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My war against dual rcd boards

Newfutile
As each (RCD) Residual Current Device must not have more than 30% leakage current on it.
It's hard to see how dual (RCD) Residual Current Device boards can be fitted at all these days.
i come across so many dual rcd boards with solar, evse and heat pumps on them, these have all been recently installed.
i wonder if BS7671 should state: Dual (RCD) Residual Current Device boards shall not be fitted, unless it can be shown (and documented) that they are suitable for the combined leakage currents expected .
otherwise developers will keep specifying them and i will have keep educating them on the many reasons a type A rcd should not be shared with other equipment!.
maybe manuafactuers instructions should also state : not suitable for a shared rcd, for certain equipment.
Parents

  • We don't suffer unwanted tripping in our house. It's a split-load board. Standing leakage for the whole installation is around 7-9 mA. We have fairly modern appliances, lots of electronic goodies ... BUT we don't yet have EV charging and solar PV.


  • in reply to gkenyon
    gkenyon said:
    we don't yet have EV charging and solar PV.

    So no heat pump RCD selection issues then Grinning

  • in reply to Philip Oakley

    Not yet ...We won't have a heat-pump for many many years, certainly over 30 years from original CU installation.

    ... and even then (or if I'm wrong on the timescales) there's no reason a second CU can't be fitted for "renewable" technologies. The existing board doesn't have enough ways for EV, PV and HP anyway !

    Don't get me wrong, I'm not saying it's a good idea to provide a dual RCD board for a brand new installation, or on refurb, but simply providing information that supports the fact there's no need to jump at removing these boards because they aren't compatible with new technology. Other options are available.

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  • in reply to Philip Oakley

    Not yet ...We won't have a heat-pump for many many years, certainly over 30 years from original CU installation.

    ... and even then (or if I'm wrong on the timescales) there's no reason a second CU can't be fitted for "renewable" technologies. The existing board doesn't have enough ways for EV, PV and HP anyway !

    Don't get me wrong, I'm not saying it's a good idea to provide a dual RCD board for a brand new installation, or on refurb, but simply providing information that supports the fact there's no need to jump at removing these boards because they aren't compatible with new technology. Other options are available.

Children
  • in reply to gkenyon

    Can we assume they are type A RCD and not Type AC RCD

    Can we assume there is also a Type 2 SPD and is fitted pre or post main switch

  • in reply to Sergio Fernandez
    Sergio Fernandez said:
    Can we assume they are type A RCD and not Type AC RCD

    In my house, they are definitely Type AC. Been there for some time.

    Sergio Fernandez said:
    Can we assume there is also a Type 2 SPD and is fitted pre or post main switch

    One is retrofitted pre main switch ... I also had SPD on the incoming copper broadband (previously broadband and phone) cable until very recently, as we'd had a couple of surge events during thunderstorms (low level cloud-cloud strikes probably capacitively coupled into the overhead telephone wires) that damaged electronic equipment in the house connected to the copper phone wiring. (SPDs were removed from "master boxes" from NTE 3  believe). However, this is no longer an issue, we have FTTP supplying broadband now.

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