Grounded or not grounded electrical outlet?

[Peter Larsen]

Hi,

I live in Denmark where we both use grounded and not grounded electrical outlets. I have recently moved to a new apartment with grounded outlets, and immediatly started to switch the electrical wires on all my all my hifi equipment to grounded (3 pin) wall plugs.

However, is grounded current nescessarely the best possible way to feed your hifi equipment? I mean most grounded outlets are not unique, they are shared with other tennants in the apartment building, so won't that create more noise in the grounded wire from refrigerators, ovens, washing machines etc. than if I only use two pin plugs without ground?

 

[eggontoast]

The logical approach is to use whatever the equipment was designed to be used with.

A lot of equipment is double insulated so won't utilise the ground pin of the plug anyway.

 

[Peter Larsen]

90% of my equpiment comes with grounded mains cable, but that is "not relevant". My question is more focused on if grounded main cables nescessarely is the best thing. Won't they bring noise from the surrounding electrical units back to my hifi equipment?

 

[busb]

Hi Peter

Here in Blighty we have 3 pin outlets. Most modern equipment is sold with moulded 3 pin plugs that connect to the mains but some equipment does not use the earth connection (Class II - double insulated with a square within square symbol). Such equipment may have a plastic earth pin that only pushes aside the shutter on the socket that allows the L & N pins to make contact. The mains lead for such equipment is often flat with 2 wires. Most amplifiers use the earth (ground) which should be connected. Your equipment's manuals will probably say something regarding how to connect to the mains - mostly from a safety point of view.

Some equipment that has an earth connection that if left unearthed will feel "live" when the case is touched. Such equipment may get earthed through an interconnect if the stuff at the other end is itself earthed.

The earth connection both screens equipment from interference & acts as a last resort safety feature for when something inside equipment fails. Mains earth wiring should not be carrying any significant current - switching noise from stuff like fridges will mostly be on the L with some on the N line that's usually near earth potential anyway.

I would certainly earth your amplifier. As for the unearthed equipment which has 2 pin sockets, you could try reversing the plugs where they symetrical as sound quality can be improved. Also earthing equipment that can be earthed should reduce interference because noise on the N & L will have a path down to earth through any mains filter capacitors that is fitted internally to the equipment.

 

[Peter Larsen]

Hi busb,

Nice answer. I will keep my equipment grounded then. Is there any way I can measure which is N and L on the 2-pin equipment? Maybe I should replace the 2-pin plugs with new ones, so I can see which is N and L, and then mark the plug, so I can connect it with N and L positioned right in my mains conditioner.

 

[eggontoast]

90% of my equpiment comes with grounded mains cable, but that is "not relevant".

Well it is relevant, earths are put on equipment for a reason.

My question is more focused on if grounded main cables nescessarely is the best thing. Won't they bring noise from the surrounding electrical units back to my hifi equipment?

See busb's post he has covered it well.