.uk/technical-support/guides-publications/ free from Aico as a download or by post.

Also available as an app on Android

Aico Handybook - Apps on Google Play

For Electrical Contractors

play.google.com

 

[Lister1987]

Smoke alarms are not covered by an EICR, other than the mains feed.

Very much dependent on the Inspector. If you have working knowledge of 5839-6 then you can code it against 560.10, adding on relevant clauses in 5839-6 to bolster the inclusion in scope. BS7671 says in the early pages it is not exhaustive and can be supplemented by other standards, here is a perfect example of that in action.

 

[Neptune]

I do plan to go through the suggested booklet but would really appreciate a few pointers on the below as I am pushed for time.


When slotting the trunking into the smoke detector, does some of the top and bottom section of the trunking disappear into the detectors base? I am trying to determine how neat my cut on the trunking needs to be.

- Secondly, when I am passing through walls (brick) as I go from the ceiling from one room to another, what are your recommendations on making this entry? I have an SDS drill but thought that it may not work right in the corner of the ceiling and wall.

- Thirdly, whilst the smoke detectors need to be daisy chained with the 3 core and earth cable, how do I install an Aico Fire Control Switch? Remote Control Alarm Switch 230v Mains - https://www.cef.co.uk/catalogue/products/1148678-remote-control-alarm-switch-230v-mains?gclid=16b5a446064114559754c4ddd79e91a2&gclsrc=3p.ds&msclkid=16b5a446064114559754c4ddd79e91a2

Is this just like another smoke detector in the sense that it should be included in the daisy chain i.e. one cable in and one out to the next detector?


Thanks in advance

 

[Mike Johnson]

I am sorry you are pushed for time, but you need to do a little homework yourself: https://04646a9cf351cc0d3888-b8b406...49ac64a455d7d50c7c919cd8e8e8d5.pdf?1570024787

 

[Neptune]

Thanks guys. I’ve read the install doc but don’t see any guidance on the below.


When slotting the trunking into the smoke detector, does some of the top and bottom section of the trunking disappear into the detectors base? I am trying to determine how neat my cut on the trunking needs to be.

- Secondly, when I am passing through walls (brick) as I go from the ceiling from one room to another, what are your recommendations on making this entry? I have an SDS drill but thought that it may not work right in the corner of the ceiling and wall.

I would appreciate your advice on this please.