Help with shower wiring

Discussion in 'Electricians' Talk' started by filrock, Jan 18, 2017.

  1. filrock

    filrock New Member

    Good evening all.
    Quick question if anyone can help.?
    We rent our home and have an 8.5kw shower in and would like to replace with 10.5kw.
    Understand the spur needs to be 10mm wiring with a 40amp fuse at the consumer unit apparently.
    Can anyone ID this wiring that I've attached please? I was unsure if it's 10mm overall....or if I should be expecting a solid 10mm core of copper inner..?
    Many thanks
    Phil
     

    Attached Files:

  2. Rulland

    Rulland Screwfix Select

    Is the earth just one solid core or stranded, if solid it's 6mm, if stranded it's 10mm.
     
    CGN likes this.
  3. seneca

    seneca Screwfix Select

    Yes as Rulland said, look at the earth conductor to confirm.
     
  4. nigel willson

    nigel willson Screwfix Select

    10mm is the cross sectional area of the phase and nuetral, not the physical size of the cable
     
  5. retiredsparks

    retiredsparks Super Member


    ....and then call in a sparks to do the job properly...:cool:
    and get him to check the plumbing as well regarding full bore isolator...:)
    RS
     
  6. Bazza

    Bazza Screwfix Select

    SHouldn't this be a job for your landlord?
     
  7. filrock

    filrock New Member

    Thanks all.
    The earth is split into strands so I'm taking it as 10mm.
    Many thanks
    Phil
     
  8. Dr Bodgit

    Dr Bodgit Super Member

    Just thought I'd mention it but not applicable in this case since the cable is obviously fairly new (being blue in colour), but "old" 6mm cable also has stranded earth (as it is in my house).
     
  9. Pollowick

    Pollowick Screwfix Select


    What are the exact dimension of the outer grey/white insulation?
     
  10. seneca

    seneca Screwfix Select

    That would probably be the old 7/044 Dr. B.
     
  11. Dr Bodgit

    Dr Bodgit Super Member

    Most likely seneca, from 1958.
     
  12. seneca

    seneca Screwfix Select

    Did it start out as a cooker circuit but has been altered to supply a shower? Lot's of the old cooker circuits from that period (and later) were wired in that cable. Nice cable as was the old 7/029 used for ring finals etc.
     
  13. Dr Bodgit

    Dr Bodgit Super Member

    Just a cooker circuit, still in use.
     
    seneca likes this.
  14. Liam Sparky

    Liam Sparky New Member

    10.5KW = 45A not 40
     
  15. Bazza

    Bazza Screwfix Select

    If you were to look at the rating plate, very often if gives rated current at two voltages, possibly 230 V and 240 V and if you multiply each by its respective current, generally only the higher voltage achieves rated kW.
     
  16. Pollowick

    Pollowick Screwfix Select

    Still exceeds 40A though. And at the OP

    Taking it to be 10.5 kW at 240v the current will be 44 A. Assuming the heating element is purely resistive and remains constant then it will be 5.4857 Ohms.

    At 230 V that will give 9.65 kW and 42 A consumption which still exceeds the 40A.

    However, knowing that the UK still provides a lot of the network at 240V the higher figure needs to be considered.
     
  17. Bazza

    Bazza Screwfix Select

     
  18. Pollowick

    Pollowick Screwfix Select


    Don't know where my last comment went ...

    This shows that it will not be a simple change of shower and that wiring and/or CU changes will also be required. You will now be in a better position to discuss this with your landlord and electrician.
     
  19. JP.

    JP. Screwfix Select

    Hmmmmm interesting

    You measure pd and it reads 240v

    However Uo is always 230v, and is always used in calcs - aye nominal voltage
    This is not to be confused with u

    I rest my case
     

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