John Sayers' Recording Studio Design Forum Archive

Hi,

In my home studio, I have each 20V Isolated Ground Duplex (Hospital Grade) running back to my Sub Panel with shielded BX 10/3 cables.
From there, all studio connections including ground are connected to the Main Panel with a Loomex cable.
Basically, what I'm saying is that I don't have a distinct Ground Buss Bar that connects Ground directly to the Earth Ground over the Sub and Main panels.

However, I don't hear any hums in the studio.

So my question is: Should I add a Ground Bus Bar that connects to the Earth Ground, or is what I have good enough since I don't hear any hums in the studio?

Thanks

In the North American system, the Safety Ground (EGC) and the Isolated Ground (IG) need to somehow make a connection to the power company Neutral at the building's service entrance / main breaker box.

The connection from that Neutral/EGC/IG point to the dirt/soil has nothing to do with the quality of the AC power for your audio system.
The connection to the Earth is for safety during thunderstorms or power company high voltage accidents.

Adding to what Speedskater said: You can only have ONE physical earth connection for your building, and that one is usually close to the point where the main power feed comes into the property. So don't go adding an additional earth connection elsewhere. If that earth is not good quality, then fix it, probably by enlarging the area it covers underground (more rods/conductors) or by increasing the cross section of the conductors / ground buses in the actual electrical system, if they are not sufficient. And of course, the grounding system for your outlets should be done as "star grounding", to minimize the possibilities of creating ground loops.

But all of this is really a job for an electrician, hopefully one with studio experience who understands the issues well.

- Stuart -

The problem some of these ground systems have is that the ground connection is not efficient and there can still be a potential difference between ground and the main system. Normally caused by the soil around the copper stake drying out. I'm sure sure many
systems in dry climates would be prone to this.

We experienced it a studio I was running and the solution was to drench the ground around the copper stake with a strong saline solution. i.e. a handful of salt dissolved in a gallon of water and poured over the copper stake. Worked wonders.

cheers
john

I repeat:

The connection from that Neutral/EGC/IG point to the dirt/soil has nothing to do with the quality of the AC power for your audio system.
The connection to the Earth is for safety during thunderstorms or power company high voltage accidents.

Thanks for share...

I overlooked another purpose of the connection from that Neutral/EGC/IG point to the dirt/soil.

That is to discharge static electricity (which is DC).

Make it two purposes.

To keep the AC potential of the building near that of the earth.

Not necessary, except maybe if you have electrical wiring touching or very close to the RC.

What is the 'RC' ?

What is the 'RC' ?

Good question! I was wondering that myself... Resilient Channel, maybe? But that doesn't make much sense, in this context...

- Stuart -