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Omitting 30ma RCD Protection for single S/O in a domestic property

Former Community Member
Former Community Member
I installed a dedicated circuit for a hifi system for a customer last year. The customer requested a 6mm2 radial from a 16A MCB housed in its own independent consumer unit into a single, un-switched socket outlet. No problem, bit unusual but no worries.I wired it using a 3c 6mm2 armoured cable as I half anticipated the forthcoming...


The hifi equipment is causing the rcd to trip when started up. I haven't been over to have a look but I am assuming that the startup current for the many power supplies (he has told me there are ten!) coupled with electronic earth leakage is causing a CPC current that is sufficient to trip the RCD (perhaps only 16ma but enough). The earthing is high integrity having a 6mm2 cpc + armour and the Zs is sufficiently low enough that the 16A MCB can be used for fault protection. So, if this wasn't domestic I'd ditch the RCD (or replace with a 100ma) assuming that my assumptions to this point are correct.


The customer has now decided he doesn't want RCD anyway for 'reasons' but I'm still wary of removing it in a domestic situation, not because I believe the installation would become less-safe but just because it contravenes regulations.


Assuming there's no fault on the equipment and it is just a case of startup/inrush current and earth leakage, what approach would you take? Remove the RCD and write it up as a deviation from 7671 with a signed disclaimer/waiver from the customer? Install a 100ma RCD? Do nothing and walk away? Something else?


Parents
  • 0
    Each piece of Hi-Fi equipment could plug into its own socket-outlet, each outlet could be protected by 30 mA RCD individually (although slight deviation from BS 7671:2018 as currently SRCDs are not "recognised" by the 18th Ed for additional protection) - and the requirements for high protective conductor currents applied for the final circuit.


    The only other option (but high protective conductor currents still apply) would be to fit BS EN 60320 couplers onto the hi-fi equipment, and provide a corresponding PDU connected to a connection unit (e.g. SFCU). Since BS EN 60320 outlets are classed as "cable couplers", no RCD is required.


    The only other issue with RCDs in dwellings, though, is the "at a depth of less than 50 mm" requirement which also often invokes 30 mA RCD for cabling in walls - but of course there are ways around that too.


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  • 0
    Each piece of Hi-Fi equipment could plug into its own socket-outlet, each outlet could be protected by 30 mA RCD individually (although slight deviation from BS 7671:2018 as currently SRCDs are not "recognised" by the 18th Ed for additional protection) - and the requirements for high protective conductor currents applied for the final circuit.


    The only other option (but high protective conductor currents still apply) would be to fit BS EN 60320 couplers onto the hi-fi equipment, and provide a corresponding PDU connected to a connection unit (e.g. SFCU). Since BS EN 60320 outlets are classed as "cable couplers", no RCD is required.


    The only other issue with RCDs in dwellings, though, is the "at a depth of less than 50 mm" requirement which also often invokes 30 mA RCD for cabling in walls - but of course there are ways around that too.


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