Mains operated interconnected smoke alarm

[Neptune]

I fitted these into my own house a few years ago when everything was ripped open and hence, am familiar with the process.
However, on this occasion I need to fit these into a property that I let out and I don't have access to the ceiling void on ground floor.

I was thinking about using trunking and wanted to check on what type of trunking is neat and recommended for this purpose. Also, how will this merge into the existing light pendant (standard light pendant hanging from the ceiling).

Finally, I assume that I will need to trunk to the switch and not light if that's where the permanent live is. If this is the case, how will the trunking merge into the existing light switch?

Never had to use trunking before. Thanks in advance.

 

[littlespark]

First check there isn’t a live and neutral at the light... older houses, this is where it was. Neutrals at switches is a fairly new thing.

from the light, you only need a live, neutral and earth to first smoke, then a 3 core and earth in a daisy chain to each other detector in turn. Live neutral earth and interconnecting cable.

some manufacturers offer 10 yr lithium detectors with radio signal interlink, for when you don’t want to disturb decoration,
Or mains with a radio module. Or the house can be a mix of wired and wireless...

 

[Strima]

AICO do a very good wireless range.

 

[loz2754]

AICO do a very good wireless range.

Also AICO bases have a cut out that accepts mini trunking.

 

[Dartlec]

One thing you will need to be careful of is the requirement for protection against premature collapse in the recent regulations.

Plastic trunking along a ceiling or high up on a wall could be liable to collapse during a fire, and cause potential risks to the tenants getting out, or fire fighters who are dealing with the situation.

There are metal clips available that fit inside plastic trunking to support the cabling in the event of the worst. I believe best practise is to fix them not with plastic rawl plugs, but with entirely metal fittings - you may be able to get metal screws into the joists for example.

In a standard hallway you may only need one or two of the clips on a run of trunking, with other fixings being normal rawl plugs if necessary

 

[littlespark]

^ another reason to go with battery radiolink versions.

 

[Neptune]

Thanks for all the responses. Really appreciate it.
How about the trunking detail when it connects to the light pendant?

Also, is there a certain type/profile of trunking you recommend? I noted the point re. metal clips.

 

[westward10]

You can get ceiling rose adapters for mini trunking it will drop the rose a bit but gives a neat solution.

Mini Trunking Ceiling Rose Adaptor White (Sold in 1's)

For use with mini trunking MMT1 and MMT2

www.cef.co.uk

As for internal metal fixings most are designed for 25 × 16 and upwards but if using 16 × 16 there are these although I have never tried them.

D-Line Safe-D Mini Trunking Spring Clips

Secure single cables with an outer diameter of up to 7mm by using these D-Line Safe-D spring clips. Suitable for use in PVC micro trunking or for direct-to-surface fitting – when secured with D-Fixings, the springs can hold cables in-situ at 970°C for up to two hours.Safe-D springs use...

www.toolstation.com

 

[MJPD29]

I would look into aico wireless base ones as well, nothing I hate more than mini trunking. Although sometimes it has its uses, I find it looks very amateur.

 

[i=p/u]

Also AICO bases have a cut out that accepts mini trunking.

Wash ur mouth out, yuck.

 

[loz2754]

Wash ur mouth out, yuck.

The OP has stated that he intends to use trunking to supply power to the smoke alarms from either a light or a switch, regardless of whether they're interconnected wirelessly, they still need power.

 

[pirate]

TBF, they can all be battery and radio-linked, at least the Aico ones can. I generally used to install the hall smoke as a wired, from a light, with a 10 year battery, and the rest just 10 year battery, radio linked. No mains wired for me now...why bother?
Unless your local BC have other ideas...
Better to have something that works, IMHO.

 

[loz2754]

TBF, they can all be battery and radio-linked, at least the Aico ones can. I generally used to install the hall smoke as a wired, from a light, with a 10 year battery, and the rest just 10 year battery, radio linked. No mains wired for me now...why bother?
Unless your local BC have other ideas...
Better to have something that works, IMHO.

This would be a Grade F system according to BS5839:6. You're quite correct in saying that some local building control/councils will not accept anything other than Grade D (mains interlinked).

However it should be ok in the private rented sector, as the actual legislation from October 2015 doesn't require mains OR interlinking, just smoke alarms on each floor.

 

[brianmoooore]

However it should be ok in the private rented sector, as the actual legislation from October 2015 doesn't require mains OR interlinking, just smoke alarms on each floor.

Another "C2 or C3" future thread in the making?

 

[loz2754]

Another "C2 or C3" future thread in the making?

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

 

[brianmoooore]

Not yet.

 

[loz2754]

Not yet.

I give your comment a C3. ?

 

[pirate]

To clarify, I was commenting from a Scottish perspective.

 

[loz2754]

To clarify, I was commenting from a Scottish perspective.

Ah. Different set of riddles rules.

 

[Neptune]

Thanks for all the responses. I really appreciate it.
My Local Authority has expressly stated that I need mains powered and cable interconnected smoke alarms. they do not approve the wireless system.

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.

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

Thanks again

 

[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.