Lighting circuit issue

[psarinuk]

Hello

I've an issue in my new (old) home on the first floor ceiling lights.

When I swich on the light in the smallest (3rd) bedroom, it lights up (not very bright, multimeter showing 120V) but the master bedroom light comes on as well, although quite dim.
When I turn on the master bedroom light, the 3rd bedroom light goes off but the master bedroom light comes on with full brightness.

I checked the switches, they were OK. I've the pics for the ceiling roses.

The master bedroom has a different looking ceiling rose compared to the 3rd bedroom (could it be fed via a junction box - I can't find any in the loft)? I've checked the wires in the loft between the 2 rooms and above their ceilings and they seem OK.

Any ideas how the 3rd bedroom switch is feeding the master bedroom light? Whatever is switched on, the "line" conenction at the RHS of the master celiing rose never gets the power (the screwdriver tester never lights up).
The middle is the "loop" which is fed by live and is therefore always turns ON the tester.

The left is the "neutral" which gets the tester light ON whenever the master bedroom switch or the 3rd bedroom switch is turned ON.

Master bedroom ceiling rose:

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3rd bedroom celing rose:


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Thanks for your help in advance..

 

[ericmark]

Neutral and switch wire swapped in master bedroom.

 

[SUNRAY]

Neutral and switch wire swapped in master bedroom.

Yes


Take care when you start handling the wires as your rubber cables are showing significant signs of deteriation and need attention, this should have been picked up on the inspection which was done as part of the property purchase.

 

[psarinuk]

ericmark, sunray

First of all, thank you very much!

What I understand is:
1. One of the black wires from the LHS on the rose needs to be swapped with the black wire on the RHS next to the brown one.
2. To find out the switch wire, I will remove all 3 black wires and turn the master bedroom switch on. That will give me the active black on the tester. Should that be next to the brown one on the RHS to feed the light?
The other 2 can go on the LHS.

Sunray, I checked the condition of wires in the loft and they looked Ok (insulated sheath all over). Its just the wires that are coming out of rose that seem quite frayed. Do you think this should have been picked in the HIP as the survey I had for the mortgage was quite a basic one.

Thanks so much once again guys. you rock!

 

[ban-all-sheds]

2. To find out the switch wire, I will remove all 3 black wires and turn the master bedroom switch on. That will give me the active black on the tester.

Normally I'd say:

No - don't do that. Turn the power off and identify the switched live by continuity testing on a dead circuit, not voltage testing on a live one.

In this case I'm just going to say:

No - don't do that.

Leave it alone until the wiring is replaced, and put up with things not working 100%. If you can, don't even try to replace the rose in the 3rd bedroom, unless those cables are PVC. That rubber insulation could disintegrate at any time, and leave you with no lights at all, or with a fire risk.

Sunray, I checked the condition of wires in the loft and they looked Ok (insulated sheath all over).

But what's the sheath made of? PVC or rubber?

Its just the wires that are coming out of rose that seem quite frayed.

Some or all of your wiring is decades old rubber insulated stuff which is badly deteriorated. Getting that sorted out is a matter of great urgency. Maybe there are only a few odd bits left that you can replace, maybe it's pervasive, maybe there are lots of odd bits left in places you cannot see.

Do you know how old the previous owners were, and how long they'd been there?

You must get a proper inspection done asap. If you've got cable which could easily have been replaced (e.g. lighting circuit in the loft) and hasn't been, what have you got lurking under floors etc? You can't even just trust looking behind sockets or inside the CU, for example, as sadly it is not unknown for people to join bits of PVC to the old VIR with choc-block and then push it down out of sight.

I'm afraid it might be floorboards up time.

Do you think this should have been picked in the HIP as the survey I had for the mortgage was quite a basic one.

I wouldn't expect that - the "surveys" done for mortgages are very basic indeed.

 

[SUNRAY]

ericmark, sunray

First of all, thank you very much!

What I understand is:
1. One of the black wires from the LHS on the rose needs to be swapped with the black wire on the RHS next to the brown one.

yes

FIRST make sure you turn of the power and check that the rose is dead

2. To find out the switch wire, I will remove all 3 black wires and turn the master bedroom switch on. That will give me the active black on the tester. Should that be next to the brown one on the RHS to feed the light?
The other 2 can go on the LHS.

Yes but to avoid disturbing the wires too much only remove one of the two blacks for your test if you are lucky it will be the masterbed switch, swap that with the one next to the brown.
Only disturb and check the other of the 2 blacks if your were unlucky with your first choice.

Sunray, I checked the condition of wires in the loft and they looked Ok (insulated sheath all over). Its just the wires that are coming out of rose that seem quite frayed. Do you think this should have been picked in the HIP as the survey I had for the mortgage was quite a basic one.

There should be a PIR [periodic inspestion report] whenever the property changes ownership and its often 'that bit' of the HIP. The basic survey should have had some sort of comment about age of the electrical installation. My gut intinct is the rubber cabling is around 50 years old and judging by the picture needs to be replaced, it certainly needs to be looked at properly.

Thanks so much once again guys. you rock!

Your welcome, sorry the last comments were not what you wanted to hear

 

[psarinuk]

As always, it can never be success first time for me

Swapped the 2 blacks between the LHS and RHS of the master bedroom rose. Power ON, fuse blown.
Now swapped the blacks back to their original (I think), but the light stays on. Light switches from master and 3rd room do not make any difference.
3rd room light does not come on and master room light does not go off.

Both live and neutral have power at the moment at the light switch (tester glows at both).

2 neutrals at the rose have power (tester ON), they are connected together at LHS of the rose.
1 nuetral does not have power and its currently connected to the RHS of the rose (where it says LINE).

In the 3rd room as well, there is power at both live and neutral at the rose.

Your analysis please?

 

[sparkwright]

Can't see what you have in the second picture.

It looks like two cables ie four wires.

I would assume one black at neutral
one black at switched live
both reds in the middle loop terminal.

I take it there is a two core cable at each switch.

You need to identify the switch cable ie the cable that goes to the switch.
This cable will go the rose, and the red should go to the middle loop terminal,
and the black should go to the switch live terminal, with the brown flex wire.
The remaining two blacks go the neutral terminal, with the blue flex wire.

Check this on all the lights.

And for god's sake, get your lighting re-wired and the rest of the house checked over. That wiring was old hat 50 years ago.

 

[electronicsuk]

And for god's sake, get your lighting re-wired and the rest of the house checked over. That wiring was old hat 50 years ago.

...and don't do any decorating until you do, or you might live to regret it when you have to rip your walls to pieces during the rewire that it looks as if you'll be needing.

 

[SUNRAY]

Ok

As a matter of urgency get the wiring check by a professional, it is 50 years old and is perished, we can all see that from your pictures.

Please read through this several time and understand it before you start.

I don't like to describe this but I know you are going to persevere with it.

You obviously don't have a multimeter so I assume you only have the neon screwdriver and you appear to be comfortable testing with it with the power on.

PLEASE MAKE SURE THE POWER IS ALWAYS OFF WHEN YOU MOVE OR TOUCH ANY WIRES

PLEASE INSPECT THE WIRES AT EVERY STAGE TO ENSURE THE INSULATION IS NOT BREAKING UP BEFORE YOU TURN THE POWER ON

DO NOT MOVE THE WIRES MORE THAN IS ABSOLUTELY NEEDED

Up to point 14 there should not be any sign of either of the lights coming on.

If any any point there is any sign of the insulation breaking up then STOP and call in professional help

If at any point there is any deviation from this list then STOP and call in professional help

1. Switch off power remove all 3 blacks and position them so they stick out in such a way you can test them for live and they cant touch anything else. INSPECT THE INSULATION

2. Turn both lights on.

3. Turn power on.

4. Be VERY CAREFUL and make sure you don't touch the wires, test all 3 blacks for live.

Two should be live and one should not be live, carefully note which one is not live. This will be the neutral.

5. Turn Power off and check nothing is live, Terminate the neutral wire [the one which was not live] in the brass strip marked neutral and has the blue wire to the lampholder.

6. Make sure the other 2 blacks still stick out and they cant touch anything. INSPECT THE INSULATION

7. Switch off the bed 3 light switch.

8. Turn on power.

9. BE VERY CAREFUL and make sure you don't touch any wires. Test the 2 blacks for live.

One should be live, this will be master bed switch. The other will not be live, this will be the neutral feed to bed 3.

10. TURN OFF POWER and check everything is not live.

11. Terminate the black, neutral feed to bed 3 [ the black which was not live] in the brass strip which has a blue wire and a black wire.

You should now have three reds in the middle brass connector, and two black and a blue in the left brass connector, a brown in the right [line] connector and one lose black.

12. Make sure the lose black is sticking out and it cant touch anything. INSPECT THE INSULATION

13. Switch off master bed light switch.

14. Turn power on.

Up to this point neither of the lights should have been lit.

15. Switch on bed 3 light switch, bed 3 light should come on.

16. VERY CAREFULLY test the 3rd black wire, it should not be live.

17. TURN OFF POWER and check that nothing is live Terminate the lose black wire in the right hand brass connector [marked line] whicH has the brown wire. INSPECT THE INSULATION

18. Turn on power and check switch on master bed light, it should come on.

19. Recheck operation of both lights to ensure there is no error.


I suggest you leave the cover off and the fitting hanging in bed 3 to avoid damaging the perished rubber and get it checked by a sparks.

I cannot be held responsible if any thing goes wrong.

 

[ban-all-sheds]

I cannot be held responsible if any thing goes wrong.

Au contraire.

You've told him to use a neon screwdriver, a device you know to be at best unreliable and misleading and at worst dangerous.

You've told him to fiddle with wiring when you know that the insulation is disintegrating almost as you watch it.


psarinuk - Sunray might be correct in that you are determined to persevere, but if you do you're a fool, and that's all there is to it.

 

[psarinuk]

Gents, many thanks for your replies, especially sunray for his "lighting circuit wiring for dummies" guide much appreciated.

A few points from my side first of all:
1. Just bought a house a few months ago and have a 4 day old baby as well in the house, so there is no scope of decoration while I plan & repay some finances.
2. Wiring would be top of my list when it comes to decoration as its an old house (lady who sold to me was quite old and lived there for over 20 years). New wiring would be done within this calendar year.
3. Checked the wiring everywhere in the house. The socket wiring seems new everywhere with new colours. The insulation sheath of lighting circuit wires is PVC and looks normal everywhere (in loft). Took the sheath off by the roses and it looks brand new wires inside, but as you say they are rubber coated red/ black wires, so you never know. Will get all the lighting circuit atleast to new wires this year. Any idea of costs involved? Its a small 3 bed terraced house.
4. Once this light is sorted, I am going to take all the roses off and put "coloured" insulation tapes for each wire that I take off (one by one). WITH POWER OFF.
5. I am a disgnotics engineer (cars) by profession and confident but careful while dealing with live power wires, and I have a multimeter too. The only reason I could not check with multimeter is because I did not take the red wires off the rose to check continuity for the switch wires (with switch ON and main power OFF). But with Sunray's guide, I don't think I will need to use it.

SUNRAY
Step 9: As 2 blacks were live before (step 4) and the one that wasn't would be connected to neutral block, are you sure that the other will not be live (can't remember the state of 3rd bedroom switch at this step from last night as wife was controlling it)?
Step 16: I am again wary of this step in my house as you say this one should not be live (it was live at step 4).
But your steps are so well defined that they are worth a try. I will stop at any step where outcome is different to what you wrote.

If any of you guys come to Basildon, it would be a pleasure to buy you a pint.
Thanks and Best Regards once again

 

[ban-all-sheds]

The socket wiring seems new everywhere with new colours.

You can't even just trust looking behind sockets or inside the CU, for example, as sadly it is not unknown for people to join bits of PVC to the old VIR with choc-block and then push it down out of sight.

 

[psarinuk]

Hi BAS

I've some floor boards off and as far as I can see, it does not seem to be the case. But thanks for highlighting anyway.
If costs allow, I may get the whole house rewired.

 

[psarinuk]

Just been to home to fix this on my lunch break as I was a bit anxious.

As previously thought, when I reached step 9:

9. BE VERY CAREFUL and make sure you don't touch any wires. Test the 2 blacks for live.

One should be live, this will be master bed switch. The other will not be live, this will be the neutral feed to bed 3.

3rd bedroom switch is turned OFF, still the 2 blacks are showing live.
Also there is live at both blacks (I checked brown and blue as it was easier) in the 3rd bedroom even when the switch is turned OFF.

Could there be any mis-wiring in any other ceiling rose upstairs? Rest of all lights seem to be working fine but I still have the urge to open their ceiling roses to spot anything obvious.

I am attaching a couple of pics of 3rd bedroom ceiling rose as the previous pic was not very clear. Not sure if this one will make any difference but there are 2 reds (together) and 2 blacks going on top of this ceiling rose.

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