Fitting an additional smoke alarm to existing circuit.

[rubberneck]

Hello.
I've trawled through the forum looking for the answer to my query but to no avail, so here goes...

I have an existing mains powered interlinked smoke alarm system in my house , comprising of 2 smoke alarms and a heat alarm. These are powered from the first floor lighting circuit and were fitted when the house was rewired about 4 years ago.

I've converted the loft and need to fit a smoke alarm in there too. My question is this:

Can I fit the additional alarm by spurring off one of the existing smoke alarms, whichever is the closest/most convenient, with 3+E 1.0mm cable.

The alarms are AICO brand.

Many thanks in advance.

Gordon

 

[Gutterball]

http://www.aico.co.uk/Mains-Powered-RadioLINK-Alarms.html

 

[PrenticeBoyofDerry]

My question is this:

Can I fit the additional alarm by spurring off one of the existing smoke alarms, whichever is the closest/most convenient, with 3+E 1.0mm cable.

The alarms are AICO brand.

Logically you would go to the last on circuit, but you could take a feed from the nearest, providing there is room to terminate the cable.
Remember cable must be installed in permitted safe zones and if buried less than 50mm without mechanical protection, 30mA RCD protection will be required if not already on circuit.

 

[rubberneck]

http://www.aico.co.uk/Mains-Powered-RadioLINK-Alarms.html

Thanks for the response.

I had considered those wireless alarms but pricing them up was quite "alarming". I would need to buy 2 wireless bases in addition to the extra alarm unit itself.

The cable run from the existing unit to the proposed position is very easy to access and as I have a reel of 3+E available I was hoping to just use the standard hardwired system.

 

[rubberneck]

My question is this:

Can I fit the additional alarm by spurring off one of the existing smoke alarms, whichever is the closest/most convenient, with 3+E 1.0mm cable.

The alarms are AICO brand.

Logically you would go to the last on circuit, but you could take a feed from the nearest, providing there is room to terminate the cable.
Remember cable must be installed in permitted safe zones and if buried less than 50mm without mechanical protection, 30mA RCD protection will be required if not already on circuit.

Thanks for taking time to respond.
Getting a cable run from the last on the circuit is a bit of a bind and I haven't got a long enough length of cable!
I am hoping that there is room to terminate in the closest unit-I imagine it will be very confined with the additional cable in there. If i'm struggling to fit the cables in I may take the power supply from the nearest light fitting - this is 600mm away from the proposed alarm position(on the same circuit, which is protected) and just run a single cable for the interlink from the nearest existing alarm.

Many thaks
Gordon

 

[PrenticeBoyofDerry]

But you stated that downstairs lights powered the smokes, it would not be advisable to have the smokes powered by two devices at the board. If the jobs worth doing, worth doing well.
Could also cause issues with imbalance of RCDs

 

[rubberneck]

But you stated that downstairs lights powered the smokes, it would not be advisable to have the smokes powered by two devices at the board. If the jobs worth doing, worth doing well.
Could also cause issues with imbalance of RCDs

The light in the loft is on the same circuit as the first floor. The ground floor lights are on a separate circuit. Hope this clarifies things.

 

[sparkwright]

http://www.aico.co.uk/Mains-Powered-RadioLINK-Alarms.html

This is radio link stuff.

Since you are doing a loft conversion, and since you almost certainly have a smoke detector upstairs, probably the landing; and since you have to pass other cables up to the loft DON'T BOTHER WITH THE RADIO LINK STUFF and RUN FROM THE EXISTING SMOKES IN 3 CORE 1.0 mm AND EARTH LIKE YOU HAVE ALREADY SUGGESTED.

 

[Lectrician]

Obviously don't mix brands, stick with Aico. You can tee off where ever you wish. Brown as live, grey (sleeved blue) as neutral, and black as interlink. Or if your existing wiring is done using different colours, I guess you should follow that (sleeved accordingly).

 

[Gutterball]

if you need more space to terminate the wires in the alarm, fit a 1 gang plasterboard box into the ceiling behind the alarm. and use it as a junction box.

 

[rubberneck]

if you need more space to terminate the wires in the alarm, fit a 1 gang plasterboard box into the ceiling behind the alarm. and use it as a junction box.

Would it be possible to insert a regular 4 terminal junction box in to the feed between 2 alarms and spur off that way? Is that what you mean?

 

[PrenticeBoyofDerry]

Would it be possible to insert a regular 4 terminal junction box in to the feed between 2 alarms and spur off that way? Is that what you mean?

The junction needs to be accessible for maintenance, inspection and testing, that is why a dry-lining box was recommend as the joints would be accessible on removing he smoke alarm mounting plate, so can be fitted above it. Any inaccessible joints requires to be made so they are considered maintenance free. There are maintenance free junction boxes available.
Some links below;
maintenance-free
dry-liner-box

 

[rubberneck]

There is readily available access to where the connection would be made (behind the eaves wall which is accessible via a door from the loft room) so I'm hoping to just tie-in to the circuit with a regular JB. I may just pull the cable from A to B and get a sparky in to do the final connection.

Thanks for all the advice you have been giving.