UNSWITCHED FUSED SPUR

Discussion in 'Electricians' Talk' started by CRAIG DODD, Jan 9, 2022.

  1. CRAIG DODD

    CRAIG DODD New Member

    Hi,
    25 years I have owned my house and at the top of the stairs there has always been an unswitched fused spur.
    Never really thought much about it!!!
    Until today!
    We are have major work done on the house...plastering walls, new stair banisters and a new bathroom.
    We have always had to run an extension lead up the stairs to hoover etc.
    So I had a thought!! Could I turn the unswitched fuse spur into a 3 pin plug socket.
    I took the mounting screws out and had a look at the back of the faceplate just to see what has been hidden for 25 years.......
    There were 3 individual cables coming up from the wall. Two lives went into the left hand 'IN' side connection and one live went into the left hand 'OUT' connection.
    The two 'LIVE' cable neutrals (BLACK) both went into the right hand 'IN' side and the single 'LIVE' cable neutral (BLACK) went to the right hand 'OUT'
    Whatever I did with with the fuse.....located or removed! This made no difference. Both the left hand 'IN' & 'OUT' were live.
    Not sure if any of this made any sense...when I removed the fuse.....nothing seemed to go off!!!!
    Not got any clue where this goes or what it does!!!
    Its only been like this for 25 years!

    Can this become an upstairs socket? :)
     

    Attached Files:

  2. terrymac

    terrymac Screwfix Select

    The outgoing cable is going somewhere. Outside light ,burglar alarm, light fitting under the stairs ,or a cupboard. Have a closer inspection . Of course it could be just terminated somewhere ,and not supplying anything ,which poses the question ,why was it installed in the first place .
    What are you using to test for voltages present ? It's unlikely that removing the fuse from the fcu would still leave the load ( out) terminal live as well as the supply side ( in).
     
  3. elecstick

    elecstick Screwfix Select

    When you remove the fuse the RHS should be dead, check again. If its still live, remove all ccu fuses/ switch off mcbs one at a time to ascertain which one kills the power.
     
  4. CRAIG DODD

    CRAIG DODD New Member

    I will confess....I am using a magic glowstick screwdriver.
    I will use a multimeter tomorrow and do it properly!!! :)

    Please watch this space! :)
     
  5. NoelK388

    NoelK388 New Member

    You're quite right.
     
  6. CRAIG DODD

    CRAIG DODD New Member

    Hi again,
    Quick update…. Used my multimeter!

    230V at IN & OUT with or without the bloody fuse in!!

    What next please?
     
  7. terrymac

    terrymac Screwfix Select

    Where are you taking the voltage readings ? Red probe on what ,black probe on what ?
     
  8. CRAIG DODD

    CRAIG DODD New Member

    Red probe on red out
    Black probe black out

    please tell me where I should probe?
     
  9. terrymac

    terrymac Screwfix Select

    That's fine.
    And red in and black in ,one probe to each ,also reads 230V ??
    Show us a picture of multimeter on the setting you are using.
     
  10. SGM18

    SGM18 Member

    I bet your neighbour is wondering why the bloody washing machine keeps cutting out
     
  11. CRAIG DODD

    CRAIG DODD New Member

    Yep that’s exactly correct…. Multimeter set to AC V 750
     
  12. terrymac

    terrymac Screwfix Select

    What amperage is the breaker ,or fuse that protects the circuit that this FCU is on. Do you know if the circuit is a ring final ?
    I suspect it is ,and the FCU is incorrectly wired ,with each leg of the ring connected either side of the FCU ,but more testing would be required.
     
  13. CRAIG DODD

    CRAIG DODD New Member

    Quick update....
    The 'FUSE' is on the main ring main as far as I can tell..
    Pulled the mains 30A fuse in the consumer unit and '0' volts on the multimeter.
    Replaced the 30A all back as was.
    Removed the 'OUT' single red and black cables from the FCU and multimetered the 'loose' cables.........230V

    What next please!
     
  14. terrymac

    terrymac Screwfix Select

    Seperate all 3 cables from the fcu. Put into insulated terminal blocks ,so all 9 conductors are in individual terminals,and none are in contact with each other.
    Take one cable at a time and take voltage readings between its line and neutral conductors, and it's line and earth conductors.
    I would expect two of the cables to give readings of 230V. And one cable not .
     
  15. CRAIG DODD

    CRAIG DODD New Member

    O.k.
    Just separated the cables...forgot to separate the earths...is this a huge issue, if it is I will do it again!!
    All three lives and neutrals were separated and ALL THREE WERE 230V
    Did connect multimeter to live and earth 'bunch'......also 230V
     
    Silver57 likes this.
  16. terrymac

    terrymac Screwfix Select

    Each grey sheathed cables line to neutral reads 230 V ?
    And when the 30 amp fuse is removed from the circuit are all three cables dead ( 0 voltage) ?
    Can you show us a pic of fuseboard and meters etc ?
     
  17. elecstick

    elecstick Screwfix Select

    And if one at a time doesn't work, do two at a time
     
  18. CRAIG DODD

    CRAIG DODD New Member

    Yep, all three dead when 30A fuse removed!
     
  19. terrymac

    terrymac Screwfix Select

    Obviously a hybrid circuit ,possibly figure of 8 . How competent are you working with electricity ,could you safely work in the fuseboard ?
    And how about pics as I requested ??
     
  20. CRAIG DODD

    CRAIG DODD New Member

    One quick pic of what I am working with.
    In the 'top' of the mains power circuit there are three red wires.....all the neutrals in the house go to a common neutral as do the earths.

    upload_2022-1-14_8-31-4.png
     

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