In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.
--
bert

On 28/02/2019 12:21, bert wrote:
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Possibly a suppressor in the motor has failed and the resulting
inductive spike is coupling into an adjacent circuit. Makes sense as
you say it doesn't always happen, probably only when the voltage happens
to be on a high part of the AC cycle.

Cheers
--
Clive

"Tim+" wrote in message
...
bert Wrote in message:
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.In the past few nights a
couple of times when switching it off the RCD protecting the ring mains
has tripped. But the lighting circuits don't go through it and the lights
are still on including the one which is part of the fan and the fan
itself can be switched back on.Puzzled as to how this can happen - and
where to start looking.-- bert

It would suggest that it's not supplied by the lighting circuit...

Are you sure that your RCD *only* protects the ring mains and not *all*
circuits such as cooker, lighting in addition to ring mains?

My understanding is that an RCD in the "fuse box" is usually upstream of the
ring main MCBs (over-current sensors, equivalent to wire fuses) and protects
the whole house. Our previous house had two RCDs: one was a separate unit
that was between the meter and the fuse box, and the other was within the
fuse box. Even if the RCD within the fuse box was tripped, all power went
off, including to non-ring-main circuits such as lighting and cooker.


What happens if you manually turn off the RCD? Does the lighting still
continue working?

On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?



--
Regards, Paul Herber
http://www.paulherber.co.uk/

On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was leakage to
earth and it wouldn't affect other circuit unless they also had an earth
leakage problem as RCDs aren't connect to earth.

On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was leakage to
earth and it wouldn't affect other circuit unless they also had an earth
leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within the
consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The only
thing that's really surprising (to me) is that the RCD protecting the
lighting circuit does not trip.

(I may be making a fool of myself here. Hope not!)

On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting
circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was leakage
to earth and it wouldn't affect other circuit unless they also had an
earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within the
consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The only
thing that's really surprising (to me) is that the RCD protecting the
lighting circuit does not trip.

I wouldn't assume there there is an RCD protecting the lighting circuit.
Very many homes don't have them.

(I may be making a fool of myself here. Hope not!)






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

On Thursday, 28 February 2019 12:26:10 UTC, bert wrote:
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.
--
bert

Neutral-Earth faults can trip the RCD.

"Tim+" wrote in message
...
bert Wrote in message:
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.In the past few nights a
couple of times when switching it off the RCD protecting the ring mains
has tripped. But the lighting circuits don't go through it and the lights
are still on including the one which is part of the fan and the fan
itself can be switched back on.Puzzled as to how this can happen - and
where to start looking.-- bert

It would suggest that it's not supplied by the lighting circuit...

Doesn't explain why it can be switched on again when the RCD trips.

On 28/02/2019 16:44, Robin wrote:
On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting
circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was leakage
to earth and it wouldn't affect other circuit unless they also had an
earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within
the consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The
only thing that's really surprising (to me) is that the RCD protecting
the lighting circuit does not trip.

I wouldn't assume there there is an RCD protecting the lighting circuit.
Â*Very many homes don't have them.

Of course the 18th edition has altered that for future installs (I think
you are correct about the OPs lights)

Just for info and not related to the OPs question. Domestic properties
are now required to have RCD protection on the lighting circuits even if
the cables are run in a manner or of the type that would not require RCD
protection (eg in trunking or SWA)


--


Adam

On 28/02/2019 18:02, ARW wrote:
On 28/02/2019 16:44, Robin wrote:
On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting
circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the
RCD
protecting the ring mains has tripped. But the lighting circuits
don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was
leakage to earth and it wouldn't affect other circuit unless they
also had an earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within
the consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The
only thing that's really surprising (to me) is that the RCD
protecting the lighting circuit does not trip.

I wouldn't assume there there is an RCD protecting the lighting
circuit. Â*Â*Very many homes don't have them.

Of course the 18th edition has altered that for future installs (I think
you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the lighting
circuit? Perhaps it's a more refined way to die.




Just for info and not related to the OPs question. Domestic properties
are now required to have RCD protection on the lighting circuits even if
the cables are run in a manner or of the type that would not require RCD
protection (eg in trunking or SWA)


--


Adam

Where is the switch for the fan, in the fan/light itself?
I'd start there.
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.!
"bert" wrote in message
...
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't go
through it and the lights are still on including the one which is part of
the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.
--
bert

I was thinking of back EMF.
That could make it back through the lights to the other circuits as a
spike of some kind.
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.!
"Tim+" wrote in message
...
bert Wrote in message:
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.In the past few nights a
couple of times when switching it off the RCD protecting the ring mains
has tripped. But the lighting circuits don't go through it and the lights
are still on including the one which is part of the fan and the fan
itself can be switched back on.Puzzled as to how this can happen - and
where to start looking.-- bert

It would suggest that it's not supplied by the lighting circuit...

Tim
--
Please don't feed the trolls

Yes those were my thought s as well.
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.!
"Clive Arthur" wrote in message
...
On 28/02/2019 12:21, bert wrote:
In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't go
through it and the lights are still on including the one which is part of
the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Possibly a suppressor in the motor has failed and the resulting inductive
spike is coupling into an adjacent circuit. Makes sense as you say it
doesn't always happen, probably only when the voltage happens to be on a
high part of the AC cycle.

Cheers
--
Clive

On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the lighting
circuit? Perhaps it's a more refined way to die.

Lighting circuits have generally been classed as safe without RCD
protection. For some reason domestic lighting circuits they are now
unsafe without RCD protection.

The RCD, when it first came into general use was for outside sockets and
using the lawnmower etc. Remember the RCD 13A plug in breakers before
RCDs were common place in CUs?


--
Adam

On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:
On 28/02/2019 16:44, Robin wrote:
On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting
circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off
the RCD
protecting the ring mains has tripped. But the lighting circuits
don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was
leakage to earth and it wouldn't affect other circuit unless they
also had an earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within
the consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The
only thing that's really surprising (to me) is that the RCD
protecting the lighting circuit does not trip.

I wouldn't assume there there is an RCD protecting the lighting
circuit. Â*Â*Very many homes don't have them.

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the lighting
circuit? Perhaps it's a more refined way to die.


It used to be on the basis of cost-effectiveness: the number of death
and serious injuries from lighting circuits was much less than from
sockets, showers, cookers etc.

I have no idea if the cost-effectiveness has changed with cheaper RCDs
(bearing in mind there are also now safer light fittings and less need
to change bulbs) as those who decided such things don't see fit to
publish their assessments of costs and benefits of changes - if they
even bother to make them rather than going with what they just know
makes sense.


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

On 28/02/2019 18:36, ARW wrote:


The RCD, when it first came into general use was for outside sockets and
using the lawnmower etc. Remember the RCD 13A plug in breakers before
RCDs were common place in CUs?


I still have a plug-in RCD which I use when working outside. It started
off as 30mA but now reliably trips with less than 10mA so usually saves
me a walk to the CU. I only wish we could such in the UK (as I think
someone raised here before).



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

On 28/02/2019 18:36, ARW wrote:
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the
lighting circuit? Perhaps it's a more refined way to die.

Lighting circuits have generally been classed as safe without RCD
protection. For some reason domestic lighting circuits they are now
unsafe without RCD protection.

The RCD, when it first came into general use was for outside sockets and
using the lawnmower etc. Remember the RCD 13A plug in breakers before
RCDs were common place in CUs?



Our CU was replaced in 1998, and no RCDs for us. We have a couple of
those RCD adapters. I have no idea whether they work, though, as they've
never tripped.

The CU looks like one of these:
https://www.screwfix.com/p/crabtree-...mer-unit/5823p

But it must be the 1998 version. There are 11 ways in use. Do you think
I can fit a couple of RCDs in?

On 28/02/2019 18:57, GB wrote:
On 28/02/2019 18:36, ARW wrote:
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the
lighting circuit? Perhaps it's a more refined way to die.

Lighting circuits have generally been classed as safe without RCD
protection. For some reason domestic lighting circuits they are now
unsafe without RCD protection.

The RCD, when it first came into general use was for outside sockets
and using the lawnmower etc. Remember the RCD 13A plug in breakers
before RCDs were common place in CUs?



Our CU was replaced in 1998, and no RCDs for us. We have a couple of
those RCD adapters. I have no idea whether they work, though, as they've
never tripped.

The CU looks like one of these:
https://www.screwfix.com/p/crabtree-...mer-unit/5823p


But it must be the 1998 version. There are 11 ways in use. Do you think
I can fit a couple of RCDs in?

If the Starbreaker has the plug in MCBs it may be possible to fit a
couple of RCBOs.

I was fitting RCD CUs well before 1998.

A photo of your actual CU will help me decide if you can fit an RCBO
(height restrictions apply).

As for your plug in RCD breakers. They should have a test button. This
is nothing more than a switch to imbalance the load via a resistor. It
will not tell you if the RCD is tripping within the required times but
it will give you a guide as to it's ability to work.

--
Adam

On 28/02/2019 19:23, ARW wrote:
On 28/02/2019 18:57, GB wrote:
On 28/02/2019 18:36, ARW wrote:
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the
lighting circuit? Perhaps it's a more refined way to die.

Lighting circuits have generally been classed as safe without RCD
protection. For some reason domestic lighting circuits they are now
unsafe without RCD protection.

The RCD, when it first came into general use was for outside sockets
and using the lawnmower etc. Remember the RCD 13A plug in breakers
before RCDs were common place in CUs?



Our CU was replaced in 1998, and no RCDs for us. We have a couple of
those RCD adapters. I have no idea whether they work, though, as
they've never tripped.

The CU looks like one of these:
https://www.screwfix.com/p/crabtree-...mer-unit/5823p


But it must be the 1998 version. There are 11 ways in use. Do you
think I can fit a couple of RCDs in?

If the Starbreaker has the plug in MCBs it may be possible to fit a
couple of RCBOs.

I was fitting RCD CUs well before 1998.

A photo of your actual CU will help me decide if you can fit an RCBO
(height restrictions apply).

It looks low to me, but I'll check.

You're saying that probably the simplest way to do this is to swap all
the MCBs for RCBOs, provided they fit in the box? They are about £20
each though.


As for your plug in RCD breakers. They should have a test button. This
is nothing more than a switch to imbalance the load via a resistor. It
will not tell you if the RCD is tripping within the required times but
it will give you a guide as to it's ability to work.

Yes, I occasionally test them.

I recently had to throw one out because DW (at least I hope it was her,
not me) had half-plugged an electric fire into one. The heat generated
destroyed the plug and adapter.

On 28/02/2019 20:05, GB wrote:
On 28/02/2019 19:23, ARW wrote:
On 28/02/2019 18:57, GB wrote:
On 28/02/2019 18:36, ARW wrote:
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the
lighting circuit? Perhaps it's a more refined way to die.

Lighting circuits have generally been classed as safe without RCD
protection. For some reason domestic lighting circuits they are now
unsafe without RCD protection.

The RCD, when it first came into general use was for outside sockets
and using the lawnmower etc. Remember the RCD 13A plug in breakers
before RCDs were common place in CUs?



Our CU was replaced in 1998, and no RCDs for us. We have a couple of
those RCD adapters. I have no idea whether they work, though, as
they've never tripped.

The CU looks like one of these:
https://www.screwfix.com/p/crabtree-...mer-unit/5823p


But it must be the 1998 version. There are 11 ways in use. Do you
think I can fit a couple of RCDs in?

If the Starbreaker has the plug in MCBs it may be possible to fit a
couple of RCBOs.

I was fitting RCD CUs well before 1998.

A photo of your actual CU will help me decide if you can fit an RCBO
(height restrictions apply).

It looks low to me, but I'll check.


OK. So trying my best. If your CU looks like this

https://www.tlc-direct.co.uk/Products/CBSBI00218.html

Then RCBOs will probably fit.






--
Adam

On Thursday, 28 February 2019 18:43:15 UTC, Robin wrote:
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:
On 28/02/2019 16:44, Robin wrote:
On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting
circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off
the RCD
protecting the ring mains has tripped. But the lighting circuits
don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was
leakage to earth and it wouldn't affect other circuit unless they
also had an earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within
the consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The
only thing that's really surprising (to me) is that the RCD
protecting the lighting circuit does not trip.

I wouldn't assume there there is an RCD protecting the lighting
circuit. Â*Â*Very many homes don't have them.

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the lighting
circuit? Perhaps it's a more refined way to die.


It used to be on the basis of cost-effectiveness: the number of death
and serious injuries from lighting circuits was much less than from

a grand total of 1

sockets, showers, cookers etc.

20 or so per year

I have no idea if the cost-effectiveness has changed with cheaper RCDs
(bearing in mind there are also now safer light fittings and less need
to change bulbs) as those who decided such things don't see fit to
publish their assessments of costs and benefits of changes - if they
even bother to make them rather than going with what they just know
makes sense.

it doesn't save any lives from shock. Whether it prevents any fires I can't say.


NT

On 28/02/2019 18:02, ARW wrote:
8

Just for info and not related to the OPs question. Domestic properties
are now required to have RCD protection on the lighting circuits even if
the cables are run in a manner or of the type that would not require RCD
protection (eg in trunking or SWA)



Does that apply to circuits that only have fixed none user accessible stuff?
It sounds like a half baked attempt to stop people putting their fingers
in a socket getting killed.

In article , Tim+
writes
bert Wrote in message:
In one bedroom we have a ceiling fan supplied from the lighting
circuit. It's been there for over 10 years no problems.In the past few
nights a couple of times when switching it off the RCD protecting the
ring mains has tripped. But the lighting circuits don't go through it
and the lights are still on including the one which is part of the fan
and the fan itself can be switched back on.Puzzled as to how this can
happen - and where to start looking.-- bert

It would suggest that it's not supplied by the lighting circuit...

Tim
But its definitely not supplied by any circuit protected by the RCD.
--
bert

In article , Clive Arthur
writes
On 28/02/2019 12:21, bert wrote:
In one bedroom we have a ceiling fan supplied from the lighting
circuit. It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the
RCD protecting the ring mains has tripped. But the lighting circuits
don't go through it and the lights are still on including the one
which is part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Possibly a suppressor in the motor has failed and the resulting
inductive spike is coupling into an adjacent circuit. Makes sense as
you say it doesn't always happen, probably only when the voltage
happens to be on a high part of the AC cycle.

Cheers
Now that is a possibility. Would explain why it has just started to
happen.
--
bert

In article
, Paul
Herber writes
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?



Are you suggesting that the qualified certified to whatever professional
electrician who did this has screwed up? Well actually his dozy
apprentice did most of the actual work 'til he fired him so yes quite
possible.
--
bert

In article , GB
writes
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?



Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.
It wouldn't actually matter where it was earthed if there was
leakage to earth and it wouldn't affect other circuit unless they
also had an earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within
the consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The only
thing that's really surprising (to me) is that the RCD protecting the
lighting circuit does not trip.

There's no rcd on the lighting circuits.
(I may be making a fool of myself here. Hope not!)





--
bert

In article , ARW
writes
On 28/02/2019 16:44, Robin wrote:
On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting
circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off the RCD
protecting the ring mains has tripped. But the lighting circuits don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was
leakage to earth and it wouldn't affect other circuit unless they
also had an earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause. Within
the consumer unit, all the lives and all the neutrals are connected
together, so there's scope for some coupling between circuits. The
only thing that's really surprising (to me) is that the RCD
protecting the lighting circuit does not trip.
I wouldn't assume there there is an RCD protecting the lighting
circuit. *Very many homes don't have them.


Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

He is. No rcd on lighting circuits. Personally I think they are as much
a liability as a help.
Just for info and not related to the OPs question. Domestic properties
are now required to have RCD protection on the lighting circuits even
if the cables are run in a manner or of the type that would not require
RCD protection (eg in trunking or SWA)


--


Adam

--
bert

In article , GB
writes
On 28/02/2019 18:02, ARW wrote:
On 28/02/2019 16:44, Robin wrote:
On 28/02/2019 15:00, GB wrote:
On 28/02/2019 14:38, dennis@home wrote:
On 28/02/2019 14:15, Paul Herber wrote:
On Thu, 28 Feb 2019 12:21:12 +0000, bert wrote:

In one bedroom we have a ceiling fan supplied from the lighting
circuit.
It's been there for over 10 years no problems.
In the past few nights a couple of times when switching it off
the RCD
protecting the ring mains has tripped. But the lighting circuits
don't
go through it and the lights are still on including the one which is
part of the fan and the fan itself can be switched back on.
Puzzled as to how this can happen - and where to start looking.

Earthed via a the ring-main circuit?




Probably not, RCDs don't just detect earth leakage but any current
imbalance between live and neutral.

It wouldn't actually matter where it was earthed if there was
leakage to earth and it wouldn't affect other circuit unless they
also had an earth leakage problem as RCDs aren't connect to earth.



Quite agree. I think Clive is probably right as to the cause.
Within the consumer unit, all the lives and all the neutrals are
connected together, so there's scope for some coupling between
circuits. The only thing that's really surprising (to me) is that
the RCD protecting the lighting circuit does not trip.

I wouldn't assume there there is an RCD protecting the lighting
circuit. **Very many homes don't have them.
Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)

Is that on the basis that it's okay to get electrocuted by the lighting
circuit? Perhaps it's a more refined way to die.


Very limited opportunities to be electrocuted by a lighting circuit
compared to a ring main.

Just for info and not related to the OPs question. Domestic
properties are now required to have RCD protection on the lighting
circuits even if the cables are run in a manner or of the type that
would not require RCD protection (eg in trunking or SWA)
-- Adam


--
bert

In article , ARW
writes
On 28/02/2019 18:12, GB wrote:
On 28/02/2019 18:02, ARW wrote:

Of course the 18th edition has altered that for future installs (I
think you are correct about the OPs lights)
Is that on the basis that it's okay to get electrocuted by the
lighting circuit? Perhaps it's a more refined way to die.

Lighting circuits have generally been classed as safe without RCD
protection. For some reason domestic lighting circuits they are now
unsafe without RCD protection.

The RCD, when it first came into general use was for outside sockets
and using the lawnmower etc. Remember the RCD 13A plug in breakers
before RCDs were common place in CUs?


Still have one and recently put it into use. Had the lamp holder fail on
a metal table lamp. Managed eventually to get a new skirt for it which
was also metal. But the lamp was supplied with 2 core cable.
--
bert

One on the fan unit and one at the wall. I've checked the wall switch
and tightened up the neutral connection by a turn or two. I've
"instructed" (AKA pleaded with) swmbo to only use that switch for the
time being.
For reason best known to himself the electrician wired the extension
circuits live to the switches whereas the rest of the house is wired
live to the ceiling rose.
In article , Brian Gaff
writes
Where is the switch for the fan, in the fan/light itself?
I'd start there.
Brian


--
bert

On 28/02/2019 18:27, Brian Gaff wrote:
I was thinking of back EMF.
That could make it back through the lights to the other circuits as a
spike of some kind.
Brian

On 01/03/2019 10:17, dennis@home wrote:
On 28/02/2019 18:02, ARW wrote:
8

Just for info and not related to the OPs question. Domestic properties
are now required to have RCD protection on the lighting circuits even
if the cables are run in a manner or of the type that would not
require RCD protection (eg in trunking or SWA)



Does that apply to circuits that only have fixed none user accessible
stuff?
It sounds like a half baked attempt to stop people putting their fingers
in a socket getting killed.



It does apply to the fixed stuff.

However it's not actually a big game changer in the scheme of things.

The 17th edition more or less made RCD protection compulsory for most
new/altered domestic circuits so in 99% of cases this should not be a
bigger issue than following the 17th edition regs.

--


Adam