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Upgrading 40a RCBO

  • 20-12-2024 01:08PM
    #1
    ETThrow
    Registered Users, Registered Users 2 Posts: 1 ✭


    Hi all,

    I'm doing a full, staged refurbish of my house and taking on all works bar electrics myself. As with all queries electrical I'm expecting a roasting here.

    I just had some electrical works completed last week and the new shower is tripping after around 10 minutes. It's my fault as I installed a 10.5 kW shower and never told the electrician so I'd imagine he assumed it was 9 or 10 kW. Shower is fed by a continuous 10mm t+e with switch by the consumer unit, into a 40 amp RCBO.

    The thing is he's done really well by me with regards price so far and I don't want to call him back in until he's needed next. I'm also happy there's a straightforward fix here.

    So far as I can tell a 45a rcbo will likely sort this issue right away and there would be no problems with regards load with the 10mm cable, which then brings me to my issue: I cant seem to find a 1+N rcbo in 45 amps. My preference would be for a direct one to one swap and to use one of the brands he has in the board (Hager or Garo), however I can't find one.

    The best alternative I can come up with at the moment is to fit a 63a rcbo followed by a 45A breaker. My question is, is that a professional solution? Or if anyone knows of a hager or garo 45a rcbo, I'd appreciate if they could point me in the right direction.

    Thanks for the help.



Answers

  • #2
    Explosive_Cornflake
    Registered Users, Registered Users 2 Posts: 2,175 ✭✭✭Explosive_Cornflake


    rs link, although I'll say all this is over my head.



  • #3
    Lenar3556
    Registered Users, Registered Users 2 Posts: 2,011 ✭✭✭Lenar3556


    You can get 45A RCBO’s, although it usually isn’t necessary. RCBO’s are designed not to trip at 15% overload even if this is for an indefinite duration. Having said that I suppose it is towards the limit currently and your symptoms are consistent with the tripping current being exceeded.

    Do you know what is the voltage coming into your house?

    What is the shower make/model?



  • #4
    meercat
    Registered Users, Registered Users 2 Posts: 4,909 ✭✭✭meercat


    besides the fact that this is strictly for a rec to sort


    how do you know it’s a load issue and not some other reason for it tripping


    Are you sure your home is capable of taking such a high load. If your shower is using 45amps then you only have 18amps left to play with (assuming your main fuse is 63amp). For reference your immersion will use 13 amp,kettle 10amps,washing machine/dishwasher 10amps.

    You really should consult your rec.



  • #5
    drury..
    Registered Users, Registered Users 2 Posts: 2,203 ✭✭✭drury..


    Did the REC leave a supply and someone else connected later

    That's not allowed no wonder theres a f up

    Probably not even 10.5 at 230v anyhow although sounds like overload if it's tripping consistent after 10m



  • #6
    drury..
    Registered Users, Registered Users 2 Posts: 2,203 ✭✭✭drury..


    https://www.boards.ie/discussion/2058385146/upgrading-40a-rcbo

    Rcbo >Mcb isn't a solution

    In the unlikely event you were doing it that way it would be

    Rcd > Mcb



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  • #7
    John.G
    Registered Users, Registered Users 2 Posts: 3,675 ✭✭✭John.G


    If its a RCBO tripping then possibly not o/load even though 10 minutes before tripping might point to that, a 10.5kw shower will draw 45.7A @ 230V (5.04 ohms) A type B will (if the curves are correct) trip after 10 min (600 secs) at 1.3/1.7 times rated current, say at a very minimum of 50A after 10 minutes, it would require a voltage supply of ~ 252V and a lovely 12.6kw shower for 10 minutes if my calcs are correct, but it is early in the morning. Get your REC to check it out for safety reasons.

    image.png


  • #8
    PixelCrafter
    Registered Users, Registered Users 2 Posts: 415 ✭✭PixelCrafter


    The circuit is undersized, but you can't legally change an RCBO yourself and you also can't legally work on a bathroom circuit yourself. It's supposed to be done by an REC.

    Post edited by PixelCrafter on


  • #9
    whizbang
    Registered Users, Registered Users 2 Posts: 2,033 ✭✭✭whizbang


    10.5kw shower is nothing unusual, a 40A RCBO should handle that on a normal day. Maybe the gods are trying to tell you that 10mins is just pushing it. Are you sure its not the other half watching the esb bill..!

    @10.5kw your mains will normally sag a bit, so that helps. What kind of isolator do you have ..?

    After 10 mins I would start to look at overheating somewhere. Are all connections properly tight… But it could be simply the Rcbo is old and dirty (you did say renovations are ongoing) Replace Rcbo, recheck isolator switch and try again.



  • #10
    milaganenogan
    Registered Users, Registered Users 2 Posts: 21 ✭milaganenogan


    so what's about your problem now?>



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