Earth on main power cable Nap 250
Posted by: tube1960 on 01 November 2018
Hi all,
I have a nac 62 and nap 250 cb and have both there main power cables with the earth connected.
My question is if it is better or not to have the earth diconnected on the main power cable of my nap 250 and have it connected only on the preamp.
The digital source has the earth also disconnected on the main power cable.
Thank you for any suggestions.
Tube
The earth in any mains power cable is there for safety and should NEVER be disconnected
Any possibility of mild ground loops?
Nope
Never disconnect the mains earth on Naim equipment. It is there for safety; without the mains earth connection, if the worst ever happened and the transformer or mains wiring shorted to the chassis then the entire case could be live.
If a device has a safety earth it’s needed for safe operation.. so it mustn’t be removed. Some devices are designed differently using a double insulation technique and these will have no safety earth and typically use figure of eight connectors rather than earthed IEC connectors.
As far as earth loops or more precisely mains induction loops, well these can occur all the time and are normally harmless.. it’s when the earth induction loop compromises of a signal path in some circumstances can low level mains voltages be induced and a hum or interference of varying levels heard. Most Naim sources have a special grounding switch to allow that only one path exists in the signal chain to ground to avoid earth induction loops. In the Naim world, the traditional ground source is the CDP, if there is no CDP then you should elect just one of your sources to be the ground source.. hence the switch...all the others should be set to floating. With multiple non Naim sources connected you may get Earth induction loops.. in which case you may need to contact the source manufacturer.... but as said above never try and remedy by adjusting the mains wiring from how it is designed.
With a Naim NAP the signal grounding is through to the NAC through to the one grounded source... see above. So there is no issue with mains ground loops with the NAP from it’s mains safety earth.
The 62 doesn’t have a mains lead, so do you mean its Hicap? All boxes should be earthed if their mains leads have an earth wire. Some sources are double insulated and will only have a two core mains wire, with no separate earth, which is fine. So, if it has a three core mains lead, live neutral and earth, all three cores must be connected.
The system should only have a single signal earth, which with Naim is achieved through the source. You can get ground loops when the signal earth arrangements are incorrect, but that is nothing whatsoever to do with the mains earth.
Yes, the 62 has the Hicap.
Thank you all.
Tube