Replacing mains fire alarms

[Awsm132]

Hi there am new to this forum so please excuse me if I'm not doing things right!

Have just moved in to a new house which is about 15 years old and the mains fire alarms are missing,

So I went to screw fix and bought two new ones am unsure on correct wires to match up?

The house smoke alarm wires that are connected to a connector are red, blue, yellow and earth

The new alarm wires are blue,brown and white!

What colours do I match up? Thanks a lot

 

[Iggifer]

Are the terminals on each base not labelled?

 

[Taylortwocities]

Are you replacing all of the alarms in the house? You cannot mix different makes.

At the first alarm you should have two cables, a twin and earth and a 3 core and earth. Yes?

If so, simply follow the diagrams that come with the alarms.

If not, you'll need a multimeter to decide which is the live, neutral and interconnect connections.

Remember that the conductor colours are just, well, colours. there is no specific convention that states what a yellow wire is used for, it is up to the installer.

 

[Awsm132]

The new alarm instructions say the brown is live, blue is neutral and white is the interlink between the alarms! So I connected the white to the yellow wire in the house, the brown to the red and the blue to blue! But when I connect both alarms and turn power back on the alarms sound and don't stop

 

[Awsm132]

Are you replacing all of the alarms in the house? You cannot mix different makes.

At the first alarm you should have two cables, a twin and earth and a 3 core and earth. Yes?

If so, simply follow the diagrams that come with the alarms.

If not, you'll need a multimeter to decide which is the live, neutral and interconnect connections.

Remember that the conductor colours are just, well, colours. there is no specific convention that states what a yellow wire is used for, it is up to the installer.

Yea have two new alarms of same model that is correct at first alarm there is cable in and cable to next alarm the issue is when I connect it up both alarms sound

 

[PrenticeBoyofDerry]

On smokes
Brown=Live
Blue=Neutral
White=Interlink
On you house wiring, this would depend on the installer, but I would expect
Red=Live
Blue=Neutral
Yellow=Interlink.

I would be interested which type of smoke alarms you purchased and what locations they are serving?
I hope you have purchased opticals for hall and landing.

After reading your recent post, it is possible that the installers has not connected the cables as normal, time for test equipment!

 

[endecotp]

Have you looked at how the colours are wired up where it connects to the consumer unit (or wherever) ?

 

[PrenticeBoyofDerry]

Have you looked at how the colours are wired up where it connects to the consumer unit (or wherever) ?

It is doubtful that would indicate how the interlink is formed!
It is likely that red is live and yellow neutral and blue interlink, but advisable that some dead testing is made prior to making live.
The smokes are probably connected to the lighting circuit anyway, so that may be a first port of investigation.

 

[Taylortwocities]

you'll need a multimeter to decide which is the live, neutral and interconnect connections.
.

Maybe I should have said confirm which is the live, neutral and interconnect connections.

 

[PrenticeBoyofDerry]

What happens when just the one is wired up, if they both go off when both connected?
Have you checked that there is not a test button fault, such as jammed in test mode.

 

[endecotp]

Have you looked at how the colours are wired up where it connects to the consumer unit (or wherever) ?

It is doubtful that would indicate how the interlink is formed!

Well if he looks inside e.g. a ceiling rose and find that one of the colours is not connected, that is probably the one being used as the interlink.

 

[ban-all-sheds]

But when I connect both alarms and turn power back on the alarms sound and don't stop

That sort of thing is one of the hazards of doing wiring by guesswork.

But cheer up, it could have been worse. Other possible outcomes of connecting wires to see what happens, hoping that the right things happen, are permanent damage to equipment and injuries to people.

 

[PrenticeBoyofDerry]

Have you looked at how the colours are wired up where it connects to the consumer unit (or wherever) ?

It is doubtful that would indicate how the interlink is formed!

Well if he looks inside e.g. a ceiling rose and find that one of the colours is not connected, that is probably the one being used as the interlink.

It is not really conventional to run the three core and earth to a light fitting, I would have thought that it would be more logical and safer to just run a T&E to the first base unit, then TC&E between each base unit.

 

[endecotp]

It is not really conventional to run the three core and earth to a light fitting, I would have thought that it would be more logical and safer to just run a T&E to the first base unit, then TC&E between each base unit.

Right, but that's not what he is describing; apparently he is only seeing "red blue yellow earth" in the "house wiring". Hence my suggestion to find the other end of the first of those, where presumably it is connected to e.g. the lighting circuit or its own circuit in the CU.

Or maybe he has not described it fully, and there is conventionally-coloured T&E going to the first of the bases. But that's not what he has said.

 

[PrenticeBoyofDerry]

Are you replacing all of the alarms in the house? You cannot mix different makes.

At the first alarm you should have two cables, a twin and earth and a 3 core and earth. Yes?

Yea have two new alarms of same model that is correct at first alarm there is cable in and cable to next alarm the issue is when I connect it up both alarms sound

The OP seems to have agreed with the above statement, so I can only assume that there is a supply via T&E. Unfortunately the OP now needs to do some testing rather than guessing, but has gone quiet on the subject!