Please help me understand my light circuit

[Lipple]

Hello,

I am replacing my pendant light fixture with a low profile (metal) fixture.

I read a good bit and saw how light circuits are wired using the 3 loop method, wired inside the ceiling rose. There is no space in the new fixture, so I figured I would get some wago connectors, a junction box to hold them in the ceiling and some new cable with an earth line, repeat exactly the wiring in the rose and I'd be all done (to be honest, I think I can still do this as long as everything is wired up as it is in the rose, but I want to be sure)

When I opened the fixture I did not see what I expected to. See picture. There is nothing in the loop. I thought perhaps it's the last light on the circuit, but the other lights are wired the same way.



In the switch I got very confused, there is two wires (not colour coded) going into one end, and a live (or switch live?) in the other. See Picture. It sort of looks how they might wire a 2 way switch. But there is only one switch controlling this light.



I cannot make sense of what I'm looking at. There is a smoke alarm in same room which is almost certainly on the same circuit if that makes any difference.

Could you help me understand how this is wired? And maybe confirm if I repeat exactly the way the rose is wired using wagos, that all will be right?

Thank you.

 

[Murdoch]

How old is the property? The wiring?

Looks like you have singles with earth cables.

So easy to use lever wagos and don’t worry about containing them in their own enclosure - as long as the base of the new fitting covers the wagos you are good to go

 

[Lipple]

Property & wiring are brand new - 2023.

But okay, that's good, thank you.

I don't think there is enough space in the new fitting for the 3 wagos I will need. If nothing else I'd have to drill a hole in the fitting base just to fit the extra wires. So I think I'll have to put the wagos in the ceiling.

 

[Andy™]

wired in singles by the looks of it. all neutrals looped through the lights, perm live looped through switch & a SL from switch to light. neutral & SL having a cpc and the perm live no cpc

not a common way to do it but still an acceptable method, although current standards recommend a neutral at the switch

 

[kerching]

Is that brown cable with a white sheath or brown cable and lots of white spray paint ( going off the interior of the back box)?

 

[Lipple]

Ahh okay, that explains it Andy.

It's brown cable inside white sheath I think, single core. The white hasn't been trimmed back.

Thanks all, I'll go with my original plan so should be fine.

 

[kerching]

It's brown cable inside white sheath I think, single core.

Strange. In my mind I thought you couldn’t just run a live on its own and it had to have an earth with it. Everyday is a school day

 

[Andy™]

Strange. In my mind I thought you couldn’t just run a live on its own and it had to have an earth with it. Everyday is a school day

no different to meter tails. same cable type, just smaller CSA

 

[nicebutdim]

PVC/PVC singles are used extensively in domestic lighting circuits on this side of the Irish Sea, but brown is always with an earth. The regulations may not require this (can't be certain without checking), but it's a sensible precaution when cables are buried in walls.

 

[kerching]

no different to meter tails. same cable type, just smaller CSA

I’ve not seen them for years…showing my age/memory oh look,

 

[Andy™]

PVC/PVC singles are used extensively in domestic lighting circuits on this side of the Irish Sea, but brown is always with an earth. The regulations may not require this (can't be certain without checking), but it's a sensible precaution when cables are buried in walls.

cpc isn't an armour. if you damage the cable, chances are you are going to hit only 1 conductor and not live / cpc at the same time

 

[nicebutdim]

cpc isn't an armour. if you damage the cable, chances are you are going to hit only 1 conductor and not live / cpc at the same time

Indeed, but worth mentioning that an uninsulated CPC running alongside a live conductor stands a better chance of doing its job than no CPC.

 

[SPECIAL LOCATION]

I read a good bit and saw how light circuits are wired using the 3 loop method, wired inside the ceiling rose.

When I opened the fixture I did not see what I expected to. See picture. There is nothing in the loop. I thought perhaps it's the last light on the circuit, but the other lights are wired the same way.

In the switch I got very confused, there is two wires (not colour coded) going into one end, and a live (or switch live?) in the other. See Picture. It sort of looks how they might wire a 2 way switch. But there is only one switch controlling this light.

I cannot make sense of what I'm looking at. There is a smoke alarm in same room which is almost certainly on the same circuit if that makes any difference.

Could you help me understand how this is wired? And maybe confirm if I repeat exactly the way the rose is wired using wagos, that all will be right?

Ahh okay, that explains it Andy.

It's brown cable inside white sheath I think, single core. The white hasn't been trimmed back.

Thanks all, I'll go with my original plan so should be fine.

Just to add a bit more info that may assist you further.. Or just help others reading this post later...

From my experience the majority of DIY wiring replacement accessory problems happen with lights and switches NOT sockets..
As sockets simply need a live, neutral and earth put into the correct terminals and all is good..

But lights have the extra "SWITCHED-LIVE" problem that many DIY'ers forget about..

e.g. For the purpose of this description lets forget about the earth, (CPC), connections, as they should be taken to every accessory point anyway!
But in a very basic single switch and single light circuit all you need is

(a) A permanent live to the switch. (A permanent live is not needed at the light itself)
(b) A neutral to the light fitting. (A neutral is not needed at the light switch)
(c) A switched live between the light switch and the light fitting.

If you wanted to add second light you would need to get a permanent live from the first switch, and a neutral from the first light, then add a switched live between the second switch and the second light..
(which looks like the arrangement you have got?)

However when using multi-core cable rather than singles it is common to take the permanent supply cable from the CU to either the light OR the switch.. whichever is most practical for the installation, then loop from that..
Which may be the assumptions made on some of the reading you did about how lights are wired!?

But hazards that can often trip up a keen DIY'er who's just watched You-Tube electrical work video showing how easy it is!!!

It is not uncommon to find a mix of everything from Loop at light, Loop at switch, Singles to light & switch.....etc..
or any combination thereof!!!

Twin brown, or older twin red, (live) cables are available to do permanent & switched live functions from a switch..
But often a Blue, or older black, (neutral) wire is used as a switched live.. It should be sleeved or marked to indicate it is switched live and NOT a neutral... So NEVER assume a blue, (or black), at a switch is a neutral unless you have proved otherwise!

Two-way, three-way, four-way switching etc.... ALL require more than one switched live connection between the switches, 3-core & Earth cable is often used for this function, but sometimes bodged DIY work, (or builders electrics), use an Earth wire from a multicore + earth cable as a switched live between a pair of two-way switches! This is dangerous and can also totally confuse a DIY switch replacement!

The bottom line with any lighting alterations is have you identified where the Permanent Lives, Switched Lives & Neutrals go to????

Plus as has also been mentioned with the increasing number of smart switch devices that require a live and neutral at the switch current regs do recommend consideration of taking a neutral to every switch point as well (559.5.1.208), which can also confuse a DIY'er thinking, why is this neutral not connected to my switch? it must go somewhere or why has it been wired in the first place?

So to summarise..
Lights can be wired in numerous methods.. never assume anything until you have tested and proved the actual physical wiring first..
and ALWAYS keep in the back of your mind the basics of how a circuit works... Supply -> Switch -> Load -> Back to supply!