Girly question from a newbie!

[amytomsam]

I am a girly DIYer...I am going to replace my Honeywell T40 room thermostat in the hall with a Siemens REV11.
This is a wiring question which is products specific. I have to gather information but haven't found the exact 2 products to cross reference....
On the T40 the wires coming from the wall are wired as follows.
On the wall plate of the T40 there are 5 possible connectors.
In sequence it is wired up as follows, from left to right.
Earth to earth. (green and yellow wire)
Blue wire to connector 2
yellow wire to connector 3
Connector 4 is vacant (unwired)
red wire to connector 1

I have a new Siemens Rev11
It has two terminals for connection.
L and L1

I have ascertained that I don't need to earth it as it has a plastic back plate so that's that wire dealt with!
I suspect that the red (t40) wire goes to the new (siemens) L but not sure about the blue and yellow wires.

Am I right in suspecting the blue (T40) wire goes to the new (siemens) L1 and that I insulate the yellow??????

Help.....

 

[gas4you]

I would assume the blue is neutral and therefore should be made safe and not used unless the REV11 asks for a neutral.

The red and yellow wires will be the switched live in and out and these should be connected to L & L1.

If the REV11 is battery operated then you will definately not need the neutral.

 

[amytomsam]

REV11 is battery operated and so that's the blue sorted then..will make safe.
Earth not needed as plastic...will make safe (tape up)

Just to confirm....red to L
Yellow to L1

THX

 

[gas4you]

Sounds ok from here, but I have to assume they have correctly used blue as the neutral

 

[amytomsam]

What will happen if they haven't?...
How can I tell/be sure?

 

[seco services]

use a multi meter

 

[amytomsam]

Ta for that then.....

 

[amytomsam]

OK....I do have one of those multi meters...my dad bought it for me, I would have preferred chocolates but hey!...anyway, I can test batteries with it but not sure on the whole electics and circuits bit of testing stuff. Sorry....not entirely knowledgeable...he did show me how to use it but wasn't paying too much attention and it was ages ago. I'm not really going to blow stuff up am I??

 

[seco services]

only yourself if its live.
ask your dad if he knows to test it for you.
or follow the blue back see if it joins the neutrals

 

[mogget]

I agree with seco that the easiest way is probably to have a look at the other end of the cable!

 

[amytomsam]

ok.....I have multi meter tested it....I have 240V on the red so that is definately live! but no readings on either the blue or yellow....
I suppose I could chocolate block the yellow and red together and see if it turns the heating on to check if it is the right one?? bu5t is there any other way I can check if I need to wire they yellow or blue???
WITHOUT having to track back wires which I have no chance of being able to do?

 

[amytomsam]

The cables all disappear into the wall and go upstairs into the airing cupboard to the main heating control timer thingy....I've got no chance of tracking them back!

 

[seco services]

you have if you follow a drawing system wiring ie y, s plan etc.

 

[amytomsam]

Hmmm I have a Y plan that came with the heating and it details connections to the Honeywell junction box in the airing cupbard. The blue is neutral on this...hopefully that means that we have resolved that question and things won't get blowy uppy.....

 

[seco services]

thats what where saying just cause its blue on the drawing don't mean the installer used the right colours.

don't take it for granted it makes a nasty mess of your screwdrivers if its live.