[David WE Roberts[_4_]]

Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.
New light half price from Homebase was the incentive :-)

Skip to the bottom if you wish to avoid the detailed route to disaster.

All going swimmingly at first - took the old fitting off the wall and noted
that the screw holes looked to be the same spacing as the new back plate, so
no drilling needed.

Noted that there were two cables coming in, with the red wires joined.
I knew where one cable went - switch by the door.
I assumed normal lighting circuit - one cable is power in, other cable is to
and from switch.
In this case the two reds commoned, so the two blacks are power when the
switch is closed.
Checked with my trusty analog multimeter and this seemd to be the case.
Confirmed on the downstairs lighting circuit by turning off circuit breaker
at the fuse box and finding no current afterwards.

Unwired and rewired and then tested, but the circuit breaker for the
downstairs lighting wouldn't reset.
Bugger - what did I do wrong?
Took the fitting off the wires - no change.
Took the back plate off the wall - no change.
Uncoupled the two red wires and the two earth wires and pushed the two sets
of wires apart.
This seemed to fix it.
??????
Double checked - one set of wires are power, others are to the switch.

O.K. - start again but slowly.
Wound the two earth wires together and slid the sleeving over.
Checked breaker - wouldn't reset.
Took off sleeving and seperated the two cables and spread the three wires in
each cable at 120 degrees to each other.
Breaker wouldn't reset.
Checked for obvious wire damage on live cable - no obvious sign.
Joggled cables.
Breaker wouldn't reset.

[Noted that whilst mucking about with cables and lighting breaker out, I did
get a belt off something.]

Back to the trusty multi-meter.

Checked all the wires for 240V a/c - nothing.
Checked switch cable with the 1ohm setting - switch open nothing, switched
closed open circuit between red and black.
O.K. - seems right.

Check between wires in power cable.
There seems to be open circuit between live and earth, neutral and earth,
and live and neutral.

My conclusion is that somehow in moving the wires around I have induced a
short between live, neutral and earth somewhere in the power wire which
disappears into the cavity wall to gawd knows where.
Have I missed anything which might be good news?

I assume the best result I can get is to lift the bedroom floor above the
cable exit in the wall and find a cable coming out of the inner wall and
going across to the light fitting under the centre of the floor.
Of course, it could go to the outside light or the hall light.
Or the lighting power may not be wired directly into the light fittings.

Whichever way it goes, I forsee a world of hurt.
To get at the light fittings from below, I have to deal with thoughfully
applied Artex which probably means breaking the light fittings to get at the
internals because the cover will not unscrew.
To get at the light fittings from above involves lifting carpets and
floorboards, and in the case of the front bedroom draining and disassembling
a super king size water bed.

So please tell me there is something simple and obvious I have overlooked
which is easy to fix.

Cheers

Dave R
--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[chudford]

On Nov 12, 3:06*pm, "David WE Roberts" wrote:
Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.
New light half price from Homebase was the incentive :-)

Skip to the bottom if you wish to avoid the detailed route to disaster.

All going swimmingly at first - took the old fitting off the wall and noted
that the screw holes looked to be the same spacing as the new back plate, so
no drilling needed.

Noted that there were two cables coming in, with the red wires joined.
I knew where one cable went - switch by the door.
I assumed normal lighting circuit - one cable is power in, other cable is to
and from switch.
In this case the two reds commoned, so the two blacks are power when the
switch is closed.
Checked with my trusty analog multimeter and this seemd to be the case.
Confirmed on the downstairs lighting circuit by turning off circuit breaker
at the fuse box and finding no current afterwards.

Unwired and rewired and then tested, but the circuit breaker for the
downstairs lighting wouldn't reset.
Bugger - what did I do wrong?
Took the fitting off the wires - no change.
Took the back plate off the wall - no change.
Uncoupled the two red wires and the two earth wires and pushed the two sets
of wires apart.
This seemed to fix it.
??????
Double checked - one set of wires are power, others are to the switch.

O.K. - start again but slowly.
Wound the two earth wires together and slid the sleeving over.
Checked breaker - wouldn't reset.
Took off sleeving and seperated the two cables and spread the three wires in
each cable at 120 degrees to each other.
Breaker wouldn't reset.
Checked for obvious wire damage on live cable - no obvious sign.
Joggled cables.
Breaker wouldn't reset.

[Noted that whilst mucking about with cables and lighting breaker out, I did
get a belt off something.]

Back to the trusty multi-meter.

Checked all the wires for 240V a/c - nothing.
Checked switch cable with the 1ohm setting - switch open nothing, switched
closed open circuit between red and black.
O.K. - seems right.

Check between wires in power cable.
There seems to be open circuit between live and earth, neutral and earth,
and live and neutral.

My conclusion is that somehow in moving the wires around I have induced a
short between live, neutral and earth somewhere in the power wire which
disappears into the cavity wall to gawd knows where.
Have I missed anything which might be good news?

I assume the best result I can get is to lift the bedroom floor above the
cable exit in the wall and find a cable coming out of the inner wall and
going across to the light fitting under the centre of the floor.
Of course, it could go to the outside light or the hall light.
Or the lighting power may not be wired directly into the light fittings.

Whichever way it goes, I forsee a world of hurt.
To get at the light fittings from below, I have to deal with thoughfully
applied Artex which probably means breaking the light fittings to get at the
internals because the cover will not unscrew.
To get at the light fittings from above involves lifting carpets and
floorboards, and in the case of the front bedroom draining and disassembling
a super king size water bed.

So please tell me there is something simple and obvious I have overlooked
which is easy to fix.

Cheers

Dave R
--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

Hi
Have you checked the switch?
Your shorting of the various cables may have welded the contacts.

[David WE Roberts[_4_]]

"chudford" wrote in message
...
On Nov 12, 3:06 pm, "David WE Roberts" wrote:
Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.
snip

*Hi
*Have you checked the switch?
*Your shorting of the various cables may have welded the contacts.

Not sure which switch you are talking about.
As noted in the original post the switch for the light has been checked and
the fault shows when the switch is isolated from the circuit.
So the fault must be in the power circuit or elsewhere in the downstairs
lighting.
Personally I've never seen contacts in a switch welded - circuit breaker
should prevent this.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[chudford]

On Nov 12, 4:07*pm, "David WE Roberts" wrote:
"chudford" wrote in message

...
On Nov 12, 3:06 pm, "David WE Roberts" wrote: Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.

snip

*Hi
*Have you checked the switch?
*Your shorting of the various cables may have welded the contacts.

Not sure which switch you are talking about.
As noted in the original post the switch for the light has been checked and
the fault shows when the switch is isolated from the circuit.
So the fault must be in the power circuit or elsewhere in the downstairs
lighting.
Personally I've never seen contacts in a switch welded - circuit breaker
should prevent this.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

I speak from experience when sorting out a problem at my daughter's
house.
My son in law had connected up a light fitting incorrectly and had
wired the light switch between the live and neutral at the light
fitting.
This had welded the switch contacts. Took me ages to find the fault as
I had wrongly assumed that the switch must be OK.
This was on a RCD protected circuit.

[Ian[_9_]]

"David WE Roberts" wrote in message
...
Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.
New light half price from Homebase was the incentive :-)

Skip to the bottom if you wish to avoid the detailed route to disaster.

All going swimmingly at first - took the old fitting off the wall and
noted that the screw holes looked to be the same spacing as the new back
plate, so no drilling needed.

Noted that there were two cables coming in, with the red wires joined.
I knew where one cable went - switch by the door.
I assumed

That's where you went wrong........




normal lighting circuit - one cable is power in, other cable is to
and from switch.
In this case the two reds commoned, so the two blacks are power when the
switch is closed.
Checked with my trusty analog multimeter and this seemd to be the case.
Confirmed on the downstairs lighting circuit by turning off circuit
breaker at the fuse box and finding no current afterwards.

Unwired and rewired and then tested, but the circuit breaker for the
downstairs lighting wouldn't reset.
Bugger - what did I do wrong?
Took the fitting off the wires - no change.
Took the back plate off the wall - no change.
Uncoupled the two red wires and the two earth wires and pushed the two
sets of wires apart.
This seemed to fix it.
??????
Double checked - one set of wires are power, others are to the switch.

O.K. - start again but slowly.
Wound the two earth wires together and slid the sleeving over.
Checked breaker - wouldn't reset.
Took off sleeving and seperated the two cables and spread the three wires
in each cable at 120 degrees to each other.
Breaker wouldn't reset.
Checked for obvious wire damage on live cable - no obvious sign.
Joggled cables.
Breaker wouldn't reset.

[Noted that whilst mucking about with cables and lighting breaker out, I
did get a belt off something.]

Back to the trusty multi-meter.

Checked all the wires for 240V a/c - nothing.
Checked switch cable with the 1ohm setting - switch open nothing, switched
closed open circuit between red and black.
O.K. - seems right.

Check between wires in power cable.
There seems to be open circuit between live and earth, neutral and earth,
and live and neutral.

My conclusion is that somehow in moving the wires around I have induced a
short between live, neutral and earth somewhere in the power wire which
disappears into the cavity wall to gawd knows where.
Have I missed anything which might be good news?

I assume the best result I can get is to lift the bedroom floor above the
cable exit in the wall and find a cable coming out of the inner wall and
going across to the light fitting under the centre of the floor.
Of course, it could go to the outside light or the hall light.
Or the lighting power may not be wired directly into the light fittings.

Whichever way it goes, I forsee a world of hurt.
To get at the light fittings from below, I have to deal with thoughfully
applied Artex which probably means breaking the light fittings to get at
the internals because the cover will not unscrew.
To get at the light fittings from above involves lifting carpets and
floorboards, and in the case of the front bedroom draining and
disassembling a super king size water bed.

So please tell me there is something simple and obvious I have overlooked
which is easy to fix.

Cheers

Dave R
--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[ARWadsworth]

David WE Roberts wrote:
"chudford" wrote in message
...
On Nov 12, 3:06 pm, "David WE Roberts" wrote:
Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up
the ghost.
snip

*Hi
*Have you checked the switch?
*Your shorting of the various cables may have welded the contacts.

Not sure which switch you are talking about.
As noted in the original post the switch for the light has been
checked and the fault shows when the switch is isolated from the
circuit. So the fault must be in the power circuit or elsewhere in the
downstairs lighting.




Personally I've never seen contacts in a switch welded - circuit
breaker should prevent this.

Trust me, the circuit breaker will not prevent this.

The bit about getting a belt whilst the breaker is removed is scary. Is
there just one light?

I would suggest trying to connect the light straight into the "power" supply
to see what happens and then try swapping the new light for a pendant for
testing purposes (it could be a faulty PIR light).

--
Adam

[ARWadsworth]

chudford wrote:
On Nov 12, 4:07 pm, "David WE Roberts" wrote:
"chudford" wrote in message

...
On Nov 12, 3:06 pm, "David WE Roberts"
wrote: Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given
up the ghost.

snip

*Hi
*Have you checked the switch?
*Your shorting of the various cables may have welded the contacts.

Not sure which switch you are talking about.
As noted in the original post the switch for the light has been
checked and
the fault shows when the switch is isolated from the circuit.
So the fault must be in the power circuit or elsewhere in the
downstairs
lighting.
Personally I've never seen contacts in a switch welded - circuit
breaker
should prevent this.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

I speak from experience when sorting out a problem at my daughter's
house.
My son in law had connected up a light fitting incorrectly and had
wired the light switch between the live and neutral at the light
fitting.
This had welded the switch contacts. Took me ages to find the fault as
I had wrongly assumed that the switch must be OK.
This was on a RCD protected circuit.

A RCD trips on earth faults. You had a LN short.



--
Adam

[crb]

Checked all the wires for 240V a/c - nothing.

Interesting. How did you measure the 240v - between what and what?

Try measuring again between each wire in turn and a known good earth,
both with the CB engaged and tripped.

crb

[David WE Roberts[_4_]]

"crb" wrote in message
...

Checked all the wires for 240V a/c - nothing.

Interesting. How did you measure the 240v - between what and what?

Try measuring again between each wire in turn and a known good earth,
both with the CB engaged and tripped.


Interesting thought - however I can't test with the CB engaged because it
always trips.
For those reading this, please note that the fault manifests with no light
fitting attached and no switch attached.
Just bare wires out of the wall, and the two cables (power and switch)
clearly seperated.
So it cannot be a fault in the light fitting or switch.
The fault is inwards of the power cable coming from the rest of the
downstairs lighting circuit.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[David WE Roberts[_4_]]

"ARWadsworth" wrote in message
...
David WE Roberts wrote:
"chudford" wrote in message
...
On Nov 12, 3:06 pm, "David WE Roberts" wrote:
Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up
the ghost.
snip

*Hi
*Have you checked the switch?
*Your shorting of the various cables may have welded the contacts.

Not sure which switch you are talking about.
As noted in the original post the switch for the light has been
checked and the fault shows when the switch is isolated from the
circuit. So the fault must be in the power circuit or elsewhere in the
downstairs lighting.




Personally I've never seen contacts in a switch welded - circuit
breaker should prevent this.

Trust me, the circuit breaker will not prevent this.

The bit about getting a belt whilst the breaker is removed is scary. Is
there just one light?

I would suggest trying to connect the light straight into the "power"
supply to see what happens and then try swapping the new light for a
pendant for testing purposes (it could be a faulty PIR light).


Yes, the belt worried me too.
As stated elsewhere the fault is present with no switch or light attached
which rules out the switch and the light fitting as causes.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[jgharston]

David WE Roberts wrote:
So please tell me there is something simple and obvious I have overlooked
which is easy to fix.

Identify and isolate the cable at the consumer unit end, then
neatly chuck a supply through an upstairs window and plug it
into a socket outlet. Make note to rip up floorboards next
time place is being redecorated and replace with fixed wiring.

I have sympathy. I got a belt from an upstairs landing light
that I was *sure* I'd isolated as I'd pulled the fuse, only
to discover that it had been wired to both the "upstairs" fuse
and the "downstairs" fuse. The previous owner had obviously
thought: the stairs have an upstairs light and a downstairs
light, so of course it has to be wired to both fuses, doesn't it?

JGH

[ARWadsworth]

David WE Roberts wrote:
"crb" wrote in message
...

Checked all the wires for 240V a/c - nothing.

Interesting. How did you measure the 240v - between what and what?

Try measuring again between each wire in turn and a known good earth,
both with the CB engaged and tripped.


Interesting thought - however I can't test with the CB engaged
because it always trips.
For those reading this, please note that the fault manifests with no
light fitting attached and no switch attached.
Just bare wires out of the wall, and the two cables (power and switch)
clearly seperated.
So it cannot be a fault in the light fitting or switch.
The fault is inwards of the power cable coming from the rest of the
downstairs lighting circuit.

A twin and earth cable that has been cut using a stanley knife!

--
Adam

[David WE Roberts[_4_]]

"ARWadsworth" wrote in message
...
David WE Roberts wrote:
"crb" wrote in message
...

Checked all the wires for 240V a/c - nothing.

Interesting. How did you measure the 240v - between what and what?

Try measuring again between each wire in turn and a known good earth,
both with the CB engaged and tripped.


Interesting thought - however I can't test with the CB engaged
because it always trips.
For those reading this, please note that the fault manifests with no
light fitting attached and no switch attached.
Just bare wires out of the wall, and the two cables (power and switch)
clearly seperated.
So it cannot be a fault in the light fitting or switch.
The fault is inwards of the power cable coming from the rest of the
downstairs lighting circuit.

A twin and earth cable that has been cut using a stanley knife!


However since the fault is inbound of anything I've touched, it wasn't me,
guvnor.
Added probem is that the central heating seems to be powered from the
downstairs lighting, whic I will describe in another post.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[David WE Roberts[_4_]]

"jgharston" wrote in message
...
David WE Roberts wrote:
So please tell me there is something simple and obvious I have overlooked
which is easy to fix.

Identify and isolate the cable at the consumer unit end, then
neatly chuck a supply through an upstairs window and plug it
into a socket outlet. Make note to rip up floorboards next
time place is being redecorated and replace with fixed wiring.

I have sympathy. I got a belt from an upstairs landing light
that I was *sure* I'd isolated as I'd pulled the fuse, only
to discover that it had been wired to both the "upstairs" fuse
and the "downstairs" fuse. The previous owner had obviously
thought: the stairs have an upstairs light and a downstairs
light, so of course it has to be wired to both fuses, doesn't it?


Not sure this is going to help me - the entire downstairs lighting circuit
is off and the cable where I believe the fault has manifested disappears
into the cavity wall.

If normal lighting practice has been followed then this cable will go to a
junction either in a junction box or in a ceiling rose where it will join
the main lighting power circuit.

I am assuming that if I can find where the power feed joins the rest of the
circuit I can isolate it and everything else will then work.

Finding the other end is the issue.

The challenge is not to get the outside light to work.
It is to get the circuit breaker to close and the rest of the downstairs
lighting to work.
--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[The Medway Handyman]

On 12/11/2011 16:20, chudford wrote:
On Nov 12, 4:07 pm, "David WE wrote:
wrote in message

...
On Nov 12, 3:06 pm, "David WE wrote: Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.

snip

*Hi
*Have you checked the switch?
*Your shorting of the various cables may have welded the contacts.

Not sure which switch you are talking about.
As noted in the original post the switch for the light has been checked and
the fault shows when the switch is isolated from the circuit.
So the fault must be in the power circuit or elsewhere in the downstairs
lighting.
Personally I've never seen contacts in a switch welded - circuit breaker
should prevent this.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

I speak from experience when sorting out a problem at my daughter's
house.
My son in law had connected up a light fitting incorrectly and had
wired the light switch between the live and neutral at the light
fitting.
This had welded the switch contacts. Took me ages to find the fault as
I had wrongly assumed that the switch must be OK.


I have done the same.


--
Dave - The Medway Handyman www.medwayhandyman.co.uk

[David WE Roberts[_4_]]

"David WE Roberts" wrote in message
...
Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.
New light half price from Homebase was the incentive :-)

snip
My conclusion is that somehow in moving the wires around I have induced a
short between live, neutral and earth somewhere in the power wire which
disappears into the cavity wall to gawd knows where.
Have I missed anything which might be good news?
snip

I was double checking that the central heating was off the lighting circuit
by taking the CB up half way (this gives power - full up trips) whilst
someone watched the programmer for signs of life.

I had just used this trick to locate any lights still turned on and turn
them off.
To my surprise, after I heard the boiler fire up the breaker stayed set.

So I am now wondering if the CH was just putting too much load on the CB
when first reset - the initial suge knocking it over again.

So the thing I do need to confirm - in a power cable from a lighting circuit
where some lights may be turned on should I see an open circuit between live
and neutral?
Doesn't seem right to me.
Seems more likely that a small contact has burned itself out during the
repeated short power ups.

I am now not going to touch anything until it is daylight and the house is
toasty warm.

Then presumably I play hunt the phantom fault.

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

(\__/)
(='.'=)
(")_(")

[John Rumm]

On 12/11/2011 17:13, David WE Roberts wrote:

"crb" wrote in message
...

Checked all the wires for 240V a/c - nothing.

Interesting. How did you measure the 240v - between what and what?

Try measuring again between each wire in turn and a known good earth,
both with the CB engaged and tripped.


Interesting thought - however I can't test with the CB engaged because
it always trips.
For those reading this, please note that the fault manifests with no
light fitting attached and no switch attached.
Just bare wires out of the wall, and the two cables (power and switch)
clearly seperated.
So it cannot be a fault in the light fitting or switch.
The fault is inwards of the power cable coming from the rest of the
downstairs lighting circuit.

Could it be your fixing screws were longer than the previous ones?
Perhaps the cable is routed in such a way as a screw has damaged it. If
that were the case, at least the fault would be very close to the light.

Another possibility is the MCB is faulty. What happens if you disconnect
the circuit wires from the top of the MCB - will it reset then?


--
Cheers,

John.

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

[js.b1]

Go on Ebay and buy a Fluke Voltalert.

[NT[_2_]]

On Nov 12, 6:05*pm, "David WE Roberts" wrote:
"David WE Roberts" wrote in ... Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.
New light half price from Homebase was the incentive :-)

snip
My conclusion is that somehow in moving the wires around I have induced a
short between live, neutral and earth somewhere in the power wire which
disappears into the cavity wall to gawd knows where.
Have I missed anything which might be good news?

snip

I was double checking that the central heating was off the lighting circuit
by taking the CB up half way (this gives power - full up trips) whilst
someone watched the programmer for signs of life.

I had just used this trick to locate any lights still turned on and turn
them off.
To my surprise, after I heard the boiler fire up the breaker stayed set.

So I am now wondering if the CH was just putting too much load on the CB
when first reset - the initial suge knocking it over again.

So the thing I do need to confirm - in a power cable from a lighting circuit
where some lights may be turned on should I see an open circuit between live
and neutral?
Doesn't seem right to me.
Seems more likely that a small contact has burned itself out during the
repeated short power ups.

I am now not going to touch anything until it is daylight and the house is
toasty warm.

Then presumably I play hunt the phantom fault.

The whole account of full of question marks. I'd disconnect the CU end
of teh cable, and use a multimeter to check what the circuit is doing,
plus establish what all the wires are at the light end. Ultimately if
it cant be fixed, run new cable, but hopefully you can find &
disconnect the faulty part of the circuit. We cant, its jsut a case of
test, divide & conquer.


NT

[Grimly Curmudgeon]

On Sat, 12 Nov 2011 16:24:38 -0000, "ARWadsworth"
wrote:

The bit about getting a belt whilst the breaker is removed is scary.

Floating neutral - fecking things. Had a mild jolt or two from those.

[Dave Liquorice[_3_]]

On Sat, 12 Nov 2011 17:23:34 -0000, David WE Roberts wrote:

However since the fault is inbound of anything I've touched, it wasn't
me, guvnor.

But you have pulled and waggled the cable which may have caused a
problem hidden in the wall. Either snagged on something that has cut
through the insualtion (but the "something" would have to be pretty
sharp or you have been very rough...). Or mice have nibbled away the
insulation and the pulling has created a short.

Added probem is that the central heating seems to be powered from the
downstairs lighting, whic I will describe in another post.

Seems the wiring in this house is not of a particulary high standard.

--
Cheers
Dave.

[David WE Roberts[_4_]]

"David WE Roberts" wrote in message
...

"David WE Roberts" wrote in message
...
Just set off to do my good deed of the day.
Replacing the PIR outside light by the front door which had given up the
ghost.
New light half price from Homebase was the incentive :-)

snip
My conclusion is that somehow in moving the wires around I have induced a
short between live, neutral and earth somewhere in the power wire which
disappears into the cavity wall to gawd knows where.
Have I missed anything which might be good news?
snip

I was double checking that the central heating was off the lighting
circuit by taking the CB up half way (this gives power - full up trips)
whilst someone watched the programmer for signs of life.

I had just used this trick to locate any lights still turned on and turn
them off.
To my surprise, after I heard the boiler fire up the breaker stayed set.

So I am now wondering if the CH was just putting too much load on the CB
when first reset - the initial suge knocking it over again.

So the thing I do need to confirm - in a power cable from a lighting
circuit where some lights may be turned on should I see an open circuit
between live and neutral?
Doesn't seem right to me.
Seems more likely that a small contact has burned itself out during the
repeated short power ups.

I am now not going to touch anything until it is daylight and the house is
toasty warm.

Then presumably I play hunt the phantom fault.


After a good night's sleep in a warm house I have had further thoughts.
I think I have had a phantom problem and gone too far seeking a solution.

Firstly, I think that the main issue was that the CH was trying to fire up
when I reset the breaker, and the initial surge was too much for the breaker
to cope with. After a few tries and holding the switch half way the breaker
reset O.K. and has been fine overnight. [JR suggested the problem might be
in the breaker.]

Secondly, in looking for a fault (which may not have been there) I was
trying too hard.
If there is a switch closed anywhere in the circuit (CH, a light, whatever)
then there is a route for the current to pass between live and neutral.
So a tester will show a connection between L&N.
So this isn't a fault, but expected behaviour.
I think.....

Now hoping that a sensitive breaker is the explanation for everything.

Thanks for all the suggestions.

Dave R

--
No plan survives contact with the enemy.
[Not even bunny]

Helmuth von Moltke the Elder

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