Round 2, the endoscope has arrived!

I have removed the light fitting in the kitchen and it has a chocolate
block connector behind it presumably performing the function of a ceiling
rose in connecting the lighting ring. The three spotlights are marked 240
v so presumably no transformer.

I have a live indication from a neon on the red cable and 66 volts across
red and black when it is on, 0 when off (it's two way lighting).

There is an outdoor light as well (which also doesn't work) and a double
gang switch by the back door, one for the kitchen light, the other for the
outdoor light. Voltage at the connector is impacted by BOTH switches, that
seems odd and I need to get my head round it.

I poked the endoscope up the hole where the chocolate block is and I can
see white cables, fibre glass and the underside of the chipboard. I am
having a bit of an issue orienting myself so I can understand what I can
see.

I'm having a cup of tea while I think this through, particularly 66
volts....

--
Jeff Gaines Dorset UK
The facts, although interesting, are irrelevant

Jeff Gaines wrote:

> I'm having a cup of tea while I think this through, particularly 66
> volts....

I can't remember if you said what type of meter you're measuring with?

Does one of the black wires have red sleeving?

I'd start by turning off power, mark all cables entering the chocblock,
photograph it with the marks so you're sure you can put it back exactly
as is, post us a link, separate all wires from the cables, temporarily
terminate each wire into e.g. another length of chocblock with no
connection between wires, measure voltage between red/black on each cable.

On 30/07/2023 in message <kimpsjFikk5U2@mid.individual.net> Andy Burns
wrote:

>Jeff Gaines wrote:
>
>>I'm having a cup of tea while I think this through, particularly 66
>>volts....
>
>I can't remember if you said what type of meter you're measuring with?
>
>Does one of the black wires have red sleeving?
>
>I'd start by turning off power, mark all cables entering the chocblock,
>photograph it with the marks so you're sure you can put it back exactly as
>is, post us a link, separate all wires from the cables, temporarily
>terminate each wire into e.g. another length of chocblock with no
>connection between wires, measure voltage between red/black on each cable.

Thanks Andy :-)

Will separate the block as next step.

In the meantime I looked at the outside light which fell apart in my
hands. All the innards are now in the bin and I have connected the cables
to a 20 Amp choc block and sealed the cover back on for now.

Not sure the meter has a known make but it's digital, could be 20 years
old and reads 240 v when testing via my horribly hazardous plug, trailing
lead and choc block setup!

--
Jeff Gaines Dorset UK
Though no-one can go back and make a new start, everyone can start from
now and make a new ending.

Sounds like some are in series?
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Jeff Gaines" <jgnewsid@outlook.com> wrote in message
news:xn0o4ybhz76lxqd00q@news.individual.net...
>
> Round 2, the endoscope has arrived!
>
> I have removed the light fitting in the kitchen and it has a chocolate
> block connector behind it presumably performing the function of a ceiling
> rose in connecting the lighting ring. The three spotlights are marked 240
> v so presumably no transformer.
>
> I have a live indication from a neon on the red cable and 66 volts across
> red and black when it is on, 0 when off (it's two way lighting).
>
> There is an outdoor light as well (which also doesn't work) and a double
> gang switch by the back door, one for the kitchen light, the other for the
> outdoor light. Voltage at the connector is impacted by BOTH switches, that
> seems odd and I need to get my head round it.
>
> I poked the endoscope up the hole where the chocolate block is and I can
> see white cables, fibre glass and the underside of the chipboard. I am
> having a bit of an issue orienting myself so I can understand what I can
> see.
>
> I'm having a cup of tea while I think this through, particularly 66
> volts....
>
> --
> Jeff Gaines Dorset UK
> The facts, although interesting, are irrelevant

On 30/07/2023 13:23, Jeff Gaines wrote:
> On 30/07/2023 in message <kimpsjFikk5U2@mid.individual.net> Andy Burns
> wrote:
>
>> Jeff Gaines wrote:
>>
>>> I'm having a cup of tea while I think this through, particularly 66
>>> volts....
>>
>> I can't remember if you said what type of meter you're measuring with?
>>
>> Does one of the black wires have red sleeving?
>>
>> I'd start by turning off power, mark all cables entering the
>> chocblock, photograph it with the marks so you're sure you can put it
>> back exactly as is, post us a link, separate all wires from the
>> cables, temporarily terminate each wire into e.g. another length of
>> chocblock with no connection between wires, measure voltage between
>> red/black on each cable.
>
> Thanks Andy :-)
>
> Will separate the block as next step.
>
> In the meantime I looked at the outside light which fell apart in my
> hands. All the innards are now in the bin and I have connected the
> cables to a 20 Amp choc block and sealed the cover back on for now.
>
> Not sure the meter has a known make but it's digital, could be 20 years
> old and reads 240 v when testing via my horribly hazardous plug,
> trailing lead and choc block setup!
>
Until further info I suspect the apparent 66 volts is being induced on
an open circuit wire. I would put a load on it (a bulb is simplest) and
then measure the voltage - which I expect would be zero.

On 30/07/2023 13:23, Jeff Gaines wrote:
> On 30/07/2023 in message <kimpsjFikk5U2@mid.individual.net> Andy Burns
> wrote:
>
>> Jeff Gaines wrote:
>>
>>> I'm having a cup of tea while I think this through, particularly 66
>>> volts....
>>
>> I can't remember if you said what type of meter you're measuring with?
>>
>> Does one of the black wires have red sleeving?
>>
>> I'd start by turning off power, mark all cables entering the
>> chocblock, photograph it with the marks so you're sure you can put it
>> back exactly as is, post us a link, separate all wires from the
>> cables, temporarily terminate each wire into e.g. another length of
>> chocblock with no connection between wires, measure voltage between
>> red/black on each cable.
>
> Thanks Andy :-)
>
> Will separate the block as next step.
>
> In the meantime I looked at the outside light which fell apart in my
> hands. All the innards are now in the bin and I have connected the
> cables to a 20 Amp choc block and sealed the cover back on for now.
>
> Not sure the meter has a known make but it's digital, could be 20 years
> old and reads 240 v when testing via my horribly hazardous plug,
> trailing lead and choc block setup!

Digital meters present a very high impedance when testing voltage (i.e.
the look like a very very high resistance load that draws only micro
amps of current). In most cases this is a "good thing" - it means the
meter has very little effect on the thing is is measuring. However in
this case even a disconnected wire that runs close to another live wire
will likely look "live" when measured just because it has an induced
voltage on it, and the meter will see that due to the lack of load.

(Some DMMs designed with mains voltage measurements in mind (like the
Fluke 117) have a low Z mode that deliberately introduces a small amount
of load to the circuit under test to suppress any phantom voltage readings)

--
Cheers,

John.

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

On 30/07/2023 10:21, Jeff Gaines wrote:
>
> Round 2, the endoscope has arrived!
>
> I have removed the light fitting in the kitchen and it has a chocolate
> block connector behind it presumably performing the function of a
> ceiling rose in connecting the lighting ring. The three spotlights are
> marked 240 v so presumably no transformer.
>
> I have a live indication from a neon on the red cable and 66 volts
> across red and black when it is on, 0 when off (it's two way lighting).

See my comment elsewhere in the thread.... Did you say that there was a
two way switching arrangement on one of the lights? (If so then it is
common to get a false voltage reading on one of the floating wires in
the 3&E cable due to a long run in close proximity to other live wires
in the same cable)

> There is an outdoor light as well (which also doesn't work) and a double
> gang switch by the back door, one for the kitchen light, the other for
> the outdoor light. Voltage at the connector is impacted by BOTH
> switches, that seems odd and I need to get my head round it.

If you can get to all the wire ends then you could simply disconnect all
of the terminations at the lamps (leaving those at the switches alone
other that to check their terminations are tight). Them re-make them all
from scratch, testing as you go. That way you can also sleeve wires
appropriately as you go, so you have a better chance next time!

e.g.

With all the wires disconnected, it should be easy to find the one live
set that is delivering power - so now you know which is the supply.

Your DMM on resistance/continuity mode will let you identify the switch
wires as you toggle the switch.

Link wires between fittings you can identify by shorting L&N at one
end, and testing for continuity at the other.

>
> I poked the endoscope up the hole where the chocolate block is and I can
> see white cables, fibre glass and the underside of the chipboard. I am
> having a bit of an issue orienting myself so I can understand what I can
> see.

Yup a common problem with endoscopes IME!

> I'm having a cup of tea while I think this through, particularly 66
> volts....

--
Cheers,

John.

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

On Sunday, 30 July 2023 at 10:21:52 UTC+1, Jeff Gaines wrote:
> Round 2, the endoscope has arrived!
>
> I have removed the light fitting in the kitchen and it has a chocolate
> block connector behind it presumably performing the function of a ceiling
> rose in connecting the lighting ring. The three spotlights are marked 240
> v so presumably no transformer.
>
> I have a live indication from a neon on the red cable and 66 volts across
> red and black when it is on, 0 when off (it's two way lighting).
>
> There is an outdoor light as well (which also doesn't work) and a double
> gang switch by the back door, one for the kitchen light, the other for the
> outdoor light. Voltage at the connector is impacted by BOTH switches, that
> seems odd and I need to get my head round it.
>
> I poked the endoscope up the hole where the chocolate block is and I can
> see white cables, fibre glass and the underside of the chipboard. I am
> having a bit of an issue orienting myself so I can understand what I can
> see.
>
> I'm having a cup of tea while I think this through, particularly 66
> volts....

means the cable's not connected to anything.

Depends how high impedance the meter is though. If shoving say a 100K
resistor across the probes changes the 66v, then its either inductive or
electrostatic pick up.
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Animal" <tabbypurr@gmail.com> wrote in message
news:9687ddf8-1122-413a-8921-e087724201e9n@googlegroups.com...
> On Sunday, 30 July 2023 at 10:21:52 UTC+1, Jeff Gaines wrote:
>> Round 2, the endoscope has arrived!
>>
>> I have removed the light fitting in the kitchen and it has a chocolate
>> block connector behind it presumably performing the function of a ceiling
>> rose in connecting the lighting ring. The three spotlights are marked 240
>> v so presumably no transformer.
>>
>> I have a live indication from a neon on the red cable and 66 volts across
>> red and black when it is on, 0 when off (it's two way lighting).
>>
>> There is an outdoor light as well (which also doesn't work) and a double
>> gang switch by the back door, one for the kitchen light, the other for
>> the
>> outdoor light. Voltage at the connector is impacted by BOTH switches,
>> that
>> seems odd and I need to get my head round it.
>>
>> I poked the endoscope up the hole where the chocolate block is and I can
>> see white cables, fibre glass and the underside of the chipboard. I am
>> having a bit of an issue orienting myself so I can understand what I can
>> see.
>>
>> I'm having a cup of tea while I think this through, particularly 66
>> volts....
>
> means the cable's not connected to anything.

On Monday, 31 July 2023 at 09:06:21 UTC+1, Brian Gaff wrote:

> "Animal" <tabb...@gmail.com> wrote in message
> news:9687ddf8-1122-413a...@googlegroups.com...
> > On Sunday, 30 July 2023 at 10:21:52 UTC+1, Jeff Gaines wrote:
> >> Round 2, the endoscope has arrived!
> >>
> >> I have removed the light fitting in the kitchen and it has a chocolate
> >> block connector behind it presumably performing the function of a ceiling
> >> rose in connecting the lighting ring. The three spotlights are marked 240
> >> v so presumably no transformer.
> >>
> >> I have a live indication from a neon on the red cable and 66 volts across
> >> red and black when it is on, 0 when off (it's two way lighting).
> >>
> >> There is an outdoor light as well (which also doesn't work) and a double
> >> gang switch by the back door, one for the kitchen light, the other for
> >> the
> >> outdoor light. Voltage at the connector is impacted by BOTH switches,
> >> that
> >> seems odd and I need to get my head round it.
> >>
> >> I poked the endoscope up the hole where the chocolate block is and I can
> >> see white cables, fibre glass and the underside of the chipboard. I am
> >> having a bit of an issue orienting myself so I can understand what I can
> >> see.
> >>
> >> I'm having a cup of tea while I think this through, particularly 66
> >> volts....
> >
> > means the cable's not connected to anything.

> Depends how high impedance the meter is though. If shoving say a 100K
> resistor across the probes changes the 66v, then its either inductive or
> electrostatic pick up.
> Brian

it's a digital meter fool.