I was thinking about replacing a lightswitch but when I looked behind
there are three red wires - one joined to one terminal and two joined
to the other. There is also a black wire that just seems to be passing
through. This is a bedroom with one light and one switch. I always
thought the live travelled from the ceiling to the switch and back
again and the neutral stayed in the ceiling. Any wisdom?

On 29/03/2024 18:31, Scott wrote:

> I was thinking about replacing a lightswitch but when I looked behind
> there are three red wires - one joined to one terminal and two joined
> to the other. There is also a black wire that just seems to be passing
> through. This is a bedroom with one light and one switch. I always
> thought the live travelled from the ceiling to the switch and back
> again and the neutral stayed in the ceiling. Any wisdom?

Almost sounds like loop through the switch wiring

<http://wiki.diyfaq.org.uk/index.php/House_Wiring_for_Beginners#Lighting>

but if there are 3x red, you'd expect 3x black too, or something funky
is going on ... photo(s)?

On 29/03/2024 18:31, Scott wrote:
> I was thinking about replacing a lightswitch but when I looked behind
> there are three red wires - one joined to one terminal and two joined
> to the other. There is also a black wire that just seems to be passing
> through. This is a bedroom with one light and one switch. I always
> thought the live travelled from the ceiling to the switch and back
> again and the neutral stayed in the ceiling. Any wisdom?

These days with smart switches etc. the neutral is often routed to the
switch back box so that the switch can get live and neutral for power.

See 2 plate method.
https://www.youtube.com/watch?v=1G4fW2DeqPA

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Fri, 29 Mar 2024 18:43:44 +0000, Andy Burns <usenet@andyburns.uk>
wrote:

>On 29/03/2024 18:31, Scott wrote:
>
>> I was thinking about replacing a lightswitch but when I looked behind
>> there are three red wires - one joined to one terminal and two joined
>> to the other. There is also a black wire that just seems to be passing
>> through. This is a bedroom with one light and one switch. I always
>> thought the live travelled from the ceiling to the switch and back
>> again and the neutral stayed in the ceiling. Any wisdom?
>
>Almost sounds like loop through the switch wiring
>
><http://wiki.diyfaq.org.uk/index.php/House_Wiring_for_Beginners#Lighting>
>
>but if there are 3x red, you'd expect 3x black too, or something funky
>is going on ... photo(s)?

I'll try and get a photo in daylight. There are other peculiarites
(such as two switches that do not seem to do anything). I am trying to
organise a full inspection and wiring check.

On Fri, 29 Mar 2024 18:59:30 +0000, alan_m <junk@admac.myzen.co.uk>
wrote:

>On 29/03/2024 18:31, Scott wrote:
>> I was thinking about replacing a lightswitch but when I looked behind
>> there are three red wires - one joined to one terminal and two joined
>> to the other. There is also a black wire that just seems to be passing
>> through. This is a bedroom with one light and one switch. I always
>> thought the live travelled from the ceiling to the switch and back
>> again and the neutral stayed in the ceiling. Any wisdom?
>
>These days with smart switches etc. the neutral is often routed to the
>switch back box so that the switch can get live and neutral for power.
>
>See 2 plate method.
>https://www.youtube.com/watch?v=1G4fW2DeqPA

I think the fact that the wires are red and black rules out this
possibility.

On 29/03/2024 19:48, Scott wrote:
> On Fri, 29 Mar 2024 18:59:30 +0000, alan_m <junk@admac.myzen.co.uk>
> wrote:
>
>> On 29/03/2024 18:31, Scott wrote:
>>> I was thinking about replacing a lightswitch but when I looked behind
>>> there are three red wires - one joined to one terminal and two joined
>>> to the other. There is also a black wire that just seems to be passing
>>> through. This is a bedroom with one light and one switch. I always
>>> thought the live travelled from the ceiling to the switch and back
>>> again and the neutral stayed in the ceiling. Any wisdom?
>>
>> These days with smart switches etc. the neutral is often routed to the
>> switch back box so that the switch can get live and neutral for power.
>>
>> See 2 plate method.
>> https://www.youtube.com/watch?v=1G4fW2DeqPA
>
> I think the fact that the wires are red and black rules out this
> possibility.

Could at one time been a ceiling pull cord switch above a bed with
either the wall switch or the ceiling switch being able to turn on/off
the light. If the ceiling switch has been removed the wall switch
wiring may have been modified (without removing any wires).

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 29/03/2024 18:31, Scott wrote:
> I was thinking about replacing a lightswitch but when I looked behind
> there are three red wires - one joined to one terminal and two joined
> to the other. There is also a black wire that just seems to be passing
> through. This is a bedroom with one light and one switch. I always
> thought the live travelled from the ceiling to the switch and back
> again and the neutral stayed in the ceiling. Any wisdom?

I have wiring behind a light switch like that.

It's a convenient route to get power for lighting from one floor to the
next.

On Fri, 29 Mar 2024 20:04:56 +0000, alan_m <junk@admac.myzen.co.uk>
wrote:

>On 29/03/2024 19:48, Scott wrote:
>> On Fri, 29 Mar 2024 18:59:30 +0000, alan_m <junk@admac.myzen.co.uk>
>> wrote:
>>
>>> On 29/03/2024 18:31, Scott wrote:
>>>> I was thinking about replacing a lightswitch but when I looked behind
>>>> there are three red wires - one joined to one terminal and two joined
>>>> to the other. There is also a black wire that just seems to be passing
>>>> through. This is a bedroom with one light and one switch. I always
>>>> thought the live travelled from the ceiling to the switch and back
>>>> again and the neutral stayed in the ceiling. Any wisdom?
>>>
>>> These days with smart switches etc. the neutral is often routed to the
>>> switch back box so that the switch can get live and neutral for power.
>>>
>>> See 2 plate method.
>>> https://www.youtube.com/watch?v=1G4fW2DeqPA
>>
>> I think the fact that the wires are red and black rules out this
>> possibility.
>
>Could at one time been a ceiling pull cord switch above a bed with
>either the wall switch or the ceiling switch being able to turn on/off
>the light. If the ceiling switch has been removed the wall switch
>wiring may have been modified (without removing any wires).

That is an interesting suggestion. I'll ask the electrician to check
it out. I am hoping he does not find any VIR cable as this is
apparently bad news.

On Fri, 29 Mar 2024 20:06:13 +0000, Fredxx <fredxx@spam.invalid>
wrote:

>On 29/03/2024 18:31, Scott wrote:
>> I was thinking about replacing a lightswitch but when I looked behind
>> there are three red wires - one joined to one terminal and two joined
>> to the other. There is also a black wire that just seems to be passing
>> through. This is a bedroom with one light and one switch. I always
>> thought the live travelled from the ceiling to the switch and back
>> again and the neutral stayed in the ceiling. Any wisdom?
>
>I have wiring behind a light switch like that.
>
>It's a convenient route to get power for lighting from one floor to the
>next.

That's interesting too. I shall could check the breakers in daylight.

On 29/03/2024 18:31, Scott wrote:
> I was thinking about replacing a lightswitch but when I looked behind
> there are three red wires - one joined to one terminal and two joined
> to the other. There is also a black wire that just seems to be passing
> through. This is a bedroom with one light and one switch. I always
> thought the live travelled from the ceiling to the switch and back
> again and the neutral stayed in the ceiling. Any wisdom?

When replacing it swap one wire at a time so each wire is connected in
the same place it was (this assumes like for like replacement of the
switch).
Although this is a DIY group. if totally uncertain how to proceed
get an electrician in, IME electricity is not to be Shpxrq(ROT 13) with

On Sat, 30 Mar 2024 09:31:23 +0000, Soup <cheez2011@gmail.com> wrote:

>On 29/03/2024 18:31, Scott wrote:
>> I was thinking about replacing a lightswitch but when I looked behind
>> there are three red wires - one joined to one terminal and two joined
>> to the other. There is also a black wire that just seems to be passing
>> through. This is a bedroom with one light and one switch. I always
>> thought the live travelled from the ceiling to the switch and back
>> again and the neutral stayed in the ceiling. Any wisdom?
>
>
>When replacing it swap one wire at a time so each wire is connected in
>the same place it was (this assumes like for like replacement of the
>switch).
> Although this is a DIY group. if totally uncertain how to proceed
>get an electrician in, IME electricity is not to be Shpxrq(ROT 13) with

I very much agree with your latter point. I am arranging for an
electrician to carry out a wiring check. I probably want a new RCBO
equipped consumer unit (at my last flat at one time the computer
crashed out when the washing machine started the spin cycle).

On Fri, 29 Mar 2024 21:15:48 +0000, Scott
<newsgroups@gefion.myzen.co.uk> wrote:

>On Fri, 29 Mar 2024 20:06:13 +0000, Fredxx <fredxx@spam.invalid>
>wrote:
>
>>On 29/03/2024 18:31, Scott wrote:
>>> I was thinking about replacing a lightswitch but when I looked behind
>>> there are three red wires - one joined to one terminal and two joined
>>> to the other. There is also a black wire that just seems to be passing
>>> through. This is a bedroom with one light and one switch. I always
>>> thought the live travelled from the ceiling to the switch and back
>>> again and the neutral stayed in the ceiling. Any wisdom?
>>
>>I have wiring behind a light switch like that.
>>
>>It's a convenient route to get power for lighting from one floor to the
>>next.
>
>That's interesting too. I shall could check the breakers in daylight.

I have looked. The upstairs and downstairs lights are on separate
circuits.

On 30/03/2024 10:10, Scott wrote:
> On Sat, 30 Mar 2024 09:31:23 +0000, Soup <cheez2011@gmail.com> wrote:
>
>> On 29/03/2024 18:31, Scott wrote:
>>> I was thinking about replacing a lightswitch but when I looked behind
>>> there are three red wires - one joined to one terminal and two joined
>>> to the other. There is also a black wire that just seems to be passing
>>> through. This is a bedroom with one light and one switch. I always
>>> thought the live travelled from the ceiling to the switch and back
>>> again and the neutral stayed in the ceiling. Any wisdom?
>>
>>
>> When replacing it swap one wire at a time so each wire is connected in
>> the same place it was (this assumes like for like replacement of the
>> switch).
>> Although this is a DIY group. if totally uncertain how to proceed
>> get an electrician in, IME electricity is not to be Shpxrq(ROT 13) with
>
> I very much agree with your latter point. I am arranging for an
> electrician to carry out a wiring check. I probably want a new RCBO
> equipped consumer unit (at my last flat at one time the computer
> crashed out when the washing machine started the spin cycle).

ME:- Got a belt from an old Dancette record player I was faffing with
(was only eight or so) I hadn't unplugged it from the wall (didn't know
any better).
Was sticking my hands and various tools into its innards when B L A M
240 Volts up one finger and down the next(if it had been across the
heart don't think I would still be here). Even 'only' across my fingers
still managed to throw (or rather it energised my muscles and I threw
myself) me across the room.
Took me the rest of the day to stop crying and shaking. Have been
wary of electricity ever since.
E.G. Turn the whole house off rather than a specific circuit or at the
very least check, check and check again that any circuit I am working on
is actually dead.

On 30/03/2024 10:54, Soup wrote:
> On 30/03/2024 10:10, Scott wrote:
>> On Sat, 30 Mar 2024 09:31:23 +0000, Soup <cheez2011@gmail.com> wrote:
>>
>>> On 29/03/2024 18:31, Scott wrote:
>>>> I was thinking about replacing a lightswitch but when I looked behind
>>>> there are three red wires - one joined to one terminal and two joined
>>>> to the other. There is also a black wire that just seems to be passing
>>>> through. This is a bedroom with one light and one switch. I always
>>>> thought the live travelled from the ceiling to the switch and back
>>>> again and the neutral stayed in the ceiling. Any wisdom?
>>>
>>>
>>> When replacing it swap one wire at a time so each wire is connected in
>>> the same place it was (this assumes like for like replacement of the
>>> switch).
>>>    Although this is a DIY group. if totally uncertain  how to proceed
>>> get an electrician in, IME electricity is not to be Shpxrq(ROT 13) with
>>
>> I very much agree with your latter point. I am arranging for an
>> electrician to carry out a wiring check. I probably want a new RCBO
>> equipped consumer unit (at my last flat at one time the computer
>> crashed out when the washing machine started the spin cycle).
>
> ME:- Got a belt from an old Dancette record player I was faffing with
> (was only eight or so) I hadn't unplugged it from the wall (didn't know
> any better).

I got caught out by a reel-to-reel tape recorder - unexpectedly, the
erase head was mains powered.

On 30/03/2024 17:31, SteveW wrote:
> On 30/03/2024 10:54, Soup wrote:
>> On 30/03/2024 10:10, Scott wrote:
>>> On Sat, 30 Mar 2024 09:31:23 +0000, Soup <cheez2011@gmail.com> wrote:
>>>
>>>> On 29/03/2024 18:31, Scott wrote:
>> ME:- Got a belt from an old Dancette record player I was faffing with
>> (was only eight or so) I hadn't unplugged it from the wall (didn't
>> know any better).
>
> I got caught out by a reel-to-reel tape recorder - unexpectedly, the
> erase head was mains powered.

I got a belt from a reel-to-reel tape recorder as child. I forgot that
even when the main switch on the tape recorder was in the "off"
position, there was still power to the input terminals on that switch! I
still have the two marks on my finger that happened to brush the live
and neutral where the wires were soldered to the switch contacts.

I also got a belt much more recently from a GU10 light fitting. I was
gradually changing the fittings in a room that has a grid of GU10s in
the ceiling. I'd been really good about turning off at least the wall
switch and ideally the MCB in the fuse box. I'd finished for the day,
then my wife said "Can you do that one as well". The crucial thing is
that the lightbulbs were Philips Hue - these can be turned off within
the bulb housing (via a smartphone app) so it is possible for the bulb
to be off even when there is mains to it. Guess which idiot forgot that
and assumed "no light" means "switch is off at the wall". The shock was
the mildest mains shock I've ever had, probably because the RCD tripped
within the stated 30 msec; all previous shocks were in the days before
RCDs so the power just carried on until I ripped my hand away.

On 29/03/2024 18:31, Scott wrote:
> I was thinking about replacing a lightswitch but when I looked behind
> there are three red wires - one joined to one terminal and two joined
> to the other. There is also a black wire that just seems to be passing
> through. This is a bedroom with one light and one switch. I always
> thought the live travelled from the ceiling to the switch and back
> again and the neutral stayed in the ceiling. Any wisdom?

Could be "loop through switch" style wiring:

https://wiki.diyfaq.org.uk/index.php/House_Wiring_for_Beginners#Other_Wiring_Options

--
Cheers,

John.

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

On 30/03/2024 10:11, Scott wrote:
> On Fri, 29 Mar 2024 21:15:48 +0000, Scott
> <newsgroups@gefion.myzen.co.uk> wrote:
>
>> On Fri, 29 Mar 2024 20:06:13 +0000, Fredxx <fredxx@spam.invalid>
>> wrote:
>>
>>> On 29/03/2024 18:31, Scott wrote:
>>>> I was thinking about replacing a lightswitch but when I looked behind
>>>> there are three red wires - one joined to one terminal and two joined
>>>> to the other. There is also a black wire that just seems to be passing
>>>> through. This is a bedroom with one light and one switch. I always
>>>> thought the live travelled from the ceiling to the switch and back
>>>> again and the neutral stayed in the ceiling. Any wisdom?
>>>
>>> I have wiring behind a light switch like that.
>>>
>>> It's a convenient route to get power for lighting from one floor to the
>>> next.
>>
>> That's interesting too. I shall could check the breakers in daylight.
>
> I have looked. The upstairs and downstairs lights are on separate
> circuits.

So are mine.

The point I was making is that power to my upstairs lighting circuit is
routed via a switch from the floor to the ceiling.

The conductors run behind the switch, except the live feed is teed off
to the switch and a single continues up the wall and along the ceiling
to the rose.

On Sun, 31 Mar 2024 21:13:54 +0100, Fredxx <fredxx@spam.invalid>
wrote:

>On 30/03/2024 10:11, Scott wrote:
>> On Fri, 29 Mar 2024 21:15:48 +0000, Scott
>> <newsgroups@gefion.myzen.co.uk> wrote:
>>
>>> On Fri, 29 Mar 2024 20:06:13 +0000, Fredxx <fredxx@spam.invalid>
>>> wrote:
>>>
>>>> On 29/03/2024 18:31, Scott wrote:
>>>>> I was thinking about replacing a lightswitch but when I looked behind
>>>>> there are three red wires - one joined to one terminal and two joined
>>>>> to the other. There is also a black wire that just seems to be passing
>>>>> through. This is a bedroom with one light and one switch. I always
>>>>> thought the live travelled from the ceiling to the switch and back
>>>>> again and the neutral stayed in the ceiling. Any wisdom?
>>>>
>>>> I have wiring behind a light switch like that.
>>>>
>>>> It's a convenient route to get power for lighting from one floor to the
>>>> next.
>>>
>>> That's interesting too. I shall could check the breakers in daylight.
>>
>> I have looked. The upstairs and downstairs lights are on separate
>> circuits.
>
>So are mine.
>
>The point I was making is that power to my upstairs lighting circuit is
>routed via a switch from the floor to the ceiling.
>
>The conductors run behind the switch, except the live feed is teed off
>to the switch and a single continues up the wall and along the ceiling
>to the rose.

Okay, thanks. I get it now. My conclusion is that I want a proper
electrician to check the wiring and consumer unit and to make
appropriate recommendations.