Shower in new build house, wire thickness?

Discussion in 'Electricians' Talk' started by stevenh, May 23, 2010.

  1. stevenh

    stevenh New Member

    Hi, there's a built in electric shower in my new house, how do i find out what thickness of wire they used so i can know if i can upgrade the unit in the future? I think it's probably a 7.5KW unit they've put in but are there any regulations for new builds that they have to use a certain wire rating?

    Also, which is better, thermostatic (with combi boiler) or electric shower in terms of flow rate? Would it be a simple job to replace the electric shower in the main bathroom (so already got hot and cold feeds) with a thermostatic shower?


  2. unphased

    unphased Screwfix Select

    Hi Steven

    All wiring has to comply with 17th edition. The size of the cable would normally be matched to the rating of the appliance. Cable is sized according to the cross sectional area (csa) of one conductor. The standardised sizes of T&E in the UK are 1.0mm2, 1.5mm2, 2.5mm2, 4.0mm2, 6.0mm2, 10.0mm2 and 16.0mm2.

    Shower circuits would normally be wired in 6.0mm2 or 10.0mm2 and I would have thought preference for 10.0mm2 on new builds. (It would be highly unlikely that the wire is 16.0mm2).

    If you can see sufficient of the grey sheath the size is usually embossed on it. The rating of the shower will be on a label inside the unit.

    As for preference of shower electric versus combi, personally I prefer combi as it gives a reasonable pressure. Electric showers can be improved with the addition of a pump but the rating of the shower would need to be high (I would say 9.0kW plus) to ensure it can heat the water fast enough on a pump. Without a pump the electric shower is reliant on the cold water pressure entering the property. Higher wattage showers (above 9.0kW heat the water more efficiently but need properly designed circuits to allow higher rated units to be installed. The highest rated shower, 10.5kW is usually classedas a 50A circuit.


    Likely to be
  3. fooman

    fooman New Member

    since when have you been able to use a pump on an electric shower up ???
  4. unphased

    unphased Screwfix Select

    I assumed you could, Chris. Triton sell one that has a built-in pump so I just assumed you could. S'pose I could be wrong. I am sometimes. :)
  5. J.P.

    J.P. New Member

  6. Removed 4

    Removed 4 New Member

    JP: is that really you? If so, why have you had to re-register here?

    Lucia x
  7. seneca2

    seneca2 New Member

    I think it is the real JP Lucia as I notice he refered to unphased as UN, I think most of us here shorten it to UP?
  8. propper spark

    propper spark Member

    That’s not an electric shower. It’s a power shower, which is a totally different thing.
  9. wally2

    wally2 New Member

    pumped shower, tank fed 9.5 kw

    [Edited by: admin]
  10. stevenh

    stevenh New Member

    Thanks for the replies. The shower is a Bristan B95 but can't find it on their website but I'm guessing it's a 9.5KW shower so should need 10mm... well i'll see if anything starts melting after i start using it then...
  11. seneca2

    seneca2 New Member

    I would think the integral pump shower such as Wally mentions has an accurately matched pump/flow/element combination. I reckon a standard shower pump would probably pass too much water for the available heat source, only a guess as i've never tried putting a pump on an electric shower!
  12. propper spark

    propper spark Member

    That's a dear price for a redring, but I guess they don't sell many and so they got you by the balls.
  13. J.P.

    J.P. New Member

    Hi Lucia and Sen. Tried signing in a while back with JP. using my E-Mail address which is my Screwfix account E-Mail and it would not work (it use to) So I just used my other E-Mail address and wrote out new account details and it all works fine now. Anyway I wish you both a very pleasant afternoon.
  14. wklivesvtime

    wklivesvtime New Member

    you cant pump lectric showers you nuggets, obviously one designed with a pump in it is a different matter but have you seen the size of the ugly *

    [Edited by: admin]
  15. J.P.

    J.P. New Member

    Wouldn't say that there ugly WK. Extremely practical, and they give a good flow rate. Very happy with the one I fitted in my bathroom.
  16. wally2

    wally2 New Member

    Don't know why admin has knocked my link off, didn't think screwfix sold this type of shower
  17. scotspark

    scotspark Member

    you can fit a pump to feed an electric shower or multiple electric showers if you wish.

    pump has to be negative head i believe

    you cant fit pump ont mains water tho must be tank fed

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