Several (but not all) lights on one lighting circuit in my house
have stopped working.
I asked on this newsgroup about the problem,
and received many useful suggestions,
particularly pointers to the circuit diagrams at
http://wiki.diyfaq.org.uk/index.php?...ers#Overvie w
and
http://wiki.diyfaq.org.uk/index.php?...ers#Lightin g

I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.
Unfortunately replacing the connection seems to require
a lot of work - either removing some of the wooden ceiling
between the 2 lights (about 4 metres apart)
or pulling up the carpet in the room above,
and removing some of the floor-boards.

We have visitors staying next week,
and one of the rooms with no light is the bathroom,
so I am thinking of effecting a temporary kludge.

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?

--
Timothy Murphy
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

On Oct 8, 1:24*pm, Timothy Murphy wrote:
Several (but not all) lights on one lighting circuit in my house
have stopped working.
I asked on this newsgroup about the problem,
and received many useful suggestions,
particularly pointers to the circuit diagrams athttp://wiki.diyfaq.org.uk/index.php?title=House_Wiring_for_Beginners#...
andhttp://wiki.diyfaq.org.uk/index.php?title=House_Wiring_for_Beginners#...

I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.
Unfortunately replacing the connection seems to require
a lot of work - either removing some of the wooden ceiling
between the 2 lights (about 4 metres apart)
or pulling up the carpet in the room above,
and removing some of the floor-boards.

We have visitors staying next week,
and one of the rooms with no light is the bathroom,
so I am thinking of effecting a temporary kludge.

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?

Lets look at the issues.

It would move protection of the faulty circuit from the 5/6A lighting
mcb to the 30/32A socket mcb and 2-13A plug fuse. If the broken
circuit reconnects, the whole lot would then be on plug fuse in series
with 32A mcb all in parallel with a 6A mcb. Its certainly not
compliant.

If fixed securely, there is then risk involved if the system were
worked on by people aware of the setup. Wrong plug fusing is
relatively minor in that 1mm cable can manage on 13A using, albeit
with prolonged disconnect times an issue.

If the CU is split circuit, there would be an added risk that one side
of the CU would feed power to after the switch on the other CU side,
which is a more significant risk than the other things.

Some people dont mind such risks and legal questionables, and there
are surely worse setups in use. I couldnt recommend it.


NT

"Timothy Murphy" wrote in message
...
Several (but not all) lights on one lighting circuit in my house
have stopped working.
I asked on this newsgroup about the problem,
and received many useful suggestions,
particularly pointers to the circuit diagrams at
http://wiki.diyfaq.org.uk/index.php?...ers#Overvie w
and
http://wiki.diyfaq.org.uk/index.php?...ers#Lightin g

I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.
Unfortunately replacing the connection seems to require
a lot of work - either removing some of the wooden ceiling
between the 2 lights (about 4 metres apart)
or pulling up the carpet in the room above,
and removing some of the floor-boards.

We have visitors staying next week,
and one of the rooms with no light is the bathroom,
so I am thinking of effecting a temporary kludge.

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?



Yes .. you are mixing up power & lighting.

If you totally isolate the particular lights so there is no way power &
lighting circuits are or can be missed up, then you could think of it as if
a free standing lamp, and protect via a 3A fuse.

The danger of course is that the temporary fix gets left in place and in
some years in future someone goes to work on lights having killed light cct
at CU, and does not know there is separate power feed .... not good news.

So the answer is can you do it, yes, should you do it .... no
Can you do it safely ... yes ...if you can totally isolate all of the
lighting cct ... but as you are unable to gain access (or you would fix the
problem) it would seem unlikely that you can be sure that you would not be
feeding 'power' into any other lighting cct.
Are all your sockets on an RCCD ? then you really should not go ahead with
this IMHO

In my house all AC outlets & lighting is RCCD protected


Why not simply give the room a couple of standard lamps plugged into AC
sockets until you can get around to fixing.

NT wrote:

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?

It would move protection of the faulty circuit from the 5/6A lighting
mcb to the 30/32A socket mcb and 2-13A plug fuse. If the broken
circuit reconnects, the whole lot would then be on plug fuse in series
with 32A mcb all in parallel with a 6A mcb. Its certainly not
compliant.

Thanks very much for your response.
I know what I am planning is "non-compliant".
It is intended as a purely temporary expedient.

If fixed securely, there is then risk involved if the system were
worked on by people aware of the setup. Wrong plug fusing is
relatively minor in that 1mm cable can manage on 13A using, albeit
with prolonged disconnect times an issue.

I'll certainly remove everything I put in
before calling in an electrician.
I've a feeling there may be some smart way of mending the circuit,
without involving too much dislocation,
and I'm asking around to see if I can find a clever electrician.



--
Timothy Murphy
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

On 08/10/2011 13:24, Timothy Murphy wrote:
Several (but not all) lights on one lighting circuit in my house
have stopped working.
I asked on this newsgroup about the problem,
and received many useful suggestions,
particularly pointers to the circuit diagrams at
http://wiki.diyfaq.org.uk/index.php?...ers#Overvie w
and
http://wiki.diyfaq.org.uk/index.php?...ers#Lightin g

I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.
Unfortunately replacing the connection seems to require
a lot of work - either removing some of the wooden ceiling
between the 2 lights (about 4 metres apart)
or pulling up the carpet in the room above,
and removing some of the floor-boards.

We have visitors staying next week,
and one of the rooms with no light is the bathroom,
so I am thinking of effecting a temporary kludge.

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?

A battery operated light, as sold for cupboards etc., would be the
safest option.

Colin Bignell

Rick Hughes wrote:

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?

Why not simply give the room a couple of standard lamps plugged into AC
sockets until you can get around to fixing.

The room most affected is the bathroom;
and putting a standard lamp in there seemed to me more dangerous
than what I am suggesting.

--
Timothy Murphy
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

"Timothy Murphy" wrote in message
...
Rick Hughes wrote:

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?

Why not simply give the room a couple of standard lamps plugged into AC
sockets until you can get around to fixing.

The room most affected is the bathroom;
and putting a standard lamp in there seemed to me more dangerous
than what I am suggesting.


Then if it is a bathroom ... that is a non-no

Personally I would not advise a bodge on any bathroom cct .... do it right
or use battery powered lights until you can .... B&Q sell ones designed for
lofts & under stairs ...

A battery operated light, as sold for cupboards etc., would be the
safest option.

Colin Bignell

One of the meaty "work lights" would be even better. I had a couple of
these and used to swear by them (bright, and long battery life)

http://www.machinemart.co.uk/shop/pr...=1&TC=SRC-work
light

but they both died on me. Can anyone recommend a bright LED work light
with a decent sized battery?

On Sat, 08 Oct 2011 15:50:55 +0100, Rick Hughes wrote:
Then if it is a bathroom ... that is a non-no

Was that a typo? A non-no would be a yes, a no-no would be a no. ;-)

In message , Timothy Murphy
writes


I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.

Did you work this out in theory or have you actually been into the
fittings and tested?

If you haven't been into the fittings then it maybe as simple as a loose
screw allowing the feed to the next light to become disconnected. Much
quicker to fix than your proposed temporary solution. Also rather a lot
safer :-)

--
Bill

On Sat, 08 Oct 2011 13:24:22 +0100, Timothy Murphy wrote:
I've worked out that there must be a break in the connection between 2
of the lights on this circuit. Unfortunately replacing the connection
seems to require a lot of work - either removing some of the wooden
ceiling between the 2 lights (about 4 metres apart) or pulling up the
carpet in the room above, and removing some of the floor-boards.

Do you think that the cable has just broken somewhere along its length
for some reason - or do you mean there's a hidden junction box somewhere
with a faulty connection? (over here junction boxes have to always be
accessible, but I don't recall if that was a UK requirement)

(cable breaks just seem quite unlikely, that's all, and I'd expect the
fault to be at a terminal, switch, fitting etc.)

What I am thinking of doing is removing the ceiling rose on one of the
affected lights, and adding a temporary connection to a power socket.

Is this a dangerous experiment?

It seems unwise to me without being able to inspect the actual fault -
you don't know what might be touching what in the non-working section,
and feeding power into it might have interesting consequences.

If you can see the fault and be sure you've completely isolated it then
it might be a different matter - but personally I'd be looking at other
ways of providing lighting as a temporary solution until I could fix
things properly.

cheers

Jules

On Sat, 8 Oct 2011 15:29:39 +0000 (UTC), Jules Richardson
wrote:

Then if it is a bathroom ... that is a non-no

Was that a typo? A non-no would be a yes, a no-no would be a no. ;-)

If it's a bathroom, I suspect he's poo-pooed the idea.

On 08/10/2011 16:40, Jules Richardson wrote:
On Sat, 08 Oct 2011 13:24:22 +0100, Timothy Murphy wrote:
I've worked out that there must be a break in the connection between 2
of the lights on this circuit. Unfortunately replacing the connection
seems to require a lot of work - either removing some of the wooden
ceiling between the 2 lights (about 4 metres apart) or pulling up the
carpet in the room above, and removing some of the floor-boards.

Do you think that the cable has just broken somewhere along its length
for some reason - or do you mean there's a hidden junction box somewhere
with a faulty connection? (over here junction boxes have to always be
accessible, but I don't recall if that was a UK requirement)

(cable breaks just seem quite unlikely, that's all, and I'd expect the
fault to be at a terminal, switch, fitting etc.)

IANAE but I was thinking along those lines as well. The bathroom may
well be the last light on the circuit?

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

On Sat, 08 Oct 2011 17:31:13 +0100, The Medway Handyman wrote:

On 08/10/2011 16:40, Jules Richardson wrote:
On Sat, 08 Oct 2011 13:24:22 +0100, Timothy Murphy wrote:
I've worked out that there must be a break in the connection between 2
of the lights on this circuit. Unfortunately replacing the connection
seems to require a lot of work - either removing some of the wooden
ceiling between the 2 lights (about 4 metres apart) or pulling up the
carpet in the room above, and removing some of the floor-boards.

Do you think that the cable has just broken somewhere along its length
for some reason - or do you mean there's a hidden junction box
somewhere with a faulty connection? (over here junction boxes have to
always be accessible, but I don't recall if that was a UK requirement)

(cable breaks just seem quite unlikely, that's all, and I'd expect the
fault to be at a terminal, switch, fitting etc.)

IANAE but I was thinking along those lines as well.

Well, rodents might do for a cable, or it might get squished by a
settling house, or some form of induced vibration (assuming not properly
affixed) over time etc. so I don't think a cable break's impossible -
just that other things are more likely culprits.

I missed the original thread on this, so I'm not sure what was advised
there or what the OP has checked.

The bathroom may well be the last light on the circuit?

Hmm, the post mentions 'one of the rooms with no light', so it sounds
like there's more than one light affected - but as it's most likely a
radial circuit (does it *have* to be in the UK? I'm not sure) then
anything downstream of the fault will be dead.

If it were me, at the very least I'd disconnect the damaged section at
the last-working fitting sharpish though, just so it's not supplying
mains on a wire that might have a bare end knocking around somewhere.

cheers

Jules

On 8 Oct,
The Medway Handyman wrote:

On 08/10/2011 16:40, Jules Richardson wrote:
On Sat, 08 Oct 2011 13:24:22 +0100, Timothy Murphy wrote:
I've worked out that there must be a break in the connection between 2
of the lights on this circuit. Unfortunately replacing the connection
seems to require a lot of work - either removing some of the wooden
ceiling between the 2 lights (about 4 metres apart) or pulling up the
carpet in the room above, and removing some of the floor-boards.

Do you think that the cable has just broken somewhere along its length
for some reason - or do you mean there's a hidden junction box somewhere
with a faulty connection? (over here junction boxes have to always be
accessible, but I don't recall if that was a UK requirement)

(cable breaks just seem quite unlikely, that's all, and I'd expect the
fault to be at a terminal, switch, fitting etc.)

IANAE but I was thinking along those lines as well. The bathroom may
well be the last light on the circuit?

Probably a light fitting has been replaced and the loop through or neutral
not connected correctly.

--
B Thumbs
Change lycos to yahoo to reply

Bill wrote:

I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.

Did you work this out in theory or have you actually been into the
fittings and tested?

Thanks for your (and all the other) responses.
This was in fact a purely theoretical deduction ...

If you haven't been into the fittings then it maybe as simple as a loose
screw allowing the feed to the next light to become disconnected. Much
quicker to fix than your proposed temporary solution. Also rather a lot
safer :-)

I've looked at all the ceiling roses that are affected,
particularly the last one working and the first one affected.
The connections on them all look fine to me.

Unfortunately for my experiment,
the ceiling roses are not as in the online diagram at
http://wiki.diyfaq.org.uk/index.php?...ers#Lightin g
and elsewhere online.
Each ceiling rose has two terminals on the ceiling side,
one of which has 3 incoming wires attached to it,
and the other has 1 incoming wire attached to it.
The two wires to the light are attached to the two terminals
underneath the rose.

The only way I can make sense of this is that the single wire
goes to the switch and thence to the live supply,
while the 3 wires are negative and go to the next light,
the last light and possibly the switch?

I should say the wiring is fairly old - 25 years -
but was installed by an electrician who I am sure
would have followed whatever rules were in place at the time.
(He worked for the electricity supply company.)
I checked in an electrical store here,
and the ceiling roses sold now are as shown in the online texts.

Any advice on this setup gratefully received.

But I'm tending to the advice offered by several posters
to get a temporary battery-operated light for the bathroom,
probably from B&Q.




--
Timothy Murphy
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

On 08/10/2011 16:40, Jules Richardson wrote:

Do you think that the cable has just broken somewhere along its length
for some reason - or do you mean there's a hidden junction box somewhere
with a faulty connection? (over here junction boxes have to always be
accessible, but I don't recall if that was a UK requirement)

Same rule applies here - any screw terminal connection must remain
accessible.

(cable breaks just seem quite unlikely, that's all, and I'd expect the
fault to be at a terminal, switch, fitting etc.)

+1

What I am thinking of doing is removing the ceiling rose on one of the
affected lights, and adding a temporary connection to a power socket.

Is this a dangerous experiment?

It seems unwise to me without being able to inspect the actual fault -
you don't know what might be touching what in the non-working section,
and feeding power into it might have interesting consequences.

Not only that, but if we assume the socket circuit has RCD protection
(possibly aka GFI on Jules' side of the pond), then feeding a partial
broken circuit sounds like a recipe for a tripped RCD due to having
unexpected return paths on the lighting circuit.

If you can see the fault and be sure you've completely isolated it then
it might be a different matter - but personally I'd be looking at other
ways of providing lighting as a temporary solution until I could fix
things properly.

+1


--
Cheers,

John.

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

On 09/10/2011 01:07, Timothy Murphy wrote:

Unfortunately for my experiment,
the ceiling roses are not as in the online diagram at
http://wiki.diyfaq.org.uk/index.php?...ers#Lightin g
and elsewhere online.

Each ceiling rose has two terminals on the ceiling side,

Could you clarify what you mean by "Ceiling side" (in fact a photo would
help)

one of which has 3 incoming wires attached to it,

If following a "loop in" style of wiring (which there is no guarantee
that it is), then this sounds plausible... probably neutral in, out, and
to lamp.

and the other has 1 incoming wire attached to it.

One terminal with one wire? Aside from stopping it waving about, that
does not sound quite right... is the terminal attached to anything else?

The two wires to the light are attached to the two terminals
underneath the rose.

Which two terminals underneath the rose?

I take it we are not talking about your stereotypical ceiling rose:

http://www.tlc-direct.co.uk/Images/P...ize_3/AACR.JPG

The only way I can make sense of this is that the single wire
goes to the switch and thence to the live supply,
while the 3 wires are negative and go to the next light,
the last light and possibly the switch?

You don't usually have a neutral at the switch unless doing the "loop
through switch" style wiring shown he

http://wiki.diyfaq.org.uk/index.php?... iring_Options

There is also the rarely used "Single and earth" lighting circuit:

http://wiki.diyfaq.org.uk/index.php?...ngle_.26_earth

I should say the wiring is fairly old - 25 years -
but was installed by an electrician who I am sure
would have followed whatever rules were in place at the time.
(He worked for the electricity supply company.)
I checked in an electrical store here,
and the ceiling roses sold now are as shown in the online texts.

Any advice on this setup gratefully received.

It sounds like you are going to have to be a bit methodical and do some
detective work. Look in a couple of roses and see if they are the same.
Same goes for a couple of switches, see if we can figure out how this
all hangs together.

But I'm tending to the advice offered by several posters
to get a temporary battery-operated light for the bathroom,
probably from B&Q.

I would not be inclined to go patching anything together with outer
circuits until you are *sure* you know how it is currently wired,
otherwise there may be any number of unpredictable and possibly
dangerous outcomes.


--
Cheers,

John.

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

Its on a different circuit. cannot you simply get a portable led chargeable
light and shove it in there for the period.

The most common fault condition from memory is cooking of the connections in
the rose and some kind of lack of continuity caused this way, after all,
wire hardly ever fails, its normally connections that get dirty, fall to
bits etc, unless you have mice in which case look for decomposing
electrocuted mice!

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Timothy Murphy" wrote in message
...
Several (but not all) lights on one lighting circuit in my house
have stopped working.
I asked on this newsgroup about the problem,
and received many useful suggestions,
particularly pointers to the circuit diagrams at
http://wiki.diyfaq.org.uk/index.php?...ers#Overvie w
and
http://wiki.diyfaq.org.uk/index.php?...ers#Lightin g

I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.
Unfortunately replacing the connection seems to require
a lot of work - either removing some of the wooden ceiling
between the 2 lights (about 4 metres apart)
or pulling up the carpet in the room above,
and removing some of the floor-boards.

We have visitors staying next week,
and one of the rooms with no light is the bathroom,
so I am thinking of effecting a temporary kludge.

What I am thinking of doing is removing the ceiling rose
on one of the affected lights,
and adding a temporary connection to a power socket.

Is this a dangerous experiment?

--
Timothy Murphy
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland

Not so much wired as weird.

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Grimly Curmudgeon" wrote in message
...
On Sat, 8 Oct 2011 15:29:39 +0000 (UTC), Jules Richardson
wrote:

Then if it is a bathroom ... that is a non-no

Was that a typo? A non-no would be a yes, a no-no would be a no. ;-)

If it's a bathroom, I suspect he's poo-pooed the idea.

Timothy Murphy wrote:

Each ceiling rose has two terminals on the ceiling side,
one of which has 3 incoming wires attached to it,
and the other has 1 incoming wire attached to it.
The two wires to the light are attached to the two terminals
underneath the rose.

Doeesn't sound like the junction-box wiring scheme, so likely to be
loop-in scheme, but your description of two terminals each with three
wires doesn't sound right, unless one is a short wire linking terminals
within the rose?

What would be normal ...

One of the terminals with three wires (red?) are the permanent lives,
one in from the upstream rose, one out to the downstream rose, and one
to the switch.

The neutral terminal should have two (black?) wires, one in from from
the upstream rose, one out to the downstream rose, and also a (blue?)
wire going to the bulb (possibly a link to the underneath terminal?)

The other wire (black with red sleeve?) coming back from the switch
should go to the bulb (or possibly another link to the other underneath
terminal?)

Depending on age, you may also have an earth terminal (green/yellow?)
with connections from downstream, to upstream an to the switch.

Though if you're not looking at a rose in-between two other roses, or if
you have some unusual two/three way switching it might not be as
described. Also that would be the UK norm, not sure of Irish differences.

A photo would probably clarify ... but not directly solve your problem.

Timothy Murphy wrote:
Bill wrote:

I've worked out that there must be a break in the connection
between 2 of the lights on this circuit.

Did you work this out in theory or have you actually been into the
fittings and tested?

Thanks for your (and all the other) responses.
This was in fact a purely theoretical deduction ...

If you haven't been into the fittings then it maybe as simple as a
loose screw allowing the feed to the next light to become
disconnected. Much quicker to fix than your proposed temporary
solution. Also rather a lot safer :-)

I've looked at all the ceiling roses that are affected,
particularly the last one working and the first one affected.
The connections on them all look fine to me.

If course the problem could be at a working light fitting!

Unfortunately for my experiment,
the ceiling roses are not as in the online diagram at
http://wiki.diyfaq.org.uk/index.php?...ers#Lightin g
and elsewhere online.
Each ceiling rose has two terminals on the ceiling side,
one of which has 3 incoming wires attached to it,
and the other has 1 incoming wire attached to it.
The two wires to the light are attached to the two terminals
underneath the rose.

Is the ceiling rose similar to?

http://www.tlc-direct.co.uk/Products/ASPCR2000.html

The only way I can make sense of this is that the single wire
goes to the switch and thence to the live supply,
while the 3 wires are negative and go to the next light,
the last light and possibly the switch?

Does every fitting have 3 neutrals?

I should say the wiring is fairly old - 25 years -
but was installed by an electrician who I am sure
would have followed whatever rules were in place at the time.
(He worked for the electricity supply company.)
I checked in an electrical store here,
and the ceiling roses sold now are as shown in the online texts.

Any advice on this setup gratefully received.

You need a voltstick
http://www.tlc-direct.co.uk/Products/TMPL107.html
to help trace the problem

--
Adam

In message , John
Rumm writes
On 08/10/2011 16:40, Jules Richardson wrote:

Do you think that the cable has just broken somewhere along its length
for some reason - or do you mean there's a hidden junction box somewhere
with a faulty connection? (over here junction boxes have to always be
accessible, but I don't recall if that was a UK requirement)

Same rule applies here - any screw terminal connection must remain
accessible.


Isn't that a relatively recent requirement though?

And anyway, I'd not trust a sparks to still ignore it.

Last year we had a new wood conservatory installed. Electrician (used by
the conservatory company) came to do a little bit of wiring for the
electric roof vent openers. Behind what would eventually be boxed in and
pretty inaccessible (screwed in place, but holes filled etc.

He was happily wiring up the connections with choc blocks, until I
pointed out the error of his ways
--
Chris French

On 09/10/2011 15:27, chris French wrote:
In message , John
Rumm writes
On 08/10/2011 16:40, Jules Richardson wrote:

Do you think that the cable has just broken somewhere along its length
for some reason - or do you mean there's a hidden junction box somewhere
with a faulty connection? (over here junction boxes have to always be
accessible, but I don't recall if that was a UK requirement)

Same rule applies here - any screw terminal connection must remain
accessible.


Isn't that a relatively recent requirement though?

not that recent... don't know when it came in, but before the 16th edition.

And anyway, I'd not trust a sparks to still ignore it.

Well yes, that is possible. Also the definition of "accessible" varies a
bit. Some would count under a floor with liftable boards as accessible.

(Although not the plastered over 5A junction box I found just above the
sink in the previous neighbours house... connected to a 30A fuse by a
length of 1mm^2 flex, thence feeding some sockets in the kitchen ;-))

Last year we had a new wood conservatory installed. Electrician (used by
the conservatory company) came to do a little bit of wiring for the
electric roof vent openers. Behind what would eventually be boxed in and
pretty inaccessible (screwed in place, but holes filled etc.

He was happily wiring up the connections with choc blocks, until I
pointed out the error of his ways

To be fair there are chock blocks and chock blocks. Some are so crap you
can never get the screw tight enough to make a gas tight connection,
others are somewhat better. Chances are the better ones are unlikely to
cause any problem on a low current application like that.


--
Cheers,

John.

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| John Rumm - john(at)internode(dot)co(dot)uk |
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On Sun, 09 Oct 2011 01:07:51 +0100, Timothy Murphy wrote:

Bill wrote:

I've worked out that there must be a break in the connection between 2
of the lights on this circuit.

Did you work this out in theory or have you actually been into the
fittings and tested?

Thanks for your (and all the other) responses. This was in fact a purely
theoretical deduction ...

If you haven't been into the fittings then it maybe as simple as a
loose screw allowing the feed to the next light to become disconnected.
Much quicker to fix than your proposed temporary solution. Also
rather a lot safer :-)

I've looked at all the ceiling roses that are affected, particularly the
last one working and the first one affected. The connections on them all
look fine to me.

Unfortunately for my experiment,
the ceiling roses are not as in the online diagram at
http://wiki.diyfaq.org.uk/index.php?
title=House_Wiring_for_Beginners#Lighting
and elsewhere online.
Each ceiling rose has two terminals on the ceiling side, one of which
has 3 incoming wires attached to it, and the other has 1 incoming wire
attached to it. The two wires to the light are attached to the two
terminals underneath the rose.

The only way I can make sense of this is that the single wire goes to
the switch and thence to the live supply, while the 3 wires are negative
and go to the next light, the last light and possibly the switch?

Unscrew the switch covers and see what you've got there.

From your description, it sounds like the single wire must be switched,
and that maybe someone's split the lives and neutrals so that one side
goes direct to the ceiling fitting and the other goes direct to the
switches. That sounds unconventional at best!

The other possibility I can think of is that there's a hidden junction
box somewhere close to the light fitting which carries the 'missing'
wires:


CEILING FITTING JUNCTION BOX

+---- N out +---- L out
| |
N in ----A---- N out L in ----E---- L out
| |
| B-----------+ F---------------+
| | | [SW]
C D +------------G---------------+
| |
o o
[bulb]


.... hopefully that displays OK :-)

That setup would give you a switched live for the light fitting, and two
L/N pairs going off to 'downstream' fittings - I just don't know why
anyone would wire it like that rather than doing it all in the ceiling
fitting.

At the first non-working light, a disconnect of either the neutral-in at
the ceiling fitting or the live-in at the 'hidden' junction box would
give a single failure point and knock out that light and any ones
downstream of it.

cheers

Jules