I have checked another light switch. Again no grommet.
However, this time there are five red wires and one black. Two live
wires are connected to the COM terminal on the switch with one
switched wire on L1. Two of the red wires are out of use with the ends wrapped in insulating tape (white). The black wire is connected to the earthing terminal.
It seems to me there should definitely be a grommet (though it will be
a tight fit with six wires entering), the live wires should be sleeved
in brown, there must be a better way to terminate the unused cables
and especially it is concerning that the neutral could be connected to
the earth terminal (which then connects to the screws for the the
switch). What colour should be used to sleeve a disused wire?
Can I fix it, or is it time to call in the experts? My friend (who is
a retired electrical engineer) knows more about 11kV though I expect
the general principles are the same :-)
What do the bright sparks think?
I have checked another light switch. Again no grommet.
However, this time there are five red wires and one black. Two live
wires are connected to the COM terminal on the switch with one
switched wire on L1. Two of the red wires are out of use with the ends wrapped in insulating tape (white). The black wire is connected to the earthing terminal.
It seems to me there should definitely be a grommet (though it will be
a tight fit with six wires entering), the live wires should be sleeved
in brown, there must be a better way to terminate the unused cables
and especially it is concerning that the neutral could be connected to
the earth terminal (which then connects to the screws for the the
switch).
What colour should be used to sleeve a disused wire?
Can I fix it,
or is it time to call in the experts? My friend (who is
a retired electrical engineer) knows more about 11kV though I expect
the general principles are the same :-)
What do the bright sparks think?
I have checked another light switch. Again no grommet.
However, this time there are five red wires and one black. Two live
wires are connected to the COM terminal on the switch with one
switched wire on L1. Two of the red wires are out of use with the ends wrapped in insulating tape (white). The black wire is connected to the earthing terminal.
It seems to me there should definitely be a grommet (though it will be
a tight fit with six wires entering), the live wires should be sleeved
in brown, there must be a better way to terminate the unused cables
and especially it is concerning that the neutral could be connected to
the earth terminal (which then connects to the screws for the the
switch). What colour should be used to sleeve a disused wire?
Can I fix it, or is it time to call in the experts? My friend (who is
a retired electrical engineer) knows more about 11kV though I expect
the general principles are the same :-)
What do the bright sparks think?
I am not a bright spark, but I am a very cynical one. Given the
oddities here do not assume that the black wire is a neutral.
I once; long ago, found a three phase system where somebody had used a
red black and green three core cable for the three phase conductors.
The explanation was basically that "Old George did that and he picked
up bad habits during the war".
Scott <[email protected]> wrote:
I have checked another light switch. Again no grommet.
However, this time there are five red wires and one black. Two live
wires are connected to the COM terminal on the switch with one
switched wire on L1. Two of the red wires are out of use with the ends
wrapped in insulating tape (white). The black wire is connected to the
earthing terminal.
It seems to me there should definitely be a grommet (though it will be
a tight fit with six wires entering), the live wires should be sleeved
in brown, there must be a better way to terminate the unused cables
and especially it is concerning that the neutral could be connected to
the earth terminal (which then connects to the screws for the the
switch). What colour should be used to sleeve a disused wire?
Can I fix it, or is it time to call in the experts? My friend (who is
a retired electrical engineer) knows more about 11kV though I expect
the general principles are the same :-)
What do the bright sparks think?
Likely it was originally a multiple switch plate, possibly three switches which might explain the two taped off red wires which would likely be switched lives going to multiple lights originally.
It looks like the loop in is being done at the switch instead of at the rosette, hence the two reds in COM which will be the live feed going from switch to switch. L1 will be the switched live going to the rosette/light fitting. Check the rosette you will likely find only two wires probably
done in singles the black neutral being the only wire connecting all the rosettes and the red being the switched live from the switch. Our lighting
in our 1975 bungalow was done looping in at the switches in our case all
the wires were done in singles (kind off). Red sheathed wires with a green stripe on one side entered the back box. Stripping the outer sheath
revealed a second red sheathed conductor and a bare CPC. At the rosettes
the single and earth switched live and the black neutral were present. Are you sure the black wire is actually black and not just discoloured.
As for grometting the back box some lighting 16mm deep boxes do not need a grommet as the cable entry is peined over forming a rounded edge, running your finger over it should verify that.
On Thu, 20 Mar 2025 09:56:04 +0000, Scott
<[email protected]> wrote:
I have checked another light switch. Again no grommet.
However, this time there are five red wires and one black. Two live
wires are connected to the COM terminal on the switch with one
switched wire on L1. Two of the red wires are out of use with the ends
wrapped in insulating tape (white). The black wire is connected to the
earthing terminal.
It seems to me there should definitely be a grommet (though it will be
a tight fit with six wires entering), the live wires should be sleeved
in brown, there must be a better way to terminate the unused cables
and especially it is concerning that the neutral could be connected to
the earth terminal (which then connects to the screws for the the
switch). What colour should be used to sleeve a disused wire?
Can I fix it, or is it time to call in the experts? My friend (who is
a retired electrical engineer) knows more about 11kV though I expect
the general principles are the same :-)
What do the bright sparks think?
I am not a bright spark, but I am a very cynical one. Given the
oddities here do not assume that the black wire is a neutral.
I once; long ago, found a three phase system where somebody had used a
red black and green three core cable for the three phase conductors.
The explanation was basically that "Old George did that and he picked
up bad habits during the war".
John
On 20/03/2025 09:56, Scott wrote:
I have checked another light switch. Again no grommet.
This will be very common - in fact in many older installs it would be
rare to see a grommet. It is more an issue during installation than use >unless it is on a circuit that is fully loaded to near capacity
relatively frequently (where thermal expansion might result in regular
cable movement).
However, this time there are five red wires and one black. Two live
wires are connected to the COM terminal on the switch with one
switched wire on L1. Two of the red wires are out of use with the ends
wrapped in insulating tape (white). The black wire is connected to the
earthing terminal.
It seems to me there should definitely be a grommet (though it will be
a tight fit with six wires entering), the live wires should be sleeved
in brown, there must be a better way to terminate the unused cables
You would normally only sleeve a wire when it is being used for a
purpose that conflicts with its colour. So for example, in a single "one
way" light switch you will typically have two wires *both* of which are
live - one permanent, one switched. Since this is commonly supplied with
a normal T&E cable, one should over sleeve the black/blue in Red / Brown >(depending on the colour scheme being used), to indicate the change of
use. Again however is is very common for this to be missing. For an >electrician, they may disregard the convention since it is "obvious"
that is what is going on.
Arguably if you are poking about in the back
of switches, then it should ideally also be obvious to you as well.
(The sleeving is still very handy, when there are multiple cables - say
in a ceiling rose, since it makes identifying the switch cable easy when
the rose has been disconnected. As evidenced by the number of posts we
have had here over the years along the lines of "I changed the ceiling
rose, and put all the reds together and all the backs together, and now
the circuit trips when I turn the light on")
and especially it is concerning that the neutral could be connected to
the earth terminal (which then connects to the screws for the the
switch).
Do you know if it *is* actually neutral though?
What colour should be used to sleeve a disused wire?
Depends on if it is still connected to anything. The "by the book" way
of dealing with unused wires is they should be made off in an unused >terminal, and connected to earth at at least one end. In the latter case
you could sleeve it in green/yellow.
In reality, taped over wires are common. Folded in some sleeving is also >common ( and arguably better than tape where the glue could fail over
time and it comes unwrapped).
Can I fix it,
Is it broken? Is there an immediate safety risk to users?
If not it might be better left alone.
or is it time to call in the experts? My friend (who is
a retired electrical engineer) knows more about 11kV though I expect
the general principles are the same :-)
Surprisingly there can be quite a big disparity between distribution
side, and consumer side as to what is normal and accepted.
What do the bright sparks think?
Time for tea :-)
On Thu, 20 Mar 2025 12:09:00 +0000, John Rumm
<[email protected]> wrote:
On 20/03/2025 09:56, Scott wrote:
I have checked another light switch. Again no grommet.
This will be very common - in fact in many older installs it would be
rare to see a grommet. It is more an issue during installation than use
unless it is on a circuit that is fully loaded to near capacity
relatively frequently (where thermal expansion might result in regular
cable movement).
However, this time there are five red wires and one black. Two live
wires are connected to the COM terminal on the switch with one
switched wire on L1. Two of the red wires are out of use with the ends
wrapped in insulating tape (white). The black wire is connected to the
earthing terminal.
It seems to me there should definitely be a grommet (though it will be
a tight fit with six wires entering), the live wires should be sleeved
in brown, there must be a better way to terminate the unused cables
You would normally only sleeve a wire when it is being used for a
purpose that conflicts with its colour. So for example, in a single "one
way" light switch you will typically have two wires *both* of which are
live - one permanent, one switched. Since this is commonly supplied with
a normal T&E cable, one should over sleeve the black/blue in Red / Brown
(depending on the colour scheme being used), to indicate the change of
use. Again however is is very common for this to be missing. For an
electrician, they may disregard the convention since it is "obvious"
that is what is going on.
Thanks. I get that for the red ones. We discussed this with my
previous switch. My bigger concern is the black one, which is
ambiguous. I cannot responsibly sleeve it as earth if I don't know.
Arguably if you are poking about in the back
of switches, then it should ideally also be obvious to you as well.
Agreed, but to be fair I did identify the live cables.
(The sleeving is still very handy, when there are multiple cables - say
in a ceiling rose, since it makes identifying the switch cable easy when
the rose has been disconnected. As evidenced by the number of posts we
have had here over the years along the lines of "I changed the ceiling
rose, and put all the reds together and all the backs together, and now
the circuit trips when I turn the light on")
and especially it is concerning that the neutral could be connected to
the earth terminal (which then connects to the screws for the the
switch).
Do you know if it *is* actually neutral though?
Well, no. This is my question, how to find out without taking the
house apart!
What colour should be used to sleeve a disused wire?
Depends on if it is still connected to anything. The "by the book" way
of dealing with unused wires is they should be made off in an unused
terminal, and connected to earth at at least one end. In the latter case
you could sleeve it in green/yellow.
In reality, taped over wires are common. Folded in some sleeving is also
common ( and arguably better than tape where the glue could fail over
time and it comes unwrapped).
Well, yes. The adhesive seems to be deteriorating here.
Can I fix it,
Is it broken? Is there an immediate safety risk to users?
If not it might be better left alone.
It's more of a theoretical risk if the black wire is neutral, in a
fault situation could the two screws not become live? Also, for a
future inspection I would like to regularise the position.
or is it time to call in the experts? My friend (who is
a retired electrical engineer) knows more about 11kV though I expect
the general principles are the same :-)
Surprisingly there can be quite a big disparity between distribution
side, and consumer side as to what is normal and accepted.
I am reluctant to ask my friend but I'm sure he would fix it for a
curry.
What do the bright sparks think?
Time for tea :-)
:-)
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