HiFi mains and earths and RCDs

Posted by: Martin Payne on 29 September 2000

I have been told that if I want to install a mains spur with a separate earth I must protect the circuit with an RCD (Residual Current Device).

In these the mains current must pass through a very small toroid, which is not good. My electrician normally suggests installing a non-earthed spur and bypassing the RCD.

The latest Russ Andrews catalogue has details of a new 100Amp model (the MEM A100 HE) which uses much thicker wiring internally and should be much better suited to hifi applications. He reckons it sounds much better than a standard one.

RA do not stock it, but it should be available (to special order) from any electrical retailer.

May be a useful upgrade even if not installing a separate spur. I'd be interested to hear from anyone who tries out this device.

cheers, Martin

P.S. since the RCD is fitted before the fuse box it must be worked on LIVE, and there are NO FUSES to protect you either. PLEASE GET A QUALIFIED ELECTRICIAN TO DO ANY REPLACEMENT WORK.

Posted on: 30 September 2000 by Andrew L. Weekes

How about connecting a local earth to your existing house earth?

There are restrictions on minimum cable size that can be used (if your house has PME wiring), but it eliminates the need for the RCD, as all of your house earths will be at the same potential.

Providing the local earth is a good low impedance (plenty of spikes, keep it watered!), the noise from other equipment in the house shouldn't present much of a problem.

Andy.

P.S. Do check with your electrician to ensure this is acceptable, and in line with the wiring regulations.

Andrew L. Weekes
alweekes@audiophile.com