I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.

ss Wrote in message:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.


Switch power on at mains, test each wire.
--
Jim K


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

On Sat, 01 Jun 2019 23:49:31 +0100, Jim K.. wrote:

ss Wrote in message:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.


Switch power on at mains, test each wire.

Insufficient advice. Doesn't allow for eliminating false positives
("ghost voltages").



--
Leave first - THEN negotiate!

Cursitor Doom Wrote in message:
On Sat, 01 Jun 2019 23:49:31 +0100, Jim K.. wrote:

ss Wrote in message:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.


Switch power on at mains, test each wire.

Insufficient advice. Doesn't allow for eliminating false positives
("ghost voltages").




Follow given advice. Return if "ghost voltages" exist. FFS...
--
Jim K


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

Yes it was maybe something that they should have done before taking the old
unit out using a meter with a probe assuming of course te on situation is
controllable and is not some function of a thermostat, but then I think if
one is live and one not you have your answer if everything is cold at the
time.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Jim K.." wrote in message
o.uk...
ss Wrote in message:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.


Switch power on at mains, test each wire.
--
Jim K


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

On 02/06/2019 07:52, Brian Gaff wrote:
Yes it was maybe something that they should have done before taking the old
unit out using a meter with a probe assuming of course te on situation is
controllable and is not some function of a thermostat, but then I think if
one is live and one not you have your answer if everything is cold at the
time.
Brian

I agree however I did mark one of the reds so when I took the old fan
down I could then match it up with the identification markings on the
fan, only then did I discover the old fan is marked N and L but nothing
for the 3rd wire.
I did take a picture before disconnecting but that doesnt solve it due
to lack of identification markings.

On 01/06/2019 23:16, ss wrote:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.

Easy way - look at which is connected to the existing switched live
terminal on the fan, then mark it with tape before disconnecting. :-)


--
Cheers,

John.

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

On 01/06/2019 23:16, ss wrote:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.

I would be tempted to make a guess knowing there's a 50% likelihood of
it being right!

On 02/06/2019 02:21, Fredxx wrote:
On 01/06/2019 23:16, ss wrote:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what
one is live switch, how do I determine what one of the reds is live
switch, with the power switch off at mains.

I would be tempted to make a guess knowing there's a 50% likelihood of
it being right!

+1

Timer works, job done.
Timer does not work - then swap the reds over.

--
Adam

On 01/06/2019 23:16, ss wrote:
I am changing an extraction fan with timer.
The old fan has 2 red and a black wire but no indication as to what one
is live switch, how do I determine what one of the reds is live switch,
with the power switch off at mains.

Stick a bulb across, one of the lives and neutral. Then put the power
back on.

Either the bulb will be controlled by the light switch or not
(permanently on).

--
Adrian C

On 02/06/2019 08:54, Adrian Caspersz wrote:
Stick a bulb across, one of the lives and neutral. Then put the power
back on.

Either the bulb will be controlled by the light switch or not
(permanently on).

I assume using my cheap multimeter I could do the same and check for
voltage?

On 02/06/2019 09:02, ss wrote:
On 02/06/2019 08:54, Adrian Caspersz wrote:
Stick a bulb across, one of the lives and neutral. Then put the power
back on.

Either the bulb will be controlled by the light switch or not
(permanently on).

I assume using my cheap multimeter I could do the same and check for
voltage?

Yes. Look for changes when you 'modulate' the light switch.

--
Adrian C

On Sun, 02 Jun 2019 09:05:10 +0100, Adrian Caspersz wrote:

On 02/06/2019 09:02, ss wrote:
On 02/06/2019 08:54, Adrian Caspersz wrote:

I assume using my cheap multimeter I could do the same and check for
voltage?

Yes. Look for changes when you 'modulate' the light switch.

Yes, but not with a "cheap multimeter" - those ones typically pay zero
attention to proper mains isolation despite their self-declared CAT
ratings and have no MOVs etc.


--
Leave first - THEN negotiate!

Cursitor Doom Wrote in message:
On Sun, 02 Jun 2019 09:05:10 +0100, Adrian Caspersz wrote:

On 02/06/2019 09:02, ss wrote:
On 02/06/2019 08:54, Adrian Caspersz wrote:

I assume using my cheap multimeter I could do the same and check for
voltage?

Yes. Look for changes when you 'modulate' the light switch.

Yes, but not with a "cheap multimeter" - those ones typically pay zero
attention to proper mains isolation despite their self-declared CAT
ratings and have no MOVs etc.



How much should the op spend on a "proper multimeter" to do the
job properly?
--
Jim K


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

On 02/06/2019 10:47, Cursitor Doom wrote:
On Sun, 02 Jun 2019 09:05:10 +0100, Adrian Caspersz wrote:

On 02/06/2019 09:02, ss wrote:
On 02/06/2019 08:54, Adrian Caspersz wrote:

I assume using my cheap multimeter I could do the same and check for
voltage?

Yes. Look for changes when you 'modulate' the light switch.

Yes, but not with a "cheap multimeter" - those ones typically pay zero
attention to proper mains isolation despite their self-declared CAT
ratings and have no MOVs etc.

You don't touch any metal parts of a "cheap multimeter" as they are all
plastic apart from the metal parts of the probes.

--
Max Demian

On 02/06/2019 09:02, ss wrote:
On 02/06/2019 08:54, Adrian Caspersz wrote:
Stick a bulb across, one of the lives and neutral. Then put the power
back on.

Either the bulb will be controlled by the light switch or not
(permanently on).

I assume using my cheap multimeter I could do the same and check for
voltage?

Not too cheap, some don't really like mains even though they have a big
AC range.
They don't have enough insulation to be safe.
I certainly wouldn't use the £1.99 ones I bought on mains if I had to
touch them.

On 02/06/2019 11:26, dennis@home wrote:
I certainly wouldn't use the £1.99 ones I bought on mains if I had to
touch them.

Issue now sorted having identified the correct wires.