UK Took down light to fix pendant light. Wires are live but nothing works, not even the old light now

[LMbessy]

Tested all wires from ceiling and the switch. Both have power.
But nothing works!!!
Should’ve been a simple switch over but now not even the old light fitting works. What the hell has happened?!!!

 

[westward10]

Some pictures might help.

 

[LMbessy]

Light switch - everything is wired up exactly how we found it before taking off - not a thing changed

 

[Moley]

What did you test for power with? If it's one of those pens that lights up then it could be giving a false live reading by picking up induced current from elsewhere. Do any other lights on the same breaker work?

 

[Avo Mk8]

There's not a grub screw in the light switch (or light fitting) accidentally tightened onto the wire insulation rather than the copper, by any chance?

 

[littlespark]

You may be able to pick up lives with a pen, or non contact detector, but they don’t work on the neutral side.

A photo of the fitting will help… if it’s one of those badly designed decorative things, the connectors will be too small, the casing has no space, and there’s nowhere for the earth wire to go…

 

[brianmoooore]

You may be able to pick up lives with a pen, or non contact detector, but they don’t work on the neutral side.

They do when a lost neutral is the problem. If more wires than should be are 'live', then that's likely to be the clue to follow.

 

[LMbessy]

What did you test for power with? If it's one of those pens that lights up then it could be giving a false live reading by picking up induced current from elsewhere. Do any other lights on the same breaker work?

All do

 

[LMbessy]

They do when a lost neutral is the problem. If more wires than should be are 'live', then that's likely to be the clue to follow.

Only live on the return - we put everything back as it was before & no light at all.

 

[LMbessy]

You may be able to pick up lives with a pen, or non contact detector, but they don’t work on the neutral side.

A photo of the fitting will help… if it’s one of those badly designed decorative things, the connectors will be too small, the casing has no space, and there’s nowhere for the earth wire to go…

 

[LMbessy]

 

[Avo Mk8]

Is it possible the old and new lights don't work for two different reasons?
I guess you've tried to eliminate the possibility of faulty bulb, and faulty new fitting, eg by putting a plug on the new light to check it works?
With screw-in bulbs, depending on design of bulb and holder, I've occasionally had the outer bulb contact (at the bottom of the holder) failing to connect with the bulb thread, even with the bulb screwed in tightly. The remedy can be to bend the contact inwards a bit - with the power off obviously! ️

 

[westward10]

We need to see the connections at the lighting point.

 

[LMbessy]

Is it possible the old and new lights don't work for two different reasons?
I guess you've tried to eliminate the possibility of faulty bulb, and faulty new fitting, eg by putting a plug on the new light to check it works?
With screw-in bulbs, depending on design of bulb and holder, I've occasionally had the outer bulb contact (at the bottom of the holder) failing to connect with the bulb thread, even with the bulb screwed in tightly. The remedy can be to bend the contact inwards a bit - with the power off obviously! ️

Done all of that, tested both light fittings with a plug

 

[LMbessy]

We need to see the connections at the lighting point.

Posted a picture of the connections at lighting point already

 

[brianmoooore]

I take it that your last pic. is the supply to the old light?
In that case, you don't have the usual problem when we get these threads of nine or more wires to sort at the lamp, but it does tell us (from the green sleeving), that the wiring is fairly old, and that the connections between the switch, supply and lamp cables are elsewhere, probably in a junction box.
It's very possible that in disturbing the cable you've pulled a wire from an already loose terminal in that junction box.

 

[LMbessy]

I take it that your last pic. is the supply to the old light?
In that case, you don't have the usual problem when we get these threads of nine or more wires to sort at the lamp, but it does tell us (from the green sleeving), that the wiring is fairly old, and that the connections between the switch, supply and lamp cables are elsewhere, probably in a junction box.
It's very possible that in disturbing the cable you've pulled a wire from an already loose terminal in that junction box.

I thought this too, now how the hell do I find it??? From the room above, under the floorboards?

 

[brianmoooore]

The first thing is that this wiring is 50 - 60 years old, so if typical of the rest of the wiring in this house, it might be time to start thinking about a rewire.
Yes, the normal way to access a joint box would be by lifting the floorboards above, so this is likely to involve some furniture shifting and carpet lifting, and hope that the boards haven't been covered in plywood, replaced by chipboard, etc.
Since moving the wire at the lamp end moved it at the j/box as well, it's likely that the offending item is in the same 400mm wide void under the boards as the lamp, so, once the boards are exposed, work out where exactly over the lamp is and inspect the area across the room at right angles to the direction of the boards. With luck, you'll see a (hopefully) short length of board that has obviously been lifted before, and will find your j/box under it. With even more luck, you'll see a length of board with "j/box below" painted on it.

 

[littlespark]

The joint box is usually on the landing, just at the top of the stairs…. But as above, you’ll need to lift carpets and boards to find it.

It will be a square or rectangle plastic box with all the grey twin and earth cables running into it.


It would be unlikely that the fault was here… but not impossible.
I would spend more time checking the connections at the switch and light fitting before pulling up boards.

Has there been any construction work where the cable might have been damaged?

 

[LMbessy]

The joint box is usually on the landing, just at the top of the stairs…. But as above, you’ll need to lift carpets and boards to find it.

It will be a square or rectangle plastic box with all the grey twin and earth cables running into it.


It would be unlikely that the fault was here… but not impossible.
I would spend more time checking the connections at the switch and light fitting before pulling up boards.

Has there been any construction work where the cable might have been damaged?

No thing has been done construction wise to that area of the house. What we did was take down the original light fitting/ bulb, wired up the new pendant light & then nothing. Checked power is going to all wires light switch end and ceiling light end - there is. Even hard wired the old light fitting up (I know I know) - still nothing. All other downstairs lights work fine.
So after a few hours, put everything back as it was - still nada. So frustrating!!!!!

 

[brianmoooore]

The joint box is usually on the landing, just at the top of the stairs…. But as above, you’ll need to lift carpets and boards to find it.

It will be a square or rectangle plastic box with all the grey twin and earth cables running into it.

I know the sort of box you mean, but I associate these with earlier wiring, often VR. I think I've even seen them used with lead sheathed, and some with cable clamps as well.
I reckon this is more likely to be a round 4 terminal box with a screw on lid and used one per light.

 

[littlespark]

Never seen the round joint boxes being used in this way. Just as addons later on, or maybe a single room where running more than one cable would be a problem.

From my experience, and this could be a location thing, but lighting circuits have either been central joint box, loop in at light, or nowadays, loop in at switch.

This is only for t&e and 3c&e cables.

Older properties may have been done in steel conduit and singles.

 

[brianmoooore]

Must be regional differences - we live and work at opposite ends of the country. The vast majority of rewires I did back in the day were from a mixture of VR, polypropylene and two core PVC to PVC T&E, and nearly all were originally wired with one four terminal j/box to each light.
Never seen conduit in a domestic property to this day.

 

[mainline]

Round junction boxes are very common in the UK for lighting installations