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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
  • Racked with guilt, faced with the shame and humiliation of being judged by my peers if a case came to court, I will be up at the crack of dawn to remove my two "BS 7288" RCD sw skt outlets. It was all going so well. In case I was unwell and my wife was needing to use the heavy Flymo on the lawn I enquired at the local B and Q store if there was such a thing as a safety device which would save your life if a cable was severed and a person inadvertently touched the live wire. "Oh yes", the sales lady said, these sw/skt RCDs are one our most popular lines, we sell thousands each year. Easy to fit she said. I bought two, one for the rear of the house, one for the rear. Dont forget to switch off your fusebox! she said. No mention of BS 7288, Regulation 531.3.4.1, departures, additional protection, fault protection, upstream, downstream, RCD in the fuseboard, (in fact new fuseboard), in fact re wirewing the ring circuit because it is less than 50mm deep.

    But to my horror, word had got around the neighbourhood where the safety devices were as common as double glazing, two special "wiring regulation" officers, PCs Jewsbury and Kenyon were tasked to call on every home in search of the "illegal" devices. A skip appeared in the street, and residents were seen with suspicious bags being emptied into the skip. B and Q put a notice up, "normal sw/skts out of stock" Safe from prosecution, life went on. The Flymos appeared on front gardens, with a note "free, please help yourself" Sales of petrol mowers soared. 


    Regards, UKPN
Reply
  • Racked with guilt, faced with the shame and humiliation of being judged by my peers if a case came to court, I will be up at the crack of dawn to remove my two "BS 7288" RCD sw skt outlets. It was all going so well. In case I was unwell and my wife was needing to use the heavy Flymo on the lawn I enquired at the local B and Q store if there was such a thing as a safety device which would save your life if a cable was severed and a person inadvertently touched the live wire. "Oh yes", the sales lady said, these sw/skt RCDs are one our most popular lines, we sell thousands each year. Easy to fit she said. I bought two, one for the rear of the house, one for the rear. Dont forget to switch off your fusebox! she said. No mention of BS 7288, Regulation 531.3.4.1, departures, additional protection, fault protection, upstream, downstream, RCD in the fuseboard, (in fact new fuseboard), in fact re wirewing the ring circuit because it is less than 50mm deep.

    But to my horror, word had got around the neighbourhood where the safety devices were as common as double glazing, two special "wiring regulation" officers, PCs Jewsbury and Kenyon were tasked to call on every home in search of the "illegal" devices. A skip appeared in the street, and residents were seen with suspicious bags being emptied into the skip. B and Q put a notice up, "normal sw/skts out of stock" Safe from prosecution, life went on. The Flymos appeared on front gardens, with a note "free, please help yourself" Sales of petrol mowers soared. 


    Regards, UKPN
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