I'd like to wire the shower room extractor fan from the shower pull-switch so that it goes on with the shower and not the light. I found some info where one person said it's a no-no under current wiring regs but could be done via a contactor, and another says it can be done without a contactor as long as it goes via a fused spur from the shower switch.

Any electricians here can tell me which is the legal way to do it as I'd like to do it through a fused spur from the shower pull switch for simplicity..

Why do you use the shower isolator in normal use?

On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.

If you wanted to power and trigger the fan from the lighting circuit,
but also trigger it from the shower circuit, then you get into the
realms of needing contactors/relays etc to keep the circuits
electrically isolated from each other.


--
Cheers,

John.

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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 27/10/2020 17:12, Jimk wrote:
Jimk Wrote in message:
John Rumm Wrote in message:
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.


Could he wire it from the supply side of the shower switch & avoid
that?


The permanent live for overrun I mean...



or even wire the fan into the shower itself, so picking up the permanent
live before the controls and the switched live after the controls?

Thus removing the risk of confusion if wired into the the shower
isolation switch?

S.

John Rumm Wrote in message:
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.


Could he wire it from the supply side of the shower switch & avoid
that?

--
Jimk


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

Jimk Wrote in message:
John Rumm Wrote in message:
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.


Could he wire it from the supply side of the shower switch & avoid
that?


The permanent live for overrun I mean...
--
Jimk


----Android NewsGroup Reader----
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@John Rumm, not sure I understand what you're saying. What I intended was to run some three core and earth from the shower pull switch so that I'd have a permanent live and neutral and a switched live all going to the fan via a fused fan isolating switch. So the fan will still run on when the shower pull switch is turned off after using the shower. None of that would go near the consumer unit of course. Does that sound ok?

On 27/10/2020 14:57:12, me wrote:
I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity.

Most people would opt for a fan with a humidistat.

On 27/10/2020 17:30, me wrote:
@John Rumm, not sure I understand what you're saying. What I intended was to run some three core and earth from the shower pull switch so that I'd have a permanent live and neutral and a switched live all going to the fan via a fused fan isolating switch. So the fan will still run on when the shower pull switch is turned off after using the shower. None of that would go near the consumer unit of course. Does that sound ok?

It's how mine is wired here. Except to the light, and not the shower


--
€œThere are two ways to be fooled. One is to believe what isnt true; the
other is to refuse to believe what is true.€�

€”Soren Kierkegaard

Fredxx Wrote in message:
On 27/10/2020 14:57:12, me wrote:
I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity.

Most people would opt for a fan with a humidistat.




I wouldnt they fail all the time...
--
Jimk


----Android NewsGroup Reader----
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No Name Wrote in message:
On 27/10/2020 17:12, Jimk wrote:
Jimk Wrote in message:
John Rumm Wrote in message:
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.


Could he wire it from the supply side of the shower switch & avoid
that?


The permanent live for overrun I mean...



or even wire the fan into the shower itself, so picking up the permanent
live before the controls and the switched live after the controls?

Thus removing the risk of confusion if wired into the the shower
isolation switch?

S.


What "controls" are you talking about?
--
Jimk


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

The Natural Philosopher Wrote in message:
On 27/10/2020 17:30, me wrote:
@John Rumm, not sure I understand what you're saying. What I intended was to run some three core and earth from the shower pull switch so that I'd have a permanent live and neutral and a switched live all going to the fan via a fused fan isolating switch. So the fan will still run on when the shower pull switch is turned off after using the shower. None of that would go near the consumer unit of course. Does that sound ok?

It's how mine is wired here. Except to the light, and not the shower



Exactly what the op doesn't want then...
--
Jimk


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

On 27/10/2020 17:12, Jimk wrote:
Jimk Wrote in message:
John Rumm Wrote in message:
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.


Could he wire it from the supply side of the shower switch & avoid
that?


The permanent live for overrun I mean...

You could although you would need to fuse that as well, since many fan
manufacturers spec a 3A supply fuse.


--
Cheers,

John.

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

On 27/10/2020 17:30, me wrote:
@John Rumm, not sure I understand what you're saying. What I intended
was to run some three core and earth from the shower pull switch so
that I'd have a permanent live and neutral and a switched live all
going to the fan via a fused fan isolating switch. So the fan will
still run on when the shower pull switch is turned off after using
the shower. None of that would go near the consumer unit of course.
Does that sound ok?


Yup, that would be fine - your OP made it sound like you just wanted to
pickup just from the switched live from the shower isolator.

The only slight practical difficulty you may have is getting a good
termination on the smaller fan cable at the same time as the (sometimes
significantly) larger shower supply cable, bearing in mind shower
connections need to be 'kin tight!

You will also need to check that whatever cable you use to connect the
fan is offered adequate fault current protection by the shower MCB. This
is not likely to be a problem with say a B32 MCB and 1.5mm^2 3&E. But
you start getting more marginal on larger MCBs and shorter cable lengths
(as the prospective fault current rises). Having the fuse close to the
main shower isolator helps reduce the risks.


--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm Wrote in message:
On 27/10/2020 17:12, Jimk wrote:
Jimk Wrote in message:
John Rumm Wrote in message:
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.


Could he wire it from the supply side of the shower switch & avoid
that?


The permanent live for overrun I mean...

You could although you would need to fuse that as well, since many fan
manufacturers spec a 3A supply fuse.


Presumably it'll need fusing wherever it's fed from then?

What's the neatest way to do that?
--
Jimk


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

What about if I feed the permanent fan supply from a light fitting as normal with 1.5mm twin and earth cable and then run a 1mm twin and earth cable from the shower pull switch just for the switched live feed? That way the fan goes on with the shower pull switch but is not fed permanently by the shower circuit. Not sure where to fuse though if it is ok?

On 27/10/2020 20:15:09, me wrote:
What about if I feed the permanent fan supply from a light fitting as
normal with 1.5mm twin and earth cable and then run a 1mm twin and
earth cable from the shower pull switch just for the switched live
feed? That way the fan goes on with the shower pull switch but is not
fed permanently by the shower circuit. Not sure where to fuse though
if it is ok?

Your fan should not be fed from more than one circuit.

If you want it to come on when the shower is on, you would need a relay,
preferably a changeover one (SPDT) that won't put the bathroom light on
at the same time as the fan.

On 27/10/2020 14:57:12, me wrote:
I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity.

Have you considered of a PIR sensor to detect someone in the bathroom?
Might be additionally useful for when someone does a smelly No 2.

On 27/10/2020 20:15, me wrote:

What about if I feed the permanent fan supply from a light fitting as
normal with 1.5mm twin and earth cable and then run a 1mm twin and
earth cable from the shower pull switch just for the switched live
feed?

Really *really* bad idea - that would be powering one appliance from two
separate circuits (which might not even share a RCD!)

(not to mention feeding a lighting circuit wired in 1 or 1.5mm^2 T&E
from combined nominal current rating on a pair of MCBs that could be
over 50A)

That way the fan goes on with the shower pull switch but is not
fed permanently by the shower circuit. Not sure where to fuse though
if it is ok?

If you want to do something like that, then you would be better with an
arrangement like:

http://wiki.diyfaq.org.uk/index.php/...tivated_switch


--
Cheers,

John.

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

On 27/10/2020 20:59, Fredxx wrote:
On 27/10/2020 20:15:09, me wrote:
What about if I feed the permanent fan supply from a light fitting as
normal with 1.5mm twin and earth cable and then run a 1mm twin and
earth cable from the shower pull switch just for the switched live
feed? That way the fan goes on with the shower pull switch but is not
fed permanently by the shower circuit. Not sure where to fuse though
if it is ok?

Your fan should not be fed from more than one circuit.

If you want it to come on when the shower is on, you would need a relay,
preferably a changeover one (SPDT) that won't put the bathroom light on
at the same time as the fan.

Yup, played that game with a fan setup combining humidistat along with
delayed light activated operation with timed run on:

http://wiki.diyfaq.org.uk/index.php/...d_humidista t

(I had to use the second setup to prevent the humidistat turning on the
light!)


--
Cheers,

John.

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

On 27/10/2020 19:41, Jimk wrote:
John Rumm Wrote in message:
On 27/10/2020 17:12, Jimk wrote:
Jimk Wrote in message:
John Rumm Wrote in message:
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the
fan when you turn the switch off, you would lose any ability to have a
an automatically timed run on after the shower.


Could he wire it from the supply side of the shower switch & avoid
that?


The permanent live for overrun I mean...

You could although you would need to fuse that as well, since many fan
manufacturers spec a 3A supply fuse.


Presumably it'll need fusing wherever it's fed from then?

What's the neatest way to do that?

FCU connected to the permanent live on the lighting circuit, its output
feeding both the permanent live to the fan and the permanent live to the
light switch. That way the switched live return from the switch is also
appropriately fused.


--
Cheers,

John.

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

Many moons ago, I recall an extractor which had rechargeable batteries in a
little well quite big box which also had a mains to low voltage psu in it..
The idea was that the batteries kept the fan on for a few minutes after the
mains went off. I remember at the time thinking, this looks like a bit of a
problem when the batteries start to not hold a charge!

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.!
"John Rumm" wrote in message
o.uk...
On 27/10/2020 14:57, me wrote:

I'd like to wire the shower room extractor fan from the shower
pull-switch so that it goes on with the shower and not the light. I
found some info where one person said it's a no-no under current
wiring regs but could be done via a contactor, and another says it
can be done without a contactor as long as it goes via a fused spur
from the shower switch.

Any electricians here can tell me which is the legal way to do it as
I'd like to do it through a fused spur from the shower pull switch
for simplicity..

You can do it with a fused spur from the shower isolator switch it you
want. You should label it at the consumer unit to avoid surprises for
later maintainers. Also since you would be removing all power from the fan
when you turn the switch off, you would lose any ability to have a an
automatically timed run on after the shower.

If you wanted to power and trigger the fan from the lighting circuit, but
also trigger it from the shower circuit, then you get into the realms of
needing contactors/relays etc to keep the circuits electrically isolated
from each other.


--
Cheers,

John.

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

On Tuesday, 27 October 2020 at 22:55:26 UTC, John Rumm wrote:


http://wiki.diyfaq.org.uk/index.php/...d_humidista t


Yes that's how I'd like to do it but a home built one would not pass inspection. Is there a commercial version i can buy off the shelf?

On 28/10/2020 16:49, me wrote:
On Tuesday, 27 October 2020 at 22:55:26 UTC, John Rumm wrote:


http://wiki.diyfaq.org.uk/index.php/...d_humidista t



Yes that's how I'd like to do it but a home built one would not pass
inspection.

Inspection by who?

I would have thought that by its very nature, most relay switching and
transient suppression is going to be built up for a special purpose and
hence "home built" in pretty much any case.

Is there a commercial version i can buy off the shelf?

The fan I used and the humidistat were standard off the shelf parts -
but separate.

There are versions that combine timer operation with humidistat if you
want as well:

https://www.tlc-direct.co.uk/Products/ADQT120HT.html

(although quite a bit more pricey).

Part of the attraction of having the functions separated is that you can
place the humidistat in a place where its easy to access and tweak the
settings, without needing to get into the fan itself.

Note that many fans with integrated electronics will specify that
transient suppression be installed to protect them if the circuit also
contains a number of other potential sources of mains transient
including SMPSUs, Dimmers, Florescent lights etc.

For example on the one above:

"EMV regulation
Important indication for the electromagnetic compatibility

Interference resistance according to DIN EN 55014-2 depending upon
impulse form and energy rate of 1000 V to 4000 V. With operation with
fluorescent tubes, switch power supplies, electronically regulated
halogen bulbs etc. these values can be exceeded. In this case
additional suppression shielding activities are necessary (L -, C or RC
elements, protection diodes, resistors)."




--
Cheers,

John.

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

On Wednesday, 28 October 2020 at 17:12:21 UTC, John Rumm wrote:
On 28/10/2020 16:49, me wrote:
On Tuesday, 27 October 2020 at 22:55:26 UTC, John Rumm wrote:


http://wiki.diyfaq.org.uk/index.php/...d_humidista t



Yes that's how I'd like to do it but a home built one would not pass
inspection.
Inspection by who?

I would have thought that by its very nature, most relay switching and
transient suppression is going to be built up for a special purpose and
hence "home built" in pretty much any case.
Is there a commercial version i can buy off the shelf?
The fan I used and the humidistat were standard off the shelf parts -
but separate.

There are versions that combine timer operation with humidistat if you
want as well:

https://www.tlc-direct.co.uk/Products/ADQT120HT.html

(although quite a bit more pricey).

Part of the attraction of having the functions separated is that you can
place the humidistat in a place where its easy to access and tweak the
settings, without needing to get into the fan itself.

Note that many fans with integrated electronics will specify that
transient suppression be installed to protect them if the circuit also
contains a number of other potential sources of mains transient
including SMPSUs, Dimmers, Florescent lights etc.

For example on the one above:

"EMV regulation
Important indication for the electromagnetic compatibility

Interference resistance according to DIN EN 55014-2 depending upon
impulse form and energy rate of 1000 V to 4000 V. With operation with
fluorescent tubes, switch power supplies, electronically regulated
halogen bulbs etc. these values can be exceeded. In this case
additional suppression shielding activities are necessary (L -, C or RC
elements, protection diodes, resistors)."
--
Cheers,

John.

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


John thanks for the reply. I referenced the wrong thing, I meant the self-build current sensing switch you posted a link to. I could build one of those but as I say, inspection by the local council spark almost certainly won't pass because it obviously will have no industry standard test marks. So I found exactly the type of thing I would like on Amazon he https://www.amazon.co.uk/Precision-S...strial&sr=1-18
Now that is a Chinese made one so again I doubt it'd pass inspection, so my question was is there a UK made device such as that one?

On 29/10/2020 11:39, me wrote:
On Wednesday, 28 October 2020 at 17:12:21 UTC, John Rumm wrote:
On 28/10/2020 16:49, me wrote:
On Tuesday, 27 October 2020 at 22:55:26 UTC, John Rumm wrote:


http://wiki.diyfaq.org.uk/index.php/...d_humidista t





Yes that's how I'd like to do it but a home built one would not pass
inspection.
Inspection by who?

I would have thought that by its very nature, most relay switching
and transient suppression is going to be built up for a special
purpose and hence "home built" in pretty much any case.
Is there a commercial version i can buy off the shelf?
The fan I used and the humidistat were standard off the shelf parts
- but separate.

There are versions that combine timer operation with humidistat if
you want as well:

https://www.tlc-direct.co.uk/Products/ADQT120HT.html

(although quite a bit more pricey).

John thanks for the reply. I referenced the wrong thing, I meant the
self-build current sensing switch you posted a link to.

ah, ok sorry talking at cross purposes.

I could build
one of those but as I say, inspection by the local council spark
almost certainly won't pass because it obviously will have no
industry standard test marks. So I found exactly the type of thing I
would like on Amazon he
https://www.amazon.co.uk/Precision-S...strial&sr=1-18

Its relatively easy to find current sensing extension leads with slaved
sockets. So it turns off the other sockets when you stop drawing power
through a sense socket.

Needless to say not much use for a shower.

For that something like:

https://www.eaton.com/us/en-us/catal...t-sensors.html

Would be more appropriate

--
Cheers,

John.

/================================================== ===============\
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