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

Former Community Member over 5 years ago

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?

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0 Former Community Member over 5 years ago

Just an update on this one:

I have been able to assess the problem and it is not the RCD which is tripping (as the customer told me) but the MCB due to inrush current (I think someone called it earlier). Replaced with a C16 and all is sorted.

Going back to the original post of this actual discussion, omitting RCD protection from sockets that supply HiFi equipment because of some notion that it improves sound quality is not acceptable.

Obviously. That wasn't the customer's complaint though, it was that the "RCD" (actually MCB) was tripping, not that it affected the sound, although he did suggest that it might. Installation of an RCD will of course alter the characteristic of the incoming supply to the hi-fi equipment, nobody is arguing that, but the suggestion that it perceivably alters the sonic quality of a hifi system is very dubious.

Thanks all for the interesting discussion, even if it did amount to not much in the end!
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0 Former Community Member over 5 years ago

Just an update on this one:

I have been able to assess the problem and it is not the RCD which is tripping (as the customer told me) but the MCB due to inrush current (I think someone called it earlier). Replaced with a C16 and all is sorted.

Going back to the original post of this actual discussion, omitting RCD protection from sockets that supply HiFi equipment because of some notion that it improves sound quality is not acceptable.

Obviously. That wasn't the customer's complaint though, it was that the "RCD" (actually MCB) was tripping, not that it affected the sound, although he did suggest that it might. Installation of an RCD will of course alter the characteristic of the incoming supply to the hi-fi equipment, nobody is arguing that, but the suggestion that it perceivably alters the sonic quality of a hifi system is very dubious.

Thanks all for the interesting discussion, even if it did amount to not much in the end!
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Omitting 30ma RCD Protection for single S/O in a domestic property

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