I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Maxwell Boltzmann wrote:

I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

With all the electricy off at the MCBs, but on at the main switch, find
which wire is less than a couple of ohms to neutral in any handy socket.
(Possibly one of the others will only be few tens or hundreds of ohms if
there is something inductive connected, but ignore this.) That wire is
probably neutral. With the electricity on check which wire is live.
That is the live wire. The third wire is switched live.


Alternatively, look at the other end and note the colour code.

--

Roger Hayter

On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral & switched live: with power off N has near zero resistance to neutral, swL will have much more R.


NT

posted
On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral &
switched live: with power off N has near zero resistance to neutral,
swL will have much more R.


Thanks to you and Roger. One of the problems is that there *is* no handy
socket nearby to which I can measure the voltage/resistance to earth and
live; but no doubt I can get round that.

--
Max
MD5[file 0279.jpg] = 756EEDE2CAE88D9D51AD05F96C0EB09B

"Maxwell Boltzmann" wrote in message
...
posted
On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral &
switched live: with power off N has near zero resistance to neutral, swL
will have much more R.


Thanks to you and Roger. One of the problems is that there *is* no handy
socket nearby to which I can measure the voltage/resistance to earth and
live; but no doubt I can get round that.

Yep, just run an extension cord to any socket you like.

Maxwell Boltzmann wrote:

posted
On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral &
switched live: with power off N has near zero resistance to neutral,
swL will have much more R.


Thanks to you and Roger. One of the problems is that there *is* no handy
socket nearby to which I can measure the voltage/resistance to earth and
live; but no doubt I can get round that.

Neutral, not earth for the resistance measurement. They may not be
sufficiently similar if you don't have the right sort of house earthing.

--

Roger Hayter

On 15/10/2017 14:25, Maxwell Boltzmann wrote:
posted
On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral &
switched live: with power off N has near zero resistance to neutral,
swL will have much more R.


Thanks to you and Roger. One of the problems is that there *is* no handy
socket nearby to which I can measure the voltage/resistance to earth and
live; but no doubt I can get round that.

Extension lead may be your friend then...




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sunday, 15 October 2017 14:26:15 UTC+1, Maxwell Boltzmann wrote:
tabbypurr posted
On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:

I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral &
switched live: with power off N has near zero resistance to neutral,
swL will have much more R.


Thanks to you and Roger. One of the problems is that there *is* no handy
socket nearby to which I can measure the voltage/resistance to earth and
live; but no doubt I can get round that.

socket, metal light fitting, radiator, water tap or drain, most of those are earthed, but not all. The other option to identify live is to measure the 3 voltages between the 3 wires, live to N and live to swL will both give 240v, N to swL should give 0v. (Y plans do complicate this.)

Obviously safe practice is required.


NT

On 15/10/2017 09:40, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existingÂ* thermostat. So it is not immediately obvious which wire is which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Finding the other end of the cable and finding out what is connected to
what.


--
Michael Chare

wrote:

On Sunday, 15 October 2017 14:26:15 UTC+1, Maxwell Boltzmann wrote:
tabbypurr posted
On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:

I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral &
switched live: with power off N has near zero resistance to neutral,
swL will have much more R.


Thanks to you and Roger. One of the problems is that there *is* no handy
socket nearby to which I can measure the voltage/resistance to earth and
live; but no doubt I can get round that.

socket, metal light fitting, radiator, water tap or drain, most of those
are earthed, but not all. The other option to identify live is to measure
the 3 voltages between the 3 wires, live to N and live to swL will both
give 240v, N to swL should give 0v. (Y plans do complicate this.)

Obviously safe practice is required.


NT
Live to swL can give you Ov either because it is open circuit or because
(as you say) some other control has connected ti to live. If N to L and
N to swL are both 240v then further measures are necessary. Probably,
as you say, something to do with motorised valves and their switches.

If N to swL is Ov, which is which, if live to either gives 240V? I
think your scheme only works if you know exactly what is connected at
the other end and even then ambiguities are left.

Another possibility if you use a high impedance meter and swL is open
circuit is that N to swL will give you 5 or 10V AC. What do you
conclude from this?




--

Roger Hayter

On Monday, 16 October 2017 00:10:25 UTC+1, Roger Hayter wrote:
tabbypurr wrote:
On Sunday, 15 October 2017 14:26:15 UTC+1, Maxwell Boltzmann wrote:
tabbypurr posted
On Sunday, 15 October 2017 09:44:49 UTC+1, Maxwell Boltzmann wrote:

I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existing thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Live is easy to identify, it's 240v to the nearest earth. Neutral &
switched live: with power off N has near zero resistance to neutral,
swL will have much more R.


Thanks to you and Roger. One of the problems is that there *is* no handy
socket nearby to which I can measure the voltage/resistance to earth and
live; but no doubt I can get round that.

socket, metal light fitting, radiator, water tap or drain, most of those
are earthed, but not all. The other option to identify live is to measure
the 3 voltages between the 3 wires, live to N and live to swL will both
give 240v, N to swL should give 0v. (Y plans do complicate this.)

Obviously safe practice is required.

Live to swL can give you Ov either because it is open circuit

if so the system is broken

or because
(as you say) some other control has connected ti to live.

is it too hard to switch the programmer to off?

If N to L and
N to swL are both 240v then further measures are necessary.

but they aren't

Probably,
as you say, something to do with motorised valves and their switches.

If N to swL is Ov, which is which, if live to either gives 240V? I
think your scheme only works if you know exactly what is connected at
the other end and even then ambiguities are left.

I'm pretty sure I addressed that question

Another possibility if you use a high impedance meter and swL is open
circuit is that N to swL will give you 5 or 10V AC. What do you
conclude from this?

3 readings are required to reach any conclusions, not 1. Enjoy trolling.


NT

On 15/10/2017 23:49, Michael Chare wrote:
On 15/10/2017 09:40, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is already
an old three-wire connection for a (mechanical) thermostat, but no
existingÂ* thermostat. So it is not immediately obvious which wire is
which.

There is no earth connection. Using a multimeter, what is the simplest
and safest way of identifying each wire?

Max

Finding the other end of the cable and finding out what is connected to
what.


That's called stating the bleeding obvious:-).

Although I would want to know why there is no earth connection.


--
Adam

ARW wrote:

Michael Chare wrote:

Finding the other end of the cable and finding out what is
connected to what.

That's called stating the bleeding obvious:-).
Although I would want to know why there is no earth connection.

It's been 'promoted' to switched live for maximum surprise?

ARW posted
On 15/10/2017 23:49, Michael Chare wrote:
On 15/10/2017 09:40, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is
already an old three-wire connection for a (mechanical) thermostat,
but no existing* thermostat. So it is not immediately obvious which
wire is which.

There is no earth connection. Using a multimeter, what is the
simplest and safest way of identifying each wire?

Max
Finding the other end of the cable and finding out what is connected
to what.


That's called stating the bleeding obvious:-).

Although I would want to know why there is no earth connection.


Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

--
Jack

On 16/10/2017 22:02, Andy Burns wrote:
ARW wrote:

Michael Chare wrote:

Finding the other end of the cable and finding out what is
connected to what.

That's called stating the bleeding obvious:-).
Although I would want to know why there is no earth connection.

It's been 'promoted' to switched live for maximum surprise?



vbg


The further question also needs to be asked.

Does the boiler actually work without the missing roomstat?







--
Adam

Maxwell Boltzmann wrote:

ARW posted
On 15/10/2017 23:49, Michael Chare wrote:
On 15/10/2017 09:40, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is
already an old three-wire connection for a (mechanical) thermostat,
but no existing thermostat. So it is not immediately obvious which
wire is which.

There is no earth connection. Using a multimeter, what is the
simplest and safest way of identifying each wire?

Max
Finding the other end of the cable and finding out what is connected
to what.


That's called stating the bleeding obvious:-).

Although I would want to know why there is no earth connection.


Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe it
is considered good practice to install one.


Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

Any chance of hosting a scan somewhere? That seems a bit surprising for
something on sale in the UK.

--

Roger Hayter

On 16/10/2017 22:34, Maxwell Boltzmann wrote:
ARW posted
On 15/10/2017 23:49, Michael Chare wrote:
On 15/10/2017 09:40, Maxwell Boltzmann wrote:
I have to fit a room thermostat into a building where there is
alreadyÂ* an old three-wire connection for a (mechanical) thermostat,
but noÂ* existingÂ* thermostat. So it is not immediately obvious which
wire isÂ* which.

There is no earth connection. Using a multimeter, what is the
simplestÂ* and safest way of identifying each wire?

Max
Â*Finding the other end of the cable and finding out what is connected
toÂ* what.


That's called stating the bleeding obvious:-).

Although I would want to know why there is no earth connection.


Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.


I think you might be "reading" the diagram incorrectly fella.

Your diagram should look something like this

http://www.montel-css.co.uk/SupOther...llt6360wi.jpeg

possibly without the earth terminal shown. There would or should be an
earth cable there even if the stat does not require one.


--
Adam

Roger Hayter posted
Maxwell Boltzmann wrote:
Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe it
is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.



Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

Any chance of hosting a scan somewhere? That seems a bit surprising for
something on sale in the UK.


It's a Honeywell and the wiring diagram essentially the same as the one
ARW has just posted, but without the earth. It has an unused pin 5 so I
guess one could that for the earth.

I'm not sure what ARW means by me misunderstanding the diagram. The
connection to pin 3 is clearly a switched neutral (switched through the
load). There is no switched live feed to the thermostat.

--
Jack

Maxwell Boltzmann wrote:

I'm not sure what ARW means by me misunderstanding the diagram.

I'd say he's right :-P

The connection to pin 3 is clearly a switched neutral (switched
through the load). There is no switched live feed to the thermostat.
No, the neutral is permanently connected to the heating system (and the
anticipator) with the permanent live Pin1 switched to Pin2 when heating
is on.

Maxwell Boltzmann wrote:

Roger Hayter posted
Maxwell Boltzmann wrote:
Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe it
is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.



Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

Any chance of hosting a scan somewhere? That seems a bit surprising for
something on sale in the UK.


It's a Honeywell and the wiring diagram essentially the same as the one
ARW has just posted, but without the earth. It has an unused pin 5 so I
guess one could that for the earth.

I'm not sure what ARW means by me misunderstanding the diagram. The
connection to pin 3 is clearly a switched neutral (switched through the
load). There is no switched live feed to the thermostat.

I agree the diagram looks grossly misleading. But we must assume that
the wire marked 'live' is indeed a direct connection to live. The
yellow wire to terminal three does not connect to anything else in the
thermostat box (although terminal three also connects to one end of the
heater in the thermostat which heats the bimetal strip and is used to
reduce hysteriesis), but wanders off down the cable to the boiler
controls, described hear as 'heating system'. When the thermostat is
demanding heat the switch from terminal one connects to the contact on
terminal three and supplies live voltage to the boiler control. The
boiler control certainly will have its own neutral, but this is
connected directly at the boiler end and does not rely on the neutral
wire in the thermostat. Although electrically the boiler control
neutral is connected to the terminal two neutral at the boiler end,
there is no wire doing this connecting in the thermostat box despite the
junction shown, and just one neutral wire comes to the thermostat purely
for the purpose of supplying a current return for the anti-hysteresis
heater (called anticipator in the diagram).


If you imagine the orange 'heating system' box dragged off the page,
still connnected to its blue and yellow wires, and down the corridor and
connected by a yellow blue and red ( and also earth!) cable to the
thermostat then things fall into place. In theory the red and earth
cable do not need to come from the boiler control, as they are just live
and earth, but in practice this is the correct way to wire it. The live
incoming to the thermostat is connected to the switched live yellow wire
and activates the boiler control.


--

Roger Hayter

On 17/10/2017 19:33, Maxwell Boltzmann wrote:
Roger Hayter posted
Maxwell Boltzmann wrote:
Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe it
is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.

Not a problem if it's a class II appliance.



--
Adam

On 17/10/2017 20:04, Roger Hayter wrote:

If you imagine the orange 'heating system' box dragged off the page,
still connnected to its blue and yellow wires, and down the corridor and
connected by a yellow blue and red ( and also earth!) cable to the
thermostat then things fall into place.

I like that.



--
Adam

In article ,
Maxwell Boltzmann wrote:
Roger Hayter posted
Maxwell Boltzmann wrote:
Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe it
is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.



Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

Any chance of hosting a scan somewhere? That seems a bit surprising for
something on sale in the UK.


It's a Honeywell and the wiring diagram essentially the same as the one
ARW has just posted, but without the earth. It has an unused pin 5 so I
guess one could that for the earth.

I'm not sure what ARW means by me misunderstanding the diagram. The
connection to pin 3 is clearly a switched neutral (switched through the
load). There is no switched live feed to the thermostat.

There should be a switched live to the thermostat, It's the thermostat
that does the switching and it gives a switched live on pin 3. Pin 2 is
the neutral INPUT going to the heater element which gets its live from pin
3. If you can't read a very simple circuit diagram, should you be doing
this work yourself?

--
from KT24 in Surrey, England

In article , charles
wrote:
In article , Maxwell Boltzmann
wrote:
Roger Hayter posted
Maxwell Boltzmann wrote:
Aren't most thermostats made of plastic with no accessible metal
parts? The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe
it is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.



Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

Any chance of hosting a scan somewhere? That seems a bit surprising
for something on sale in the UK.


It's a Honeywell and the wiring diagram essentially the same as the one
ARW has just posted, but without the earth. It has an unused pin 5 so
I guess one could that for the earth.

I'm not sure what ARW means by me misunderstanding the diagram. The
connection to pin 3 is clearly a switched neutral (switched through the
load). There is no switched live feed to the thermostat.

CORRECTION

There should NOT be a switched live to the thermostat, It's the thermostat
that does the switching and it gives a switched live on pin 3.
Pin 2 is the neutral INPUT going to the heater element which gets its
live from pin 3.

If you can't read a very simple circuit diagram, should you be doing this
work yourself?

--
from KT24 in Surrey, England

charles Wrote in message:
In article , charles
wrote:
In article , Maxwell Boltzmann
wrote:
Roger Hayter posted
Maxwell Boltzmann wrote:
Aren't most thermostats made of plastic with no accessible metal
parts? The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe
it is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.



Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

Any chance of hosting a scan somewhere? That seems a bit surprising
for something on sale in the UK.


It's a Honeywell and the wiring diagram essentially the same as the one
ARW has just posted, but without the earth. It has an unused pin 5 so
I guess one could that for the earth.

I'm not sure what ARW means by me misunderstanding the diagram. The
connection to pin 3 is clearly a switched neutral (switched through the
load). There is no switched live feed to the thermostat.

CORRECTION

There should NOT be a switched live to the thermostat, It's the thermostat
that does the switching and it gives a switched live on pin 3.
Pin 2 is the neutral INPUT going to the heater element which gets its
live from pin 3.

If you can't read a very simple circuit diagram, should you be doing this
work yourself?



If you can't read a very simple circuit diagram, should you be
proffering "advice"?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Andy Burns posted
Maxwell Boltzmann wrote:

I'm not sure what ARW means by me misunderstanding the diagram.

I'd say he's right :-P

OK, then. In the diagram, the wires coming out of the wall are
represented by the coloured lines. Which is the switched live?


The connection to pin 3 is clearly a switched neutral (switched
through the load). There is no switched live feed to the thermostat.
No, the neutral is permanently connected to the heating system

Which is switched.

(and the anticipator) with the permanent live Pin1 switched to Pin2
when heating is on.

You don't say.

--
Max

Maxwell Boltzmann wrote:

Andy Burns posted:

Maxwell Boltzmann wrote:

I'm not sure what ARW means by me misunderstanding the diagram.

I'd say he's right :-P

OK, then. In the diagram, the wires coming out of the wall are
represented by the coloured lines. Which is the switched live?

In the diagram Adam supplied - the yellow wire is switched live.

On 17/10/2017 22:38, charles wrote:


If you can't read a very simple circuit diagram, should you be doing this
work yourself?

Everyone started off a virgin!

And the fact the OP had the nous to ask before making the connections is
a better start than some.




--
Robin
reply-to address is (intended to be) valid

In article ,
Maxwell Boltzmann wrote:
Andy Burns posted
Maxwell Boltzmann wrote:

I'm not sure what ARW means by me misunderstanding the diagram.

I'd say he's right :-P

OK, then. In the diagram, the wires coming out of the wall are
represented by the coloured lines. Which is the switched live?


The connection to pin 3 is clearly a switched neutral (switched
through the load). There is no switched live feed to the thermostat.
No, the neutral is permanently connected to the heating system

Which is switched.

No it isn't. The switch in question feeds the outgoing switched live and
also live to the other end of the heater (represented by a zigzag line).

(and the anticipator) with the permanent live Pin1 switched to Pin2
when heating is on.

You don't say.

--
from KT24 in Surrey, England

In article , Robin
wrote:
On 17/10/2017 22:38, charles wrote:


If you can't read a very simple circuit diagram, should you be doing
this work yourself?

Everyone started off a virgin!

And the fact the OP had the nous to ask before making the connections is
a better start than some.


True. But he seems to keep insisting on "switched neutral" - evena fter he
is ntold it isn't switched.

But it reminds me of a letter the BBC once reeceived " I think there should
be a book written about how Ceefax works. Please tell me so that I can
write the book."

--
from KT24 in Surrey, England

On 18/10/2017 11:09, Andy Burns wrote:
Maxwell Boltzmann wrote:

Andy Burns posted:

Maxwell Boltzmann wrote:

I'm not sure what ARW means by me misunderstanding the diagram.

I'd say he's right :-P

OK, then. In the diagram, the wires coming out of the wall are
represented by the coloured lines. Which is the switched live?

In the diagram Adam supplied - the yellow wire is switched live.

Do you think that there might be a misunderstanding here and that he is
talking about the live *TO* the thermostat being switched by a timer?

SteveW

Andy Burns posted
Maxwell Boltzmann wrote:

Andy Burns posted:

Maxwell Boltzmann wrote:

I'm not sure what ARW means by me misunderstanding the diagram.

I'd say he's right :-P
OK, then. In the diagram, the wires coming out of the wall are
represented by the coloured lines. Which is the switched live?

In the diagram Adam supplied - the yellow wire is switched live.


There is no thermostat. Where is the switched live?

--
Max

Maxwell Boltzmann wrote:

Andy Burns posted

Maxwell Boltzmann wrote:

Which is the switched live?

In the diagram Adam supplied - the yellow wire is switched live.

There is no thermostat.

What do you think a Honeywell T 6303 is?

Where is the switched live?

At this point I'm going to slow back away and leave you to it ...

In article ,
Andy Burns wrote:
Maxwell Boltzmann wrote:

Andy Burns posted

Maxwell Boltzmann wrote:

Which is the switched live?

In the diagram Adam supplied - the yellow wire is switched live.

There is no thermostat.

What do you think a Honeywell T 6303 is?

Where is the switched live?

At this point I'm going to slow back away and leave you to it ...

+1

--
from KT24 in Surrey, England

On 17/10/2017 19:33, Maxwell Boltzmann wrote:
Roger Hayter posted
Maxwell Boltzmann wrote:
Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe it
is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.

If its marked with a double insulated logo (square within a square) then
it does not mater if it is made of metal.

Incidentally, the wiring diagram printed inside the new thermostat
doesn't show a switched live connection but a switched neutral.

Any chance of hosting a scan somewhere? That seems a bit surprising for
something on sale in the UK.


It's a Honeywell and the wiring diagram essentially the same as the one
ARW has just posted, but without the earth. It has an unused pin 5 so I
guess one could that for the earth.

What model number?

I'm not sure what ARW means by me misunderstanding the diagram. The
connection to pin 3 is clearly a switched neutral (switched through the
load). There is no switched live feed to the thermostat.

Are you sure its not just a set of "no volt" contacts? (i.e. a switch
that closes, but is not connected to either live or neutral itself).


--
Cheers,

John.

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On 17/10/2017 22:38, charles wrote:

There should NOT be a switched live to the thermostat,

How would you describe the CH on connection from a programmer then?

e.g. pin 4 on the junction strip:

http://wiki.diyfaq.org.uk/images/6/6c/C-Plan-Wiring.gif


--
Cheers,

John.

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On Thursday, 19 October 2017 16:07:56 UTC+1, John Rumm wrote:
On 17/10/2017 19:33, Maxwell Boltzmann wrote:
Roger Hayter posted
Maxwell Boltzmann wrote:

Aren't most thermostats made of plastic with no accessible metal parts?
The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I believe it
is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I was
rather horrified the other day to find that my 3kW convection heater
(the kind you mount on the wall) had no earth wire, even though it's
made entirely of metal. It's one of the leading brands.

If its marked with a double insulated logo (square within a square) then
it does not mater if it is made of metal.

Years ago I saw some of those marked [[]] but in reality they did not take the relevant precaustions and the live connection was very close to the metal case. I don't remember the brand.


NT

On 19/10/2017 18:10, wrote:
On Thursday, 19 October 2017 16:07:56 UTC+1, John Rumm wrote:
On 17/10/2017 19:33, Maxwell Boltzmann wrote:
Roger Hayter posted
Maxwell Boltzmann wrote:

Aren't most thermostats made of plastic with no accessible
metal parts? The one I'm proposing to install certainly is.

There are advantages in having an earth wire available and I
believe it is considered good practice to install one.

No doubt, but lots of appliances are supplied without an earth. I
was rather horrified the other day to find that my 3kW convection
heater (the kind you mount on the wall) had no earth wire, even
though it's made entirely of metal. It's one of the leading
brands.

If its marked with a double insulated logo (square within a square)
then it does not mater if it is made of metal.

Years ago I saw some of those marked [[]] but in reality they did not
take the relevant precaustions and the live connection was very close
to the metal case. I don't remember the brand.

In much the same vein, you can get lots of LED lamps from China that
"must be earthed" and provide a wire for you to do so. Only problem is
there is no continuity between said wire and the metal case.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

In much the same vein, you can get lots of LED lamps from China that
"must be earthed" and provide a wire for you to do so. Only problem is
there is no continuity between said wire and the metal case.
My cheap chinese "20" watt LED floodlamp was like that, but it's died
now. I have an iSpot 30W to replace it with, it is surprisingly large
and basically all heatsink ... not fitted yet.

https://screwfix.com/p/ispot-30w-LED/5514h

On 18/10/2017 17:04, Maxwell Boltzmann wrote:
Andy Burns posted
Maxwell Boltzmann wrote:

Andy Burns posted:

Maxwell Boltzmann wrote:

I'm not sure what ARW means by me misunderstanding the diagram.

I'd say he's right :-P
Â*OK, then. In the diagram, the wires coming out of the wall are
represented by the coloured lines. Which is the switched live?

In the diagram Adam supplied - the yellow wire is switched live.


There is no thermostat. Where is the switched live?


Which comes back to the question I asked earlier that everyone missed.

Does the boiler actually work without the missing roomstat?


It makes a massive difference to how you do the job.


--
Adam