room thermostat

[Virtualcom13at]

Hi,

Question-A mains operated room thermostat requires three conductors to enable it to operate correctly. can you connect the thermostat to an existing two core and cpc cable and.

A=Use the earth
B=Use the earth and sheath with green and yellow
C=Use the earth sheath with brown
D=Not use at all

Im thinking you cant use the earth as your not allowed to use it as anything other than earth so that would rule out A + C. Does the Cpc cable count as one of the three conductors the thermostat needs to operate as its a bonding conductor ( I think ). or am i totally of the mark? I have only been studying for just over a month so be gentle.
Thanks

 

[truckster]

It depends on the roomstat, a basic bellows stat only needs a two core, live/switch live, an electronic stat needs the neutral to function and it also is used for a accelerator which stops the stat from switching on/off around the set mark.

The cpc is not required on many modern stats as the are class 2 but some still have a metal base and these need to be earthed. You can not use the cpc as a live or neutral conductor.

To sum up, if you have a twin in place use a standard bellows stat, if you are wiring new use a three core and earth to give max. flexibilty.

 

[Virtualcom13at]

It depends on the roomstat, a basic bellows stat only needs a two core, live/switch live, an electronic stat needs the neutral to function and it also is used for a accelerator which stops the stat from switching on/off around the set mark.

The cpc is not required on many modern stats as the are class 2 but some still have a metal base and these need to be earthed. You can not use the cpc as a live or neutral conductor.
To sum up, if you have a twin in place use a standard bellows stat, if you are wiring new use a three core and earth to give max. flexibilty.

But all we have is an existing two core and cpc cable. the thermostat in question requires 3 conductors. im confused! as i would say we cant use the existing cable as we cant use the cpc cable as a conductor but there is no option for this. unless thats what they mean by answer D.
hmmm have i just answered my question????

 

[telectrix]

yep, you just won the coconut. this happens frequently when someone wants to change a 2 wire stat for a 3 wire stat. can't be done without re-cabling in 3 core+E.

 

[Virtualcom13at]

yep, you just won the coconut. this happens frequently when someone wants to change a 2 wire stat for a 3 wire stat. can't be done without re-cabling in 3 core+E.

Happy days.
Cheers bud

By the way she always comes back out of tesco with the same baby because they never have what u want.:43:

 

[SyncroMan]

In the absence of any 3 core is it acceptable to run a second twin and earth and use one of the conductors, so long as the cpc's are connected?

 

[telectrix]

yes, as long as the new cable follows the same route.

 

[ringer]

Why does it have to follow the same route, tel?

 

[micknew]

Why not fit a wireless room stat?

 

[D80]

In the absence of any 3 core is it acceptable to run a second twin and earth and use one of the conductors, so long as the cpc's are connected?

Why not just pull in a PVC/PVC Single Cable if all you require is a 3rd core?

 

[SyncroMan]

Thanks for the replies.

I have to admid i'm probably being a bit tight not buying some 3 core or a wireless stat but ive got spare twin and earth and the wiring route is clear. I am just rewiring the house and that was one of the last jobs.

 

[Top Cat]

Why not just pull in a PVC/PVC Single Cable if all you require is a 3rd core?

I would say it would have to be 6241Y ie single core pvc/pvc + earth

 

[D80]

CPC would already be at stat and boiler/wiring centre from the Twin & Earth.

 

[grimysparks80]

The cpc is not required on many modern stats as the are class 2 but some still have a metal base and these need to be earthed. You can not use the cpc as a live or neutral conductor.

To sum up, if you have a twin in place use a standard bellows stat, if you are wiring new use a three core and earth to give max. flexibilty.

Shouldnt the cpc be continuous throught the circuit even if the room stat itself doesnt require one?

 

[Top Cat]

CPC would already be at stat and boiler/wiring centre from the Twin & Earth.

If you don't have an earth in the cable and it is buried in the wall someone could nail it and the nail would become live.