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Two high-power appliances on a single 40A RCD

Former Community Member
Former Community Member
I have an electric shower installed on a 40A RCD, in a room adjacent to my kitchen. The shower is only used in an emergency - i.e. when our gas boiler is unable to provide hot water to our main bathroom. I would like to take a spur from this 40A connection to use for a new double oven, which is rated at 32A. Can anyone advise on a safe and legal way to do this, ensuring that only one of the two appliances can be connected at any one time?
  • Former Community Member
    0 Former Community Member

    cfcman:

    I have an electric shower installed on a 40A RCD, in a room adjacent to my kitchen. The shower is only used in an emergency - i.e. when our gas boiler is unable to provide hot water to our main bathroom. I would like to take a spur from this 40A connection to use for a new double oven, which is rated at 32A. Can anyone advise on a safe and legal way to do this, ensuring that only one of the two appliances can be connected at any one time?




    hi cfcman out of interest, have you posted this query in any other forums or is this your first port of call? Any pictures you could provide might be really helpful in helping you with your query :)

  • 0
    This thread could have been an opportunity for learning but descended into derogatory and defensive attitudes. Engineers could have given reasoned argument, with relevant knowledge, regs and experience, to help enlighten electricians and others, but belittlement was given instead. As a moderator once cautioned, if a post isn't liked, just ignore it - and yes, I know I could ignore the thread, the point is however that hopefully, reasoned knowledge can be disseminated without the condemnation.


    And electrical work is not a profession - thereby making us professionals. We are a trade, that may try to carry out work in a professional way but that does not make us professionals in the sense of Dr's, lawyers, architects, engineers, etc, so no grandisement of the trade please.


    F
  • Former Community Member
    0 Former Community Member
    The simple issue was an existing circuit. A shower circuit. It had already been installed, presumably fit for purpose. The Ib was assessed when it was installed diversity applied, that formed the type/rating of OCPD and the cable. So In>=Ib.


    What diversity can you apply to a shower?


    Regards


     BOD
  • 0

    perspicacious:
    The simple issue was an existing circuit. A shower circuit. It had already been installed, presumably fit for purpose. The Ib was assessed when it was installed diversity applied, that formed the type/rating of OCPD and the cable. So In>=Ib.


    What diversity can you apply to a shower?


    Regards


     BOD




     

    In reply to the question from the professional engineer, I will say none.


    Andy Betteridge
  • Former Community Member
    0 Former Community Member

    weirdbeard:




    cfcman:

    I have an electric shower installed on a 40A RCD, in a room adjacent to my kitchen. The shower is only used in an emergency - i.e. when our gas boiler is unable to provide hot water to our main bathroom. I would like to take a spur from this 40A connection to use for a new double oven, which is rated at 32A. Can anyone advise on a safe and legal way to do this, ensuring that only one of the two appliances can be connected at any one time?




    hi cfcman out of interest, have you posted this query in any other forums or is this your first port of call? Any pictures you could provide might be really helpful in helping you with your query :)


     




    Hi

    This is my first (and only) port of call. Got a little more feedback than I was banking on ?

    I'm not sure what sort of pictures you had in mind, but here's one of the switch for the shower circuit (the shower being in the adjoining room). The switch spends its days in the "off" position. None of the appliances in the picture live on the circuit controlled by this switch.
    477004fe30dd506dfbdf042d4c24310a-huge-20191129_wall-switch_annotated.jpg

  • 0
    Assuming a decent job was made installing the shower circuit the fabric of the building will have to be dismantled or flooring and the floor lifted anyway, unless it is accessible in a loft or runs up surface fixed, so hat sufficient cable can be accessed to install a junction box to divert the cable.

    Then the additional equipment installed and alterations carried out, before making good again.


    That is probably half the work of installing a completely new circuit and getting on for the same materials cost.


    The cost of the cable to run back to the consumer unit, a RCBO and the other bits and pieces is not significant and I really cannot imagine the labour cost would be in the region of £800 for pulling a cable through a house, for that amount of money you can certainly take time and care doing it.


    Andy Betteridge
  • 0

    perspicacious:
    The simple issue was an existing circuit. A shower circuit. It had already been installed, presumably fit for purpose. The Ib was assessed when it was installed diversity applied, that formed the type/rating of OCPD and the cable. So In>=Ib.


    What diversity can you apply to a shower?


    Regards


     BOD




     

    But that is kind of the point, is it not?  ?
  • 0
    If it were mine I maybe inclined to use a 4 pole contactor with 2 n/o and 2 n/c contacts and a switch to power the coil, like https://www.expertelectrical.co.uk/chint-nc1-contactors
  • 0

    Farmboy:

    And electrical work is not a profession - thereby making us professionals. We are a trade, that may try to carry out work in a professional way but that does not make us professionals in the sense of Dr's, lawyers, architects, engineers, etc, so no grandisement of the trade please.




    That's an interesting viewpoint and one which I admire. One might, however, argue that design work is engineering and, therefore, professional. 20 years ago, a chum of mine (whose house was one of the first on a small estate) asked various building tradesmen whether they considered that they were professional or not. IIRC, they associated professionalism with experience and expertise. That is probably the modern interpretation.


    Another interpretation would be that a professional puts the client's interests first, but that a tradesman will sell whatever he (or she) can.

  • Former Community Member
    0 Former Community Member

    But that is kind of the point, is it not?  


    Is that a deflection or a cloud (sic)?


    Again, what diversity can you apply to a shower?


    Regards


    BOD


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