Lights stopped working overnight

Discussion in 'Electricians' Talk' started by Ormondroyd8ftTall, Sep 19, 2021.

  1. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    Hi all,

    Recently passed my AM2, so im fresh out there with a lot to learn.

    Recently moved into a house that needs re-wiring. All lights in house are on one breaker and i am separating that into upstairs and downstairs MCB's. I have found the upstairs lighting junction box in the loft and disconnected everything. I have traced all the cables and and found they have been wired with the permanent live in common at light switches. This is my first time working with a lighting circuit with the permanent live wired to commons first, i usually practice with permanent live in and out at each light fitting, daisy chaining until end of line. I am re-using the light switches, as the missus wants as little chasing as possible as we are living here and money is abit tight. I have rewired the power to the lights from switch with new 1.5 twin.

    This is how i've wired it using the existing switch wires.
    • Permanent live from 6A MCB ( separate to existing lighting MCB), to 5-way wago block in junction box.
    • Common from each existing light switch at room 1, 2, 4 and 4, into wago block at junction box with permanent live.
    • Wired new 1.5 twin to each light fitting back to junction box.
    • Live for each light fitting in with each light switch L1 switch wire in 2-way wago at junction box
    • Neutral for each light fitting, in with new lighting neutral from board at junction box with 5-way wago.
    • All earth from light switches, light fittings and board connected together at junction box.
    All upstairs lighting worked yesterday, not today and i'm struggling to understand why. I have 200v between live and earth at each light fitting when light switch is off, and 240v when switch is on. I have 60v at neutral in each fitting when switch off, and 120v when switch on.

    I have repeatedly checked all connections at each switch, light fitting and junction and is wired how i feel correctly. I don't feel as though i am losing a neutral anywhere and all connections are mechanically sound.

    I read something about phantom voltage but i have no idea what this is.

    Could i have some advice please, whilst waiting, im gonna disconnect whole circuit and connect back up one light at a time until the circuit doesnt work.

    Thanks in advance
  2. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    Update. Right i've gone and wired up first light...

    • Permanent live from board to common at switch.
    • Switch wire in with live at light.
    • Light neutral in with neutral at board.
    • Switch, light and board earth all together.
    Still nothing.....I have 240v across permanent live and earth when is switch is switched in both positions obviously. 0v across earth and switch live when switch is off then 240v when switch is on as normal. But 200v across live and neutral when switch is off, 60v when switch is on.

    All i can think is that im possibly sharing a neutral somewhere are the board?? earth and neutral are in correct terminals at board corresponding with the MCB. I have no break in cable anywhere.

    I'm lost.....
  3. terrymac

    terrymac Screwfix Select

    The work you are doing is notifiable to local authority building control. How do you propose to comply ?
    I have no wish to be offensive ,but I think you are out of your depth.
  4. Tony Goddard

    Tony Goddard Screwfix Select

    The mistake you have made is to attempt to re-invent the wheel re-configuring an existing set up. To separate the upstairs and downstairs you only needed to identify the T&E carrying the perm live and N from downstairs to upstairs, unhook it from downstairs and run in a new supply from the board.

    By disconnecting the lot you are now in a position of having to work out what every cable does and re-connect, thats a lot of pfaffing about. I would advise finding that supply cable, then working out which cables to to switches, and which to pendants/downlights and start again, draw yourself a diagram as you go, as you know the basic supply - switch - lamp - neutral concept is very basic, its just the configuration that becomes confusing.

    As Terry says, this is notifiable because you have created a new circuit, you need to address that issue somehow.

    Do you have access to test gear?, at a minimum you need to be able to test the earth loop.

    I'm not going to chuck stones, you have done what many, many newbies, including myself back in the day have done, you have rushed in, pulled everything out and ended up the stream and no paddle - just be glad its not a customers house, mine was, I pulled out a 14 way DB on singles without labelling them - the gaffer threw a drum of 4mm at me!! and I thought I'd done well!!

    Always investigate exactly what is what before you dismantle anything, if you cant understand how it works, you can't fix it - only start to pull wires out once you have established what they do, and have labelled them. The one thing they can't teach in college is real world naffed up faulty, rat chewed, diy bodged wiring.

    If you need more help, photos are king!
    seneca likes this.
  5. Tony Goddard

    Tony Goddard Screwfix Select

    PS a phantom or induced voltage is a voltage that can be detected on a technically dead conductor as it being induced from a nearby live conductor or another cable, same principle as a transformer. they have no current to speak of, so as soon as you put a load across they vanish if you are using a budget multimeter which draws hardly any current these often show up, professional kit tends to be better at not showing them because it has better shunt arrays (resistors in parallel with the meter).
  6. Bob Rathbone

    Bob Rathbone Screwfix Select

    I think you need an electrician and to question the effectiveness of your training. Sorry to be blunt, I spent most of my working life training electrical apprentices at a local college. I would expect every one who achieved NVQ 2 to be able to successfully locate faults such as this, that's long before they went to AM2.
  7. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    'Sorry to be blunt', I appreciate your concern but I have asked for help and advice. In return you've basically called me incapable and said I should know what the fault is. As such an experienced electrical tutor I would have thought you would have been quick to give your wise advise, just as you were to criticize, belittle and give no help whatsoever. Especially as its such an easy fault, so as pre-AM2 Students would be able to identify. I'm surprised you haven't stated what the fault is straightaway given your experience.

    I'm still learning, and will be doing so for some time.
  8. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    Thank you for the advice, yes this will be a very good lesson!

    I'm sorting the work with our local authority
  9. Tony Goddard

    Tony Goddard Screwfix Select

    The method you have used in college of looping the perm live through each fitting, a live and switch live to the switch was the defacto standard for quite a long time. It is now becoming more common to have the loop in and out at the switch with the neutral looping through too, this gives a neutral at the switch point which is needed for lots of smart switches.

    There is a method using junction boxes up in the ceiling for the loop through, having only one T&E present at both switch and fitting, this was common from the early days of electricity until the 70's when the roses with a loop terminal became more popular.

    Another method uses a wiring centre junction box to handle all the connections, again just leaving a single T&E at every switch and fitting. This was popular in council owned properties, often the wiring centre box is in a cupboard or on a wall of the floor it serves.

    Yet another method uses single & earth cable throughout, looping the live through the switches and neutral through the fittings. The circuit diagram for all of them is the same.

    In you case, the fact it worked, then didn't would suggests a connection may have failed - if the MCB didn't trip out you can pretty much rule out a mistake joining L to N. I would first double check all the connections, gently pull the wire in the wago, not only does this check its in firmly, it causes the spring contact to dig further into the copper.

    In some respects this is a good learning experience for you as you are encountering some real world issues that can't be easily demonstrated in a teaching workshop, but with the benefit of the fact its your place, not someone elses.

    I've been in this trade 20 years now, and if I've learned anything it is don't take anything at face value, establish whats what through a thorough examination and some testing before getting your tools out - some things, such as borrowed neutrals can quite literally be fatal if you don't catch it. If you havn't got one invest in a good two pole tester with a continuity function, you can figure out a lot with one of those.

    I'm guessing you might not have purchased a tes set yet, as they do cost £££, but it is an essential tool, i use a Megger, which is flippin expensive (I've become a brand addict, the power of marketing), my mate has a DiLog, which is a capable and much more reasonably priced unit.
  10. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    'Another method uses a wiring centre junction box to handle all the connections, again just leaving a single T&E at every switch and fitting. This was popular in council owned properties, often the wiring centre box is in a cupboard or on a wall of the floor it serves.'

    This is the method that has been used for the upstairs and downstairs lighting

    Thanks for your advice]
  11. Bob Rathbone

    Bob Rathbone Screwfix Select

    OK, look to the work you did with conduit systems when you wired lighting, unless you used 3 plate in that also. The wiring in your home is done in the same way as a conduit lighting system should be done. I did not place any blame on you but pointed directly at the quality of the training you received. This is not your fault, you have not been given sufficient support and input during your training, that is where it appears that the issue lies. When you say you have taken and passed AM2 it must put you at least 21 years old, you should have been made aware of this type of lighting wiring system by now. You nor any other student, can be blamed for information not given.
    adgjl likes this.
  12. Bob Rathbone

    Bob Rathbone Screwfix Select

    OK lets try to be positive. The lights need re wiring, 1.0mm T&E is not expensive, buy a roll and re wire the upstairs lights with the new supply down to the board. Run a 3 core & Earth from the landing light switch into the hall light switch to control the landing light 2 way. Use the existing switches and roses to save money, you can change them later. That will work using circuits you are familiar with. Now re wire downstairs lights re using accessories. Your problem should now be solved and half the re wire done. Don't concern yourself with the need to notify, it's your house, I will be shot down for that! As finances improve you can change accessories and re wire the rest of the house, changing the board last of all. You are an electrician, act like one, use your knowledge and don't panic, a bit at a time and double check every connection by pulling it. Good luck.
  13. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    Thanks for the advice, i do appreciate it.

    I ended up re-wiring the switches also, so the whole circuit (lights, switches, main feed) completely new with no existing wires being used. It still didn't work. I have moved the main feed, along with the earth and neutral of course to the other side of the split load board, which the other RCD is serving and it's now working. I currently have two still on the split load side where i had the lighting i have had no problems with any of those circuits.
  14. Bob Rathbone

    Bob Rathbone Screwfix Select

    On the split load board, do you have any issues with other circuits on the dodgy side, could be a faulty breaker or the bus bar connection not in right.
  15. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    No the shower circuit and immersion circuit are currently working fine. I had power all the time so unsure about faulty breaker. Possibly fault with neutral bus bar?
  16. Bob Rathbone

    Bob Rathbone Screwfix Select

    No, I rekon the breaker has been fitted to the busbar on the wrong side of the clamp, it's easy to do if the clamp on the breaker is not fully opened during fitting. Try removing the breaker from the bus bar and re fitting.
  17. Ormondroyd8ftTall

    Ormondroyd8ftTall New Member

    ok thanks, i will try that. Although we have been out for the day and just came back, as i said lights were working this morning. They have now gone again, with nothing tripped!!
  18. Bob Rathbone

    Bob Rathbone Screwfix Select

    Try disconnecting the lights from the CCU and fit a 13A plug on the supply to the lights, with a 5A fuse, plug it into an extension lead from a socket, then see if the fault goes away, if it does then the issue is with the CCU, if it persists the issue is with the circuit.

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