The Masterlink is not intended to be earthed and as your electrician correctly points out this should not be done.

As with most electronic retail consumer products sold today, they do NOT have a earth connection.

There are a few situations where you are forced to add a "clean" earth to products which would normally not be earthed and this usually occurs when long cables such as active speaker cables are connected to the equipment which pick up RF interference on cable screens where they act as an aerial. In these cases it is acceptable to earth the incoming screen to stop the problem.

Earthing and earth related issues is actually quite a complex subject and there are different rules for different situations. For example in the US the incoming power into most homes is in fact 220 volts which is split making two 110 volt equipment feeds meaning the voltage potential to earth if a fault occurs can be very different depending which part of the phase is supplying your product.

As a general guide, if an earth is not required by a product, don't add it. If you have a problem where earthing part of the circuit may resolve a problem, get advice first. If you have an "Earth Leakage Breaker" on your incoming consumer unit, then this is likely to trip in some circumstatnces where an earth has been added.

Thanks Keith for the reply, they are saying all ML cables should be earthed ( even just between two products). If this has to be a "clean" earth presumably it will require a seperate earth rod etc. which will add expense and may be impossible in some situations ie. flats etc.

Regards Simon 

Simon,

You said

they are saying all ML cables should be earthed

Who are "they" your dealer ?

If two products are connected and the only route to earth is the screen on your low voltage Masterlink cable and a fault occurs, it can potentially destroy both products as they don't have an earth of their own. I am sure your electrcian friend will be able to show you the chapter in Edition 17 of the Electrical regulations which highlights this potential hazard and the do's and dont's related to it.

Keith,

b&o technical

Regards Simon

It was a 5 room ML setup, all was well but then had various strange probs. System would go into standby, only radio available in link rooms etc. Tested ML with b&o tester- all ok then told to try earthing. It turned out to be a fault on the vision 7 motor stand which was swapped. But have since been advised that all ML networks should be earthed. I'm just concerned about the safety/legal issues.

Regards Simon

Simon,

So, your Beovision 7 motor stand had a fault, it was swapped and that resolved the problem, so why would you wish to earth the Masterlink when the fault has been resolved and given my previous statements about earthing.