Upstairs downstairs tripping the board

Discussion in 'Electricians' Talk' started by Robert Lampard-Jones, Jul 28, 2021.

  1. Hi, I'm hoping that this forum with the font of knowledge that you all have can help with a bit of a weird one....

    Now before anyone burns me down in flames I understand that I would like to think I'm a competent Diy'r and no expert, but I also realise that when I im of my depth I will get help, partly why I'm on here.

    I have swapped out all our light switches, for touch ones. All was going well....... lol famous last words. Got them all fitted then trip trip trip the mcbs go, I narrowed it down to the 2 way switches on the stairs. This is when I called a sparky in to sort it out. Basically I had forgotten to label up the ring cables and separate the switched feeds to the lights so I had put for example a switched feed into the common live of the ring circuit. Any way sparky fixed the mixed up ring for the lighting circuit and switched feeds with his multimeter which helps.
    Now the issue we have is that all the lights switches work no problem, provided that we switch on mcbs downstairs lighting first then upstairs, if the downstairs mcb is off and we turn the upstairs lighting circuit on first the main fuse mcb trips the whole house.
    This can happen if every switch is off and am switching just the lighting circuits on or off so there must be an issue in the upstairs circuit somewhere I have checked I haven't screwed into a cable in a backbox as all the cables terminate in the back box and not a ceiling rose. I have now invested in a multimeter but as said previously in the post I have no issue asking for help by calling an electrician but if its a simple thing that I can try to sort it I will but if not I would like some idea of what to ask the original electrician we had before we call him out.

    Sorry for the long post but it's easy to show the problem but longwinded to explain.
  2. Teki

    Teki Screwfix Select

    It is unlikely that your lighting circuits are wired as rings, generally only socket circuits are.

    You probably won't have a main MCB and what you are referring to is an RCD tripping the whole house - please confirm? Post some photos of your consumer unit if you are unsure.

    Have you kept the original switches and would you be able to put them back with identical wiring as you have at present?
  3. Hi Teki,
    Thanks for the reply. Yes I have the original switches but didn't really want to put them all back if I can help it , will do if needed but when all the trip switches are on provided I switch them on in the upstairs first then downstairs they stay on. This is what's puzzling me. It's only if I turn the down stairs off then it trips the whole house. But if I turn off the upstairs trip first it all stays on. Weird. I only said ring because in every light switch back box it has the two lives to continue the feed to the next light switch. Obviously the last one in the line only has the one permanent live into the switch. Any how have uploaded a pic of our CU

    Attached Files:

  4. sparky steve

    sparky steve Screwfix Select

    You have stated,

    “if the downstairs mcb is off and we turn the upstairs lighting circuit on first the main fuse mcb trips the whole house”.

    Can you confirm if it is indeed the main switch, or the RCD tripping. Which RCD is tripping, or both tripping?
    As you state, “The main fuse mcb trips the whole house”.:confused:
  5. Comlec

    Comlec Screwfix Select

    Sounds like you have either
    Incorrectly connected the switch drops so when you switch the lamp on the MCB trips
    Interconnected the two lighting circuits causing the RCCB to operate
  6. Hi Steve,
    Ok I apologise for the lack of terminology and detail, it was confusing the sweet Jesus out of me The switch that trips is both the upstairs RCCD and downstairs RCCD the big red one stays on. But this is only if we switch the UP lighting circuit on first. Switch the down on first both the rccds stay un tripped
  7. If the second is what has happened, the reason for me thinking this is the downstairs by the front door light switch (2 way switch) I could have sworn that it was connected to the upstairs circuit but now is operational on the downstairs circuit. Inside this switch there are 4 cables 3 of them are T+E and the other is the I guess 2 way switch wire grey black and earth. But on the upstairs switch there's 5 cables in there
  8. Hell68

    Hell68 Active Member

    Might be a stupid question.....sorry if it is. But Is the upstairs switch definitely wired up correctly? Only asking as mine did this then worked out I'd copied the wiring like for like but shouldn't have as old switches were L1, L2 and L3. New ones L1 L2 and com

    Attached Files:

  9. Bob Rathbone

    Bob Rathbone Screwfix Select

    You have messed up in the 2 gang switch that controls the hall and the landing light, the one at the bottom of the stairs. The up lights and down lights are on different RCD's and they must not be mixed. If in the hall light switch, you have used the switch feed for the down lights to supply the landing light, then the RCD will trip. I think you need an electrician.
    As a good general rule when changing things on a system that you don't fully understand, you should first take photographs, then change only one item, testing that the system still operates correctly before repeating the process on the next item to be changed.
  10. Not a stupid question at all, I was brought up if you don't know, ask. I believe there set up correctly as the electrician I got to come out as I was getting ratty with it used his multimeter to find the switched live wires to the lights then grouped the remaining lives to the common.
    Hell68 likes this.
  12. I think I agree that it is the stairs that caused this, as all the rest of the switches I had changed were one way, except for the kitchen but these are now all one way. I will call the electrician back out as it was him that wired the stair switches up.
    So this would mean then that there is a permanent live going from the upstairs switch to the hall one as on the hall switches 3 gangs only 1 gang was for 2 way (the upstairs light. And as in the back of the switch I have 2 lives going into the common one of them needs to be capped off so to speak then separating the upstairs from down. Previously on the old type switch there were the small link wires going from common to common on each switch but I don't remember if one linked to the 3rd 2 way gang
    Last edited: Jul 29, 2021
  13. Bob Rathbone

    Bob Rathbone Screwfix Select

    I see, you have 2 switches for down lights, probably hall light and porch, these will probably be linked to get the feed across, and one switch for the landing light, you should not have any links from this switch to the other 2 on the switch plate.
  14. spirits are real 2016

    spirits are real 2016 Screwfix Select

    Where abouts in the country are you..
  15. And I guess because of the old switch had separate commons that needed linking the new one has a shared one just separate and try each one
  16. Down south in sunny nope scratch that windy southampton
  17. MGW

    MGW Screwfix Select

    Clearly only a guess, but my house has a 4 gang switch down stairs with three lights on one circuit and one light on another, so two independent circuits in one switch.

    So it would be impossible to use a smart switch with a common line in and 4 line outs.

    It was wired wrong when I moved in, but worked, until all RCBO consumed unit fitted.

    I am sure if you return to individual coms type switch it will all work.
  18. You my kind Sir have hit the nail on the head, what I didn't realise was that the top of the stairs switch in the down stairs by the door was on the upstairs circuit, I just thought the down stairs was part of the upstairs (if that makes sence). The link wire that was supposed to be current free and a separate communication link between both switches the down tells the top what to do and vice versa, whas the link between the 2 circuits removed this and bingo. I can now have up circuit on with no trips or the down on no trips lol just means I lose the 2 way aspect as I don't really want to have the old switches back on just those 2 switches. Never mind.

    Thanks everyone for there input and a big slap on the face for me for not realising that the up and down circuits were in the same switch
  19. The Happy Builder

    The Happy Builder Screwfix Select

    So you are now unable to turn the lights on at the bottom of the stairs and off at the top or vice versa?
  20. MGW

    MGW Screwfix Select

    I used energenie light switches in my bedroom so I have a remote control and two way switching, wife has the same plus some Zigbee lights again with a remote control, hers Zigbee from Lidi has a magnetic back plate on the remote, so it can be wall mounted just like a light switch.

    I do like the Zigbee remote, but it was only sold as part of a three GU10 spot light unit, I would love some more remotes.

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