Which electric shower can I use?

Discussion in 'Electricians' Talk' started by Paul mason, Sep 15, 2018.

  1. Paul mason

    Paul mason New Member

    I have included a picture of the cable going to my electric shower. It is connected to a 40amp mcb. The cable runs approx 3m from box to shower. Am I correct this is a 6mm cable and what would be the highest kw shower I could fit on this cable ?

    Attached Files:

  2. KIAB

    KIAB Well-Known Member


    Only 3mtrs, I would have replace length with 10mm,which would give you a wider choice of showers like 9Kw on a 40A mcb.
    But, with such a short distance 6mm is rated at 47A, so you could use a 9kw but it depends whether cable is on surface or if it's plastered over then to go with 10mm, as rating for 6mm cable will drop.
    Last edited: Sep 15, 2018
  3. mhar

    mhar Member

    If it is clipped direct (not covered) then the mcb sizing is correct. If it is buried in a wall or in conduit (which is what usually happens) then the current handling capacity reduces to sub 40A so your mcb likely needs derating.

    Getting an electrician to change this cable for a 10mm cable which will handle pretty much any off the shelf shower sounds as though it would be relatively straightfoward.

    The current carrying capacity of a 6mm cable in a wall (reference method B) is 38A. If your shower does not draw more than 38A you are ok as the load is fixed and the cable cannot overheat. If not you need to employ an electrician
    KIAB likes this.
  4. seneca

    seneca Screwfix Select

    8.5 kW.

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