Unknown Cable

[leevis]

Hi All
Been doing some work in my loft and I am going to be putting up a new ceiling and I have discovered a cable that I cannot identify. The problem is that when I was putting up new joists this one managed to get below so I need to splice it and reconnect it but I would like to know what it is. It is about a third of the size of some coaxial cable but I don't think that it is that. It is not a very solid cable ie I can move it quite easily. What I think it is is a link between the boiler and the thermostat.
Anyone got any ideas as to what I am looking at
Lee

 

[OwainDIYer]

what's the make and model of the boiler and thermostat?

Can you see the cable at either end?

 

[DaveHerns]

Burglar alarm system ? Phone wire ?

 

[leevis]

Definitely not burglar alarm, not thought about telephone, it could well be that!!! I know where that goes into one of the extensions upstairs (unused - who uses these anymore anyway apart from downstairs), I will check when I get home but you might be onto something.
The boiler is a Baxi combo boiler not sure of the model, will check later, also unsure of the thermostat but I will check this out also

 

[JohnD]

a photo, with a coin to show scale, might give a clue.

Meanwhile look around your phone, alarm and CH control cables.

 

[leevis]

I'll get some pics tonight when I get back, I have a feeling that it might terminate in an airing cupboard which is where both the boiler and the phone extension are so it might be one of those. If its the boiler control (which my money is on at the moment) can these be spliced/rejoined?

 

[JohnD]

boiler controls usually carry mains voltage, so are either flex (like for a small appliance) or twin and earth (flat stiff cable as used for lighting circuits)

 

[leevis]

Is most definitely flex and not twin and earth. How many cores are likely to be in there? 5?
These are going to be very thin, whats the best way to splice?

 

[JohnD]

let's see the size of it.

Look at your CH programmer and thermostat. Turn off the power at your main switch first. If you take the cover off you can look at the cable and see if it is the same.

Why do you need to splice it?

 

[leevis]

it somehow managed to slip under a joist whilst renovating a bathroom and the only way to fit it back up is to splice/cut/rejoin

 

[ban-all-sheds]

How many cores are likely to be in there?

The number you can see at the ends where the outer sheath is removed.

it somehow managed to slip under a joist whilst renovating a bathroom and the only way to fit it back up is to splice/cut/rejoin

1. Can't it stay where it is?

2. Is replacing it end-to-end not an option?

 

[leevis]

No It cant stay where it is because it will be caught inside the plasterboard and outside, hard to explain but cant stay where it is.
Cant replace it end to end unfortunately, cutting and rejoining is the only option. Normally I use Wago connectors to join but don't think these will fit those

 

[ban-all-sheds]

Will the joint be accessible?

 

[JohnD]

multicore CH control cable is quite fat.

Phone cable is quite thin.

 

[leevis]

I'll take a pic later on but the thickness from memory is about 5mm certainly nowhere near twin core and earth size, perhaps it is phone. If it is that would be dead handy