What circuit should a room thermostat be on in a house?

[philiusfog]

Hi,

We live in a house built post 2005 and I'm looking to replace my room thermostat.

I have the following circuits:

Water heater,
Downstairs lighting,
Upstairs lighting,
Sockets,
Cooker.

Which wone should the thermostat (its in the downstairs living room) be on, in good working practice, so that I can disconnect and replace with a new digital thermostat?

The room is very dark naturally and i need to have the lights (ideally - rather not use a torch) to be able to see wiring and replace.

Any help, will be much appreciated.

 

[RMS]

Do yourself a favour and switch off the main switch.

Even if I was to assume a circuit, how would you confirm the cabling is dead?

 

[DetlefSchmitz]

Slightly puzzling question as it is already on some circuit or other, and if you don't know how to find out, then maybe you should be getting someone else to do the work.

Let's assume you have a boiler providing your house heating. This should have a fused connection unit next to it and this should also be the FCU which isolates the thermostat, as the heating circuitry should all be isolated from a single point. So if the boiler goes off when you switch on the circuit breaker on the 'sockets', for example, then turning off that breaker would also be a good idea. (It won't be on the lighting circuit.)

However you would then have to check that the thermostat wiring really was isolated, before it was safe to work on it.

Before disconnecting the old thermostat or buying a new one, you need to find out if the new thermostat is compatible with the existing wiring. The new one may require a neutral and you may not have one.

 

[LearningSpark]

I would put the thermostat on the cooker circuit then you will be able to regulate the room and the cooker temperature at the same time.

 

[ricicle]

It will most probably be off the socket circuit but I would switch everything off apart from the lights and double check by firing the boiler up, clicking stat up to max and then turning off at the CU and listening for the boiler/pump to shut down. (In the absence of proper test equipment)

 

[JonB]

L----Spark
I see we have another really helpful sarcastic twot on the forum.

 

[onlyfitidealboilers]

I would put the thermostat on the cooker circuit then you will be able to regulate the room and the cooker temperature at the same time.

WTF

Find the fused spur for your central heating and switch it off. have you a combi boiler???

 

[ericmark]

Never assume. I was asked to move a socket. House not moved into so easy turn off main isolator. However when I set to work, fortunately using a neon screwdriver it lit. Found supplied from next door. It was good lesson I now always test for dead.

Although one would assume given the options it would be supplied from the sockets supply one has no way to be sure. And it could be feed from lights, just because it shouldn't be feed from lights is no guarantee that it will not be.

Of course neutral is a live cable and the MCB will only isolate the line. So one should not isolate with a MCB. The fused connection unit is likely designed so on drawing the fuse a lock can be put in the fuse holder to prevent it being re-energised. However proving dead is the first step in any electrical work and if you can't do that then don't do the work.

 

[onlyfitidealboilers]

v good advice eric

 

[mcluma]

I got this one for free, and i use it now all the time, like said before, testing is beter then assuming

 

[ban-all-sheds]

I got this one for free

And it's worth every penny you paid for it.

Get a proper tester.

 

[bernardgreen]

I got this one for free, and i use it now all the time, like said before, testing is beter then assuming

Was it the local undertaker handing them out to increase business ?

All single point of contact testers rely on a capacity connected route to ground via the person holding the tester. In many situations that route isn't there.

You can only get a reliable test by using a two point of contact tester and a known good zero potential reference point.