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Acceptable Level Ground/Earth Noise

Hi Everyone
I have a dedicated earth for my audio system.  I was digging a bore for water and lost the rod so decided to dedicate that bore for Earth.  It is about 100 feet deep an is in water.  The line runs straight to my dedicated audio room and is shared among the various audio components.  
I am running a Clearaudio DC preformence through an Avid Phallus phone stage hooked up to a ML No.  38s pre.  The cartridge is a clear audio virtuoso MM.  The ML volume level goes to 92 and the hum appears at 60. Previously when the earth was shared the hum was almost unbearable at 60 but now is significantly reduced. 
My question is that is the hum just part of the analogue experience or should it be absolutely quite? 
srafi

Showing 3 responses by erik_squires

erik_squires
16,592 posts
 
Srafi, you should follow local laws. If they are not enforced, you still should bond any ground to your service ground. Otherwise you defeat the purpose.

As for humming, start a new topic, but depends on your equipment, and if you have DC on the line.

DC can be caused by dimmer switches.

Here, the usual source of hum and ground loops is external TV like Cable or an antenna, and PC's. In both cases the best solution is a ground loop isolator.

Best,

Erik
erik_squires
16,592 posts
 
@cleeds is absolutely right. You cannot just arbitrarily make a new ground. It's in violation of local and national codes, dangerous and wont' really get you much.

It must be appropriately bonded to the house ground, which must be bonded to the neutral at the service entrance.

From that point however you may run as many grounds as you'd like.
erik_squires
16,592 posts
 
@srafi

Your utility pole does not provide a ground, it provides a neutral. It’s up to the service entrance to provide a suitable ground. You MUST bond ALL grounds together, and bond that to the neutral coming off the pole.

Having said that, you may use as many ground rods as you’d like. :) What you cannot do is arbitrarily use one rod for one room and another for the rest.

The reason for this is that is prevents the safety ground from working correctly. If a short develops to a case, and this independent ground rod is 10 feet from the house ground rod it can be many volts different than your neutral now. 10s to hundreds. It’s worse with dry soil.

The safety ground should guarantee that the case of your electronics is 0 volts, but if it's at some other, random point, it could be quite higher than 0. That's where you loose your life. :)
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