NEST Protect Installation Advice needed

[sipxstream]

Hello chaps,

We've finally moved into our new house last week, and I need a bit of advice please on the installation of a NEST Protect smoke/CO2 alarm in my garage.

I have 2 incoming power circuits into my rather long garage:

1. One for lights at the front of the garage, taken from the 1st floor circuit using 2-plate method (Power at the switch);
2. The other circuit directly coming from the CU that powers the garage sockets and is then split off mid-way into an FCU for lights at the back the garage. The FCU acts like a light switch.

I need to install the NEST somewhere in the middle.

I can cut into the 2.5mm cable between sockets and take a junction from there which will use a lot less cable, or I can take a feed from the switch but will use more cable.

Would one be better than the other?

If I took a permanent live and neutral from the 2.5mm power cable and used a 1.5mm cable for the NEST, would I need to use an FCU?

Thank you.

 

[EFLImpudence]

We've finally moved into our new house last week, and I need a bit of advice please on the installation of a NEST Protect smoke/CO2 alarm in my garage.

Presume you mean CO but why? Is the boiler in the garage?

Would one be better than the other?

No.

If I took a permanent live and neutral from the 2.5mm power cable and used a 1.5mm cable

1mm² will be hugely oversized; no need for another 50%.

for the NEST, would I need to use an FCU?

A switch will be handy so may as well.

 

[sipxstream]

Presume you mean CO but why? Is the boiler in the garage?

Ah, yes! You presume correctly - CO... Sorry...

Boiler is in the kitchen, not in the garage. The reason I went for another NEST is that I already have two installed in the house. And the reason why I need to install a smoke alarm in the garage is because I will have a stack IT servers running 24/7, as well as my LiFEPO4 batteries once my solar installation is finished.

1mm² will be hugely oversized; no need for another 50%.

Great, even cheaper!

A switch will be handy so may as well.

I'll add one just in case and pop a 3A fuse in there.

Awesome, thanks for the advice.

 

[sipxstream]

So my plan of action is this:

Between two of the sockets, I'll safely cut into the 2.5mm² cable. I'll attach both legs of the cable into Wago 3-terminal blocks and add a 3rd cable for the new FCU. I'll take the load for the NEST using 1mm² cable from the FCU, and hopefully that'll be that...

Now, the NEST is double-insulated, so there's no available terminal on the NEST for a CPC, so I'm a bit stumped as to what to do. There'll obviously be a connection for the CPC within the FCU, so am I best to just attached a Wago to the other end to safely terminate it? From the short length between the FCU and the NEST, I guess I could attempt to pull out the bare CPC conductor, would this be advisable?

Once all connections are teminated correctly, I'll add the Wago joins into a Wago box and zip-tie it all up to be maintenance free.

Please let me know if I'm incorrect, or have overlooked anything.

Many thanks.

 

[RandomGrinch]

Now, the NEST is double-insulated, so there's no available terminal on the NEST for a CPC,

Run a 2 core flex from the FCU to the Nest?

 

[sipxstream]

Run a 2 core flex from the FCU to the Nest?

Fab, thanks for the advice. I'll have a look for a 2-core flex on Screwfix/Toolstation

 

[EFLImpudence]

How far away is a socket?

Can you not use a socket instead of a junction box?

 

[sipxstream]

How far away is a socket?

Can you not use a socket instead of a junction box?

The socket on the wall is approximately 1.5 meters from the centre of the ceiling where is the NEST is to be placed.

 

[EFLImpudence]

How far is where the junction box will be?

 

[sipxstream]

I've taken a pic (please excuse the mess) and added some crude arrows and text boxes to explain where the two sockets are and where I intend to make the cut for the new junction.

 

[sipxstream]

Thinking about it, instead of cutting where I originally intended to cut, can I take a feed from Socket 1 directly into a new FCU? If I'm not mistaken, this would be classed a spur off of Socket 1 - correct?

 

[sipxstream]

Run a 2 core flex from the FCU to the Nest?

This is the only 2-core flex that Screwfix has and it's not that expensive either for a 10m coil... https://www.screwfix.com/p/time-3182y-white-2-core-1-5mm-flexible-cable-10m-coil/905jy

 

[EFLImpudence]

Thinking about it, instead of cutting where I originally intended to cut, can I take a feed from Socket 1 directly into a new FCU? If I'm not mistaken, this would be classed a spur off of Socket 1 - correct?

Yes, that is what I had in mind.

As it turns out the socket is not nearer than the junction box would be but that doesn't matter; it is better not to have JBs if they can be avoided.

 

[EFLImpudence]

This is the only 2-core flex that Screwfix has and it's not that expensive either for a 10m coil... https://www.screwfix.com/p/time-3182y-white-2-core-1-5mm-flexible-cable-10m-coil/905jy

You can just use a bit of T&E. Connect the CPC at the socket and terminate safely out of the way at the other end.

 

[sipxstream]

Awesome, thanks for your help; I'll get everything I need and make a start on it this weekend.

Just one more question, which might not even matter, but i'll ask anyway just in case:

Should the FCU be placed close to the NEST, or can it be placed it nearer to the socket?